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288 results on '"Y. Prok"'

201. Observation of nuclear scaling in theA(e,e′)reaction atxB>1

Author

K. Mikhailov, P. Eugenio, R. J. Feuerbach, M. Taiuti, A. Weisberg, Patrick Girard, J. Shaw, Michael Wood, V. S. Serov, Laird Kramer, R. A. Schumacher, A. Coleman, G. Asryan, K. A. Griffioen, M. U. Mozer, O. P. Dzyubak, R. A. Niyazov, L. C. Dennis, B. E. Bonner, Bernhard Mecking, P. Corvisiero, K. V. Dharmawardane, H. Avakian, P. Stoler, S. O. Nelson, K. Hicks, P. Heimberg, C. I O Gordon, W. J. Briscoe, Susan Taylor, Jing Zhao, E. Pasyuk, S. A. Dytman, A.V. Stavinsky, M. Guidal, L. C. Maximon, M. Battaglieri, Volker D. Burkert, A. S. Biselli, L. Morand, T. A. Forest, M. Guillo, H. Denizli, C. S. Whisnant, M. Bektasoglu, J. Kuhn, D. J. Tedeschi, M. Bellis, K. Park, Hovanes Egiyan, G. Niculescu, Daijin Kim, Elton Smith, Shalev Gilad, Avraham Klein, G. V. O'Rielly, Roy Thompson, R. A. Miskimen, R. Bradford, K. Lukashin, J. Lachniet, J. S. McCarthy, G. Ricco, D. Rowntree, A. Empl, O. Pogorelko, I. I. Strakovsky, M. Anghinolfi, J. P. Cummings, E. DeSanctis, D. Branford, D. G. Jenkins, M. Mirazita, K. Sabourov, J. M. Laget, Philip L. Cole, S. Strauch, J. Connelly, M. Holtrop, James Mueller, R. S. Hakobyan, Moshe Gai, Misak Sargsian, Ivan Bedlinski, U. Thoma, J. J. Melone, Friedrich Klein, P. D. Rubin, M. Kossov, V. Sapunenko, W. K. Brooks, Valeria Muccifora, L. M. Qin, Mark Strikman, A. V. Skabelin, P. Dragovitsch, G. S. Mutchler, R. S. Hicks, Brian Raue, G. Riccardi, Latifa Elouadrhiri, Rakhsha Nasseripour, Gerard Gilfoyle, S. McAleer, Y. G. Sharabian, S. Niccolai, J. Hu, M. Klusman, L. Guo, R. DeVita, M. Ungaro, J. Hardie, R. C. Minehart, C. A. Meyer, J. W C McNabb, N. Benmouna, M. Ripani, Dinko Pocanic, Cynthia Marie Hadjidakis, Michael Dugger, B. Carnahan, H. Funsten, J. W. Price, B. B. Niczyporuk, Daniel S. Carman, Thierry Auger, S. E. Kuhn, Alexei V. Klimenko, J. H. Kelley, N. Pivnyuk, K. Sh Egiyan, C. Tur, J. Napolitano, Barry Ritchie, G. Audit, C. E. Hyde-Wright, Baile Zhang, G. Gavalian, J. Yun, D. Cords, M. M. Ito, S. A. Morrow, C. Djalali, L. Todor, A. Yegneswaran, J. R. Calarco, L. C. Smith, R. A. Demirchyan, C. Marchand, F. W. Hersman, Y. Kuang, P. Ambrozewicz, S. Stepanyan, Sylvain Bouchigny, M. Nozar, P. Rossi, D. I. Sober, E. Polli, V. Gyurjyan, R. Fatemi, S. A. Philips, A. V. Vlassov, K. Y. Kim, H. Bagdasaryan, Min Suk Kim, J. J. Manak, H. R. Weller, M. Osipenko, F. Sabatié, K. Beard, Kalvir S. Dhuga, W. Kim, F. Ronchetti, J. Ficenec, L. Ciciani, S. Simionatto, K. L. Giovanetti, B. Asavapibhop, Larry Weinstein, D. Doughty, D. Heddle, E. Anciant, A. K. Opper, M. Khandaker, Y. Ilieva, Nicola Bianchi, Hall Crannell, G. S. Adams, D. Protopopescu, K. Joo, G. E. Dodge, S. Pozdniakov, Z. L. Zhou, P. V. Degtyarenko, K. Kim, D. P. Weygand, Ji Li, I. Niculescu, D. Lawrence, M. D. Mestayer, G. A. Peterson, S. Barrow, S. Boiarinov, B. M. Preedom, J. P. Santoro, E. Wolin, J. P. Ball, Y. Prok, M. Eckhause, D. G. Crabb, M. Spraker, K. Wang, N. Dashyan, C. Salgado, C. Cetina, Michael Vineyard, L. Y. Murphy, S. Mehrabyan, and C. Butuceanu

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Helium-4, Helium-3, Nuclear Theory, Hadron, Carbon-12, Elementary particle, Atomic physics, Nuclear Experiment, Nucleon, Isotopes of helium
Abstract

The ratios of inclusive electron scattering cross sections of ${}^{4}\mathrm{He},$ ${}^{12}\mathrm{C},$ and ${}^{56}\mathrm{Fe}$ to ${}^{3}\mathrm{He}$ have been measured for the first time. It is shown that these ratios are independent of ${x}_{B}$ at ${Q}^{2}g1.4{\mathrm{GeV}}^{2}$ for ${x}_{B}g1.5,$ where the inclusive cross section depends primarily on the high momentum components of the nuclear wave function. The observed scaling shows that the momentum distributions at high-momenta have the same shape for all nuclei and differ only by a scale factor. The observed onset of the scaling at ${Q}^{2}g1.4{\mathrm{GeV}}^{2}$ and ${x}_{B}g1.5$ is consistent with the kinematical expectation that two-nucleon short range correlations (SRC) dominate the nuclear wave function at ${p}_{m}\ensuremath{\gtrsim}300\mathrm{MeV}/c.$ The values of these ratios in the scaling region can be related to the relative probabilities of SRC in nuclei with $Ag~3.$ Our data, combined with calculations and other measurements of the ${}^{3}\mathrm{H}\mathrm{e}/\mathrm{d}\mathrm{e}\mathrm{u}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{u}\mathrm{m}$ ratio, demonstrate that for nuclei with $Ag~12$ these probabilities are 4.9--5.9 times larger than in deuterium, while for ${}^{4}\mathrm{He}$ it is larger by a factor of about 3.8.

Published
2003

202. Measurement ofep→e′pπ+π−and Baryon Resonance Analysis

Author

R. Fatemi, A. Cazes, M. U. Mozer, Bernhard Mecking, K. V. Dharmawardane, A. V. Vlassov, J. Hu, M. Battaglieri, R. Bradford, R. De Vita, E. Wolin, J. J. Manak, R. A. Niyazov, B. Carnahan, Jing Zhao, S. A. Philips, E. De Sanctis, Thierry Auger, D. I. Sober, Patrick Girard, J. Shaw, Michael Wood, P. Corvisiero, E. Golovach, J. P. Ball, Y. Prok, V. S. Serov, R. A. Schumacher, Daniel S. Carman, D. Protopopescu, S. Pozdniakov, M. Garçon, M. Eckhause, G. Ricco, G. Audit, Z. L. Zhou, A. Shafi, C. E. Hyde-Wright, Philip L. Cole, M. Taiuti, M. Ripani, Moshe Gai, Friedrich Klein, M. Bektasoglu, R. S. Hicks, Brian Raue, L. Morand, T. A. Forest, Roy Thompson, Avraham Klein, G. E. Dodge, S. A. Morrow, D. G. Crabb, I. I. Strakovsky, C. Djalali, P. V. Degtyarenko, K. Kim, G. S. Adams, B. M. Preedom, M. Spraker, M. Bellis, K. Park, B. L. Berman, I. Niculescu, K. Joo, D. Lawrence, J. P. Santoro, M. Klusman, E. Anciant, M. Guidal, G. Niculescu, W. K. Brooks, L. M. Qin, A. Empl, O. Pogorelko, K. Lukashin, B. E. Bonner, M. Holtrop, U. Thoma, H. Avakian, D. P. Weygand, Dinko Pocanic, Gerald Feldman, A. K. Opper, S. E. Kuhn, W. J. Briscoe, E. Pasyuk, K. Wang, F. W. Hersman, S. A. Dytman, R. A. Miskimen, J. H. Kelley, C. Salgado, M. Khandaker, M. Nozar, B. B. Niczyporuk, N. Pivnyuk, P. Stoler, D. Branford, J. Napolitano, Elton Smith, Ji Li, Cynthia Marie Hadjidakis, M. Mirazita, J. M. Laget, G. V. O'Rielly, Michael Dugger, S. O. Nelson, M. D. Mestayer, L. Elouadrhiri, K. Hicks, M. Anghinolfi, Laird Kramer, J. P. Cummings, James Mueller, S. Boiarinov, K. S. Egiyan, G. Riccardi, J. W C McNabb, V. Sapunenko, P. D. Rubin, F. Ronchetti, Y. G. Sharabian, Valeria Muccifora, K. Mikhailov, D. G. Jenkins, M. Kossov, K. Sabourov, Rakhsha Nasseripour, J. Ficenec, M. Guillo, Gerard Gilfoyle, L. Ciciani, Hall Crannell, W. Kim, Baile Zhang, R. C. Minehart, J. R. Calarco, C. A. Meyer, S. Simionatto, C. Cetina, Michael Vineyard, P. Dragovitsch, Volker D. Burkert, A. S. Biselli, G. V. Fedotov, Y. Kuang, L. Y. Murphy, E. Polli, K. Y. Kim, A. Longhi, S. Niccolai, S. McAleer, C. Marchand, K. L. Giovanetti, B. Asavapibhop, H. Funsten, S. Stepanyan, Sylvain Bouchigny, J. W. Price, P. Rossi, L.C. Dennis, M. M. Ito, L. Todor, J. Hardie, H. Denizli, Larry Weinstein, L. C. Smith, S. J. Gaff, B. S. Ishkhanov, B. P. Quinn, D. Doughty, H. R. Weller, Alexei V. Klimenko, Barry Ritchie, D. Heddle, M. Osipenko, F. Sabatié, K. Beard, A. V. Skabelin, G. Gavalian, V. Mokeev, G. S. Mutchler, K. A. Griffioen, P. Heimberg, J. D. Kellie, Shalev Gilad, R. J. Feuerbach, A.V. Stavinsky, D. J. Tedeschi, J. S. McCarthy, J. Lachniet, D. Rowntree, Jens H. Kuhn, L. Guo, M. Ungaro, Nicola Bianchi, A. Coleman, Susan Taylor, H. Egiyan, C. S. Whisnant, K. Livingston, G. A. Peterson, S. Barrow, J. Yun, D. Cords, A. Yegneswaran, V. Gyurjyan, and H. Bagdasaryan

Subjects
Baryon, Nuclear physics, Physics, Particle physics, Meson production, Resonance analysis, General Physics and Astronomy, Resonance (particle physics)
Abstract

The cross section for the reaction ep→e'ppi(+)pi(-) was measured in the resonance region for 1.4 lt W lt 2.1 GeV and 0.5 lt Q(2) lt 1.5 GeV2/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N* and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P-13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

Published
2003

203. Kinematically complete measurement of the proton structure functionF2in the resonance region and evaluation of its moments

Author

W. Kim, Ji Li, E. Wolin, Baile Zhang, A. K. Opper, M. D. Mestayer, R. Fatemi, P. Bosted, J. P. Ball, Y. Prok, A. V. Vlassov, M. Eckhause, M. Sargsyan, Y. Kuang, J. P. Cummings, R. De Vita, E. De Sanctis, S. Boiarinov, D. I. Sober, D. G. Crabb, E. Polli, S. A. Philips, J. W C McNabb, J. Lachniet, D. Rowntree, M. Kossov, Rakhsha Nasseripour, K. Paschke, S. Mehrabyan, B. M. Preedom, M. M. Ito, H. Denizli, Elton Smith, K. S. Egiyan, J. J. Manak, G. Riccardi, B. Carnahan, M. Osipenko, J. R. Ficenec, J. R. Calarco, Shalev Gilad, Roy Thompson, F. Sabatié, M. Anghinolfi, Marco Ripani, K. Beard, M. Battaglieri, R. A. Schumacher, J. P. Santoro, James Mueller, Susan Taylor, A. Coleman, P. D. Rubin, Daniel S. Carman, H. R. Weller, K. Mikhailov, Y. G. Sharabian, E. Anciant, Thierry Auger, G. Gavalian, G. Audit, R. Bradford, C. E. Hyde-Wright, K. Lukashin, H. Egiyan, V. Sapunenko, K. Wang, K. A. Griffioen, L. C. Dennis, L. C. Smith, C. I O Gordon, S. J. Gaff, Dinko Pocanic, B. S. Ishkhanov, M. Taiuti, Alexei V. Klimenko, B. B. Niczyporuk, S. E. Kuhn, C. Salgado, L. Morand, T. A. Forest, M. Khandaker, C. S. Whisnant, J. D. Kellie, L. Y. Murphy, J. H. Kelley, C. Tur, Philip L. Cole, Avraham Klein, G. V. O'Rielly, Silvano Simula, M. Bektasoglu, H. Avakian, N. Pivnyuk, A. Cazes, J. Napolitano, L. M. Qin, Bernhard Mecking, S. Stepanyan, G. E. Dodge, K. V. Dharmawardane, Barry Ritchie, R. J. Feuerbach, Moshe Gai, P. V. Degtyarenko, K. Kim, Cynthia Marie Hadjidakis, Sylvain Bouchigny, M. Klusman, D. G. Jenkins, K. Sabourov, P. Rossi, P. Stoler, Friedrich Klein, R. S. Hicks, Brian Raue, Michael Dugger, H. O. Funsten, A. V. Skabelin, I. Niculescu, Michael Vineyard, S. A. Morrow, S. McAleer, F. Ronchetti, C. Djalali, D. Lawrence, G. S. Mutchler, S. O. Nelson, M. Guidal, G. Niculescu, Daijin Kim, L. Ciciani, Giovanni Ricco, S. Simionatto, K. Hicks, J. Hu, Hall Crannell, J. W. Price, W. J. Briscoe, C. Marchand, K. L. Giovanetti, B. Asavapibhop, Latifa Elouadrhiri, R. C. Minehart, C. A. Meyer, E. Pasyuk, M. Spraker, Larry Weinstein, D. Doughty, R. A. Niyazov, D. Heddle, S. A. Dytman, M. Holtrop, G. V. Fedotov, P. Corvisiero, D. P. Weygand, Patrick Girard, J. Shaw, Michael Wood, V. S. Serov, G. S. Adams, K. Joo, K. Park, U. Thoma, R. Clark, A. Empl, O. Pogorelko, K. Y. Kim, M. Guillo, F. W. Hersman, M. Nozar, E. Golovatch, L. Todor, D. Protopopescu, S. Pozdniakov, Z. L. Zhou, K. Livingston, W. K. Brooks, G. A. Peterson, S. Barrow, C. Cetina, Jens H. Kuhn, Nicola Bianchi, Victor Mokeev, V. Gyurjyan, H. Bagdasaryan, Min Suk Kim, L. Guo, M. Ungaro, Jing Zhao, J. Yun, D. Cords, A. Yegneswaran, Valeria Muccifora, Gerard Gilfoyle, R. A. Miskimen, Volker D. Burkert, A. S. Biselli, D. Branford, M. Mirazita, J. M. Laget, Laird Kramer, A.V. Stavinsky, D. J. Tedeschi, J. S. McCarthy, J. Domingo, P. Dragovitsch, S. Niccolai, and J. Hardie

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Cross section (physics), Proton, Momentum transfer, Moment (physics), Bibliography, Twist, Nucleon, Resonance (particle physics)
Abstract

We measured the inclusive electron-proton cross section in the nucleon resonance region (W From these data we extracted the structure function F2 and, by including other world data, we studied the Q2 evolution of its moments, Mn(Q2), in order to estimate higher twist contributions. The small statistical and systematic uncertainties of the CLAS data allow a precise extraction of the higher twists and will require significant improvements in theoretical predictions if a meaningful comparison with these new experimental results is to be made.

Published
2003

204. First Measurement of Transferred Polarization in the Exclusivee→p→e′K+Λ→Reaction

Author

L. Guo, M. Ungaro, R. Fatemi, D. S. Armstrong, A. V. Vlassov, R. C. Minehart, C. A. Meyer, G. V. Fedotov, C. Bennhold, A. Coleman, H. R. Weller, V. Sapunenko, Valeria Muccifora, J. Yun, D. Cords, L. Elouadrhiri, D. P. Weygand, Baile Zhang, J. J. Manak, S. A. Morrow, A. Yegneswaran, Gerard Gilfoyle, M. Eckhause, C. Djalali, J. P. Cummings, Susan Taylor, A. K. Opper, P. Dragovitsch, H. Egiyan, H. Denizli, Laird Kramer, R. A. Miskimen, M. Kossov, P. Ambrozewicz, Rakhsha Nasseripour, R. A. Schumacher, S. Niccolai, A. V. Skabelin, Y. Kuang, D. Branford, L. Ciciani, G. S. Adams, K. S. Egiyan, M. Mirazita, J. M. Laget, S. Stepanyan, Sylvain Bouchigny, L. C. Smith, J. Hardie, S. J. Gaff, S. Simionatto, Alexei V. Klimenko, C. S. Whisnant, E. Polli, K. Joo, B. S. Ishkhanov, L. Todor, D. Protopopescu, K. Mikhailov, P. Rossi, Barry Ritchie, K. L. Giovanetti, B. Asavapibhop, S. Pozdniakov, M. Garçon, A. Cazes, M. U. Mozer, M. Guidal, C. Cetina, E. DeSanctis, W. K. Brooks, B. B. Niczyporuk, A.V. Stavinsky, Jing Zhao, M. Spraker, Larry Weinstein, Michael Vineyard, C. I O Gordon, Z. L. Zhou, G. Niculescu, K. V. Dharmawardane, D. J. Tedeschi, Dinko Pocanic, S. E. Kuhn, N. Pivnyuk, J. Napolitano, M. Holtrop, U. Thoma, E. Anciant, Ji Li, J. R. Calarco, L. Morand, K. A. Griffioen, J. H. Kelley, G. V. O'Rielly, T. A. Forest, C. Tur, O. P. Dzyubak, R. A. Niyazov, K. Livingston, M. Khandaker, J. Lachniet, D. G. Jenkins, K. Sabourov, M. D. Mestayer, K. Paschke, D. Rowntree, P. Corvisiero, V. Gyurjyan, Elton Smith, Daniel S. Carman, S. Mehrabyan, S. McAleer, D. Doughty, D. Heddle, S. Boiarinov, Terry Mart, D. I. Sober, Avraham Klein, R. J. Feuerbach, J. R. Ficenec, M. M. Ito, B. M. Preedom, G. Audit, C. E. Hyde-Wright, J. W C McNabb, G. E. Dodge, M. Anghinolfi, R. S. Hakobyan, P. Stoler, James Mueller, J. P. Santoro, J. W. Price, P. D. Rubin, H. Bagdasaryan, J. Hu, E. N. Golovach, G. A. Peterson, S. O. Nelson, P. V. Degtyarenko, K. Hicks, Y. G. Sharabian, M. Bektasoglu, K. Wang, C. Salgado, M. Battaglieri, M. Guillo, S. Barrow, I. Niculescu, D. Lawrence, R. Bradford, B. A. Mecking, Hall Crannell, C. Marchand, Kwangsoo Kim, M. Ripani, G. Riccardi, Cynthia Marie Hadjidakis, Jens H. Kuhn, C. Butuceanu, Michael Dugger, Nicola Bianchi, H. O. Funsten, W. Kim, M. Bellis, K. Park, J. S. McCarthy, K. Y. Kim, A. Longhi, R. Clark, L. Y. Murphy, A. Empl, O. Pogorelko, K. Lukashin, G. Ricco, Philip L. Cole, M. Osipenko, E. Wolin, F. Sabatié, Moshe Gai, F. W. Hersman, Friedrich Klein, K. Beard, M. Nozar, R. S. Hicks, Brian Raue, Kalvir S. Dhuga, Patrick Girard, J. Shaw, Michael Wood, Steven M. Grimes, G. Gavalian, V. Mokeev, J. P. Ball, Federico Ronchetti, Roy Thompson, Y. Prok, V. S. Serov, L. C. Dennis, B. E. Bonner, H. Avakian, W. J. Briscoe, E. Pasyuk, P. Eugenio, M. Taiuti, S. A. Dytman, J. J. Melone, D. G. Crabb, Volker D. Burkert, A. S. Biselli, G. S. Mutchler, L. M. Qin, R. DeVita, Shalev Gilad, M. Klusman, B. Carnahan, P. Heimberg, J. D. Kellie, and Thierry Auger

Subjects
Physics, Quark, Particle physics, Spectrometer, Spins, Nuclear Theory, Quark model, Hyperon, General Physics and Astronomy, Creation and annihilation operators, Particle accelerator, Polarization (waves), law.invention, Nuclear physics, law, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The first measurements of the transferred polarization for the exclusive (e) over right arrow p --> e'K+(U) over right arrow reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q(2) from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the s (s) over bar quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Published
2003

205. Hyperon Photoproduction in the Nucleon Resonance Region

Author

G. E. Dodge, Jing Zhao, W. Kim, M. Bellis, K. Park, S. McAleer, P. V. Degtyarenko, K. Kim, R. Miskimen, J. Yun, R. Fatemi, R. J. Feuerbach, Bernhard Mecking, K. V. Dharmawardane, Hovanes Egiyan, A. V. Vlassov, J. Lachniet, I. Niculescu, D. Rowntree, G. Riccardi, D. Lawrence, R. DeVita, J. W C McNabb, J. W. Price, A. Empl, O. Pogorelko, K. Lukashin, A. Coleman, H. R. Weller, G. Ricco, R. S. Hakobyan, F. W. Hersman, M. Bektasoglu, A. V. Skabelin, G. S. Mutchler, J. J. Manak, Hall Crannell, K. A. Griffioen, G. Gavalian, V. Sapunenko, Valeria Muccifora, S. A. Philips, P. Heimberg, Philip L. Cole, B. E. Bonner, B. M. Preedom, S. A. Morrow, Shalev Gilad, P. Stoler, H. Avakian, K. S. Egiyan, L. C. Smith, G. V. O'Rielly, Gerard Gilfoyle, S. J. Gaff, Baile Zhang, J. J. Melone, K. Mikhailov, David Jenkins, P. Eugenio, Friedrich Klein, R. A. Schumacher, R. S. Hicks, M. Battaglieri, I. I. Strakovsky, C. Marchand, M. Taiuti, K. Sabourov, W. J. Briscoe, B. P. Quinn, S. A. Dytman, C. I O Gordon, D. I. Sober, W. K. Brooks, S. Taylor, M. Osipenko, J. P. Cummings, E. De Sanctis, C. S. Whisnant, J. P. Santoro, L. Morand, K. Y. Kim, T. A. Forest, D. Branford, R. A. Niyazov, M. Ripani, K. Beard, John T. O'Brien, R. Bradford, S. Stepanyan, M. Mirazita, J. M. Laget, L.C. Dennis, Cynthia Marie Hadjidakis, H. Bagdasaryan, P. Corvisiero, Chaden Djalali, M. Kossov, M. M. Ito, H. Denizli, Kalvir S. Dhuga, A. Weisberg, Sylvain Bouchigny, K. Wang, Avraham Klein, Volker D. Burkert, Federico Ronchetti, C. Butuceanu, Michael Dugger, Y. Kuang, A. S. Biselli, H. O. Funsten, K.H. Hicks, G. S. Adams, M. Guillo, C. Salgado, Patrick Girard, J. Shaw, Rakhsha Nasseripour, K. Joo, S. Strauch, B. B. Niczyporuk, E. Polli, V. Gyurjyan, A. D. Cords, S. O. Nelson, Dinko Pocanic, Michael Wood, U. Thoma, N. Pivnyuk, J. R. Calarco, V. S. Serov, S. E. Kuhn, J. Napolitano, S. Mehrabyan, Ji Li, J. H. Kelley, C. Tur, M. D. Mestayer, Laird Kramer, Alexei V. Klimenko, Elton Smith, B. A. Raue, J. R. Ficenec, Roy Thompson, Barry Ritchie, M. Anghinolfi, E. Wolin, S. Boiarinov, James Mueller, P. D. Rubin, Y. G. Sharabian, J. P. Ball, Y. Prok, M. Eckhause, Latifa Elouadrhiri, R. C. Minehart, C. A. Meyer, C. Cetina, Michael Vineyard, D. G. Crabb, D. P. Weygand, A. Yegneswaran, P. Dragovitsch, S. Niccolai, J. Hardie, A.V. Stavinsky, J. S. McCarthy, J. Hu, B. Carnahan, F. Sabatié, Thierry Auger, B. L. Berman, L. M. Qin, M. Klusman, D. Doughty, D. Heddle, L. Ciciani, Y. Ilieva, S. Simionatto, K. L. Giovanetti, B. Asavapibhop, M. Spraker, Larry Weinstein, Nicola Bianchi, E. Anciant, L. Todor, D. Protopopescu, S. Pozdniakov, Z. L. Zhou, A. Shafi, M. Khandaker, G. A. Peterson, S. Barrow, P. Rossi, E. Pasyuk, D. J. Tedeschi, M. Guidal, G. Niculescu, M. Holtrop, Daniel S. Carman, G. Audit, C. E. Hyde-Wright, M. Nozar, L. Guo, and M. Ungaro

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Particle physics, Hyperon, FOS: Physical sciences, Lambda, Lambda baryon, High Energy Physics - Experiment, Sigma baryon, Baryon, Nuclear physics, High Energy Physics - Experiment (hep-ex), Recoil, PHOTON ENERGIES, Nuclear Experiment (nucl-ex), Nuclear Experiment, Nucleon
Abstract

Cross-sections and recoil polarizations for the reactions gamma + p --> K^+ + Lambda and gamma + p --> K^+ + Sigma^0 have been measured with high statistics and with good angular coverage for center-of-mass energies between 1.6 and 2.3 GeV. In the K^+Lambda channel we confirm a structure near W=1.9 GeV at backward kaon angles, but our data shows a more complex s- and u- channel resonance structure than previously seen. This structure is present at forward and backward angles but not central angles, and its position and width change with angle, indicating that more than one resonance is playing a role. Rising back-angle cross sections at higher energies and large positive polarization at backward angles are consistent with sizable s- or u-channel contributions. None of the model calculations we present can consistently explain these aspects of the data., 5 pages, 3 figures, submitted to Physical Review Letters

Published
2003
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206. A polarized target for the CLAS detector

Author

Marco Ripani, P. Bosted, M. Anghinolfi, S. Bültmann, D. Kashy, R. Fatemi, D. G. Crabb, Y. Prok, R. De Vita, M. Taiuti, S. E. Kuhn, S.A. Comer, M. Battaglieri, S. Witherspoon, G. E. Dodge, D. Branford, M. L. Seely, Volker D. Burkert, and C. D. Keith

Subjects
Physics, Elastic scattering, Nuclear and High Energy Physics, Spectrometer, Proton, Scattering, Nuclear Theory, Detector, Electron, Polarization (waves), Nuclear physics, Nuclear Experiment, Instrumentation, Electron scattering
Abstract

We describe the design, construction, and performance of a polarized solid target for use in electron scattering experiments with the CEBAF Large Acceptance Spectrometer. Protons and deuterons are continuously polarized by microwave-induced spin–flip transitions at 1 K and 5 T . The target operated successfully during two cycles in 1998 and 2000, providing proton and deuteron polarizations as high as 96% and 46%, respectively. The unique features of the target which permit its use inside a 4π spectrometer are stressed. Comparison is made between the target polarization measured by the traditional method of NMR and by electron elastic scattering.

Published
2003

207. First measurement of transferred polarization in the exclusive ep--e'K+Lambda--reaction

Author

D S, Carman, K, Joo, M D, Mestayer, B A, Raue, G, Adams, P, Ambrozewicz, E, Anciant, M, Anghinolfi, D S, Armstrong, B, Asavapibhop, G, Audit, T, Auger, H, Avakian, H, Bagdasaryan, J P, Ball, S P, Barrow, M, Battaglieri, K, Beard, M, Bektasoglu, M, Bellis, C, Bennhold, N, Bianchi, A S, Biselli, S, Boiarinov, B E, Bonner, S, Bouchigny, R, Bradford, D, Branford, W J, Briscoe, W K, Brooks, V D, Burkert, C, Butuceanu, J R, Calarco, B, Carnahan, A, Cazes, C, Cetina, L, Ciciani, R, Clark, P L, Cole, A, Coleman, D, Cords, P, Corvisiero, D, Crabb, H, Crannell, J P, Cummings, E, DeSanctis, P V, Degtyarenko, H, Denizli, L, Dennis, R, DeVita, K V, Dharmawardane, K S, Dhuga, C, Djalali, G E, Dodge, D, Doughty, P, Dragovitsch, M, Dugger, S, Dytman, O P, Dzyubak, M, Eckhause, H, Egiyan, K S, Egiyan, L, Elouadrhiri, A, Empl, P, Eugenio, R, Fatemi, G, Fedotov, R J, Feuerbach, J, Ficenec, T A, Forest, H, Funsten, S J, Gaff, M, Gai, M, Garçon, G, Gavalian, S, Gilad, G P, Gilfoyle, K L, Giovanetti, P, Girard, E, Golovach, C I O, Gordon, K, Griffioen, S, Grimes, M, Guidal, M, Guillo, L, Guo, V, Gyurjyan, C, Hadjidakis, R S, Hakobyan, J, Hardie, D, Heddle, P, Heimberg, F W, Hersman, K, Hicks, R S, Hicks, M, Holtrop, J, Hu, C E, Hyde-Wright, B, Ishkhanov, M M, Ito, D, Jenkins, J H, Kelley, J D, Kellie, M, Khandaker, K Y, Kim, K, Kim, W, Kim, A, Klein, F J, Klein, A V, Klimenko, M, Klusman, M, Kossov, L H, Kramer, Y, Kuang, S E, Kuhn, J, Kuhn, J, Lachniet, J M, Laget, D, Lawrence, J, Li, K, Livingston, A, Longhi, K, Lukashin, J J, Manak, C, Marchand, T, Mart, S, McAleer, J, McCarthy, J W C, McNabb, B A, Mecking, S, Mehrabyan, J J, Melone, C A, Meyer, K, Mikhailov, R, Minehart, M, Mirazita, R, Miskimen, V, Mokeev, L, Morand, S A, Morrow, M U, Mozer, V, Muccifora, J, Mueller, L Y, Murphy, G S, Mutchler, J, Napolitano, R, Nasseripour, S O, Nelson, S, Niccolai, G, Niculescu, I, Niculescu, B B, Niczyporuk, R A, Niyazov, M, Nozar, G V, O'Rielly, A K, Opper, M, Osipenko, K, Park, K, Paschke, E, Pasyuk, G, Peterson, N, Pivnyuk, D, Pocanic, O, Pogorelko, E, Polli, S, Pozdniakov, B M, Preedom, J W, Price, Y, Prok, D, Protopopescu, L M, Qin, G, Riccardi, G, Ricco, M, Ripani, B G, Ritchie, F, Ronchetti, P, Rossi, D, Rowntree, P, Rubin, F, Sabatié, K, Sabourov, C, Salgado, J, Santoro, V, Sapunenko, R A, Schumacher, V S, Serov, Y G, Sharabian, J, Shaw, S, Simionatto, A V, Skabelin, E S, Smith, L C, Smith, D I, Sober, M, Spraker, A, Stavinsky, S, Stepanyan, P, Stoler, M, Taiuti, S, Taylor, D J, Tedeschi, U, Thoma, R, Thompson, L, Todor, C, Tur, M, Ungaro, M F, Vineyard, A V, Vlassov, K, Wang, L B, Weinstein, H, Weller, D P, Weygand, C S, Whisnant, E, Wolin, M H, Wood, A, Yegneswaran, J, Yun, B, Zhang, J, Zhao, and Z, Zhou

Abstract

The first measurements of the transferred polarization for the exclusive e--p--e(')K+Lambda--reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ssmacr; quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Published
2002

208. Publisher’s Note:ηPhotoproduction on the Proton for Photon Energies from 0.75 to 1.95 GeV [Phys. Rev. Lett.89, 222002 (2002)]

Author

V. V. Frolov, D. Doughty, R. A. Niyazov, John T. O'Brien, D. Heddle, Barry Ritchie, S. A. Morrow, P. Rubin, M. Eckhause, C. Djalali, P. Dragovitsch, K. A. Griffioen, G. E. Dodge, M. Lucas, P. Corvisiero, D. Hancock, E. S. Smith, Sylvain Bouchigny, P. Rossi, P. V. Degtyarenko, S. Niccolai, Carlos A. Salgado, L. Elouadrhiri, G. Ricco, J. Hardie, K. S. Egiyan, Baile Zhang, R. C. Minehart, C. A. Meyer, G. S. Mutchler, V. Koubarovski, K. Mikhailov, G. Gavalian, A. K. Opper, I. Niculescu, M. M. Ito, I. I. Strakovsky, A.V. Stavinsky, D. Lawrence, M. Spraker, C. Cetina, H. Egiyan, G. V. O'Rielly, E. Wolin, Michael Vineyard, J. P. Cummings, D. P. Weygand, L. Farhi, Y. Kuang, D. J. Tedeschi, C. S. Whisnant, D. G. Jenkins, K. Sabourov, G. P. Capitani, E. Polli, William Brooks, G. S. Adams, R. DeVita, J. W C McNabb, Ji Li, H. Denizli, Hall Crannell, M. U. Mozer, P. Heimberg, M. Witkowski, K. V. Dharmawardane, A. Coleman, P. L. Cole, Cynthia Marie Hadjidakis, Andreas Klein, J. R. Ficenec, S. McAleer, J. D. Kellie, P. Stoler, J. Lachniet, H. R. Weller, M. Kossov, J. R. Calarco, C. Marchand, M. D. Mestayer, J. J. Manak, D. Rowntree, M. Anghinolfi, James Mueller, Michael Dugger, J. Connelly, A. V. Skabelin, K. S. Dhuga, D. Pogorelko, H. O. Funsten, S. O. Nelson, Y. G. Sharabian, Frank Klein, L. C. Smith, Rakhsha Nasseripour, S. J. Gaff, K. Hicks, M. Sanzone-Arenhovel, R. A. Schumacher, S. Boiarinov, B. B. Niczyporuk, B. M. Preedom, S. Strauch, S. A. Philips, W. Kim, N. Pivnyuk, C. I O Gordon, K. Lukashin, J. Napolitano, Moshe Gai, Dinko Pocanic, M. Battaglieri, Shalev Gilad, M. Nozar, S. E. Kuhn, L. Morand, T. A. Forest, B. Carnahan, F. Sabatié, K. L. Giovanetti, B. Asavapibhop, J. H. Kelley, Stephen Taylor, J. P. Ball, Y. Prok, Patrick Girard, R. Bradford, B. A. Mecking, Larry Weinstein, Gerald Feldman, J. Shaw, S. Stepanyan, D. S. Carman, Jens H. Kuhn, A. Longhi, E. Anciant, K. Wang, U. Thoma, Nicola Bianchi, Thierry Auger, Michael Wood, R. S. Hicks, Brian Raue, K. Livingston, V. S. Serov, L. C. Dennis, M. Khandaker, G. Audit, M. Ripani, M. Guillo, C. E. Hyde-Wright, B. L. Berman, L. M. Qin, H. Avakian, R. J. Feuerbach, K. Beard, M. Klusman, D. G. Crabb, G. A. Peterson, W. Major, M. Bektasoglu, S. Barrow, M. Guidal, G. Niculescu, W. J. Briscoe, E. Pasyuk, Federico Ronchetti, M. Holtrop, Thomas E. Smith, S. A. Dytman, L. Todor, J. S. McCarthy, M. Bellis, D. Protopopescu, L. Y. Murphy, S. Pozdniakov, S. Mehrabyan, Z. L. Zhou, R. Clark, A. Shafi, G. Riccardi, J. P. Santoro, Roy Thompson, Jing Zhao, M. Taiuti, V. Sapunenko, Valeria Muccifora, Gerard Gilfoyle, F. W. Hersman, R. A. Miskimen, D. Branford, M. Mirazita, J. M. Laget, Laird Kramer, R. Fatemi, A. V. Vlassov, K. Park, D. I. Sober, Volker D. Burkert, A. S. Biselli, L. Guo, M. Ungaro, K. Joo, J. Yun, D. Cords, A. Yegneswaran, E. DeSanctis, V. Gyurjyan, H. Bagdasaryan, and J. W. Price

Subjects
Physics, Nuclear physics, Photon, Proton, General Physics and Astronomy
Published
2002

209. Measurement of ep--e' ppi+ pi- and baryon resonance analysis

Author

M, Ripani, V D, Burkert, V, Mokeev, M, Battaglieri, R, De Vita, E, Golovach, M, Taiuti, G, Adams, E, Anciant, M, Anghinolfi, B, Asavapibhop, G, Audit, T, Auger, H, Avakian, H, Bagdasaryan, J P, Ball, S, Barrow, K, Beard, M, Bektasoglu, M, Bellis, B L, Berman, N, Bianchi, A S, Biselli, S, Boiarinov, B E, Bonner, S, Bouchigny, R, Bradford, D, Branford, W J, Briscoe, W K, Brooks, J R, Calarco, D S, Carman, B, Carnahan, A, Cazes, C, Cetina, L, Ciciani, P L, Cole, A, Coleman, D, Cords, P, Corvisiero, D, Crabb, H, Crannell, J P, Cummings, E, De Sanctis, P V, Degtyarenko, H, Denizli, L, Dennis, K V, Dharmawardane, C, Djalali, G E, Dodge, D, Doughty, P, Dragovitsch, M, Dugger, S, Dytman, M, Eckhause, H, Egiyan, K S, Egiyan, L, Elouadrhiri, A, Empl, R, Fatemi, G, Fedotov, G, Feldman, R J, Feuerbach, J, Ficenec, T A, Forest, H, Funsten, S J, Gaff, M, Gai, M, Garçon, G, Gavalian, S, Gilad, G P, Gilfoyle, K L, Giovanetti, P, Girard, K, Griffioen, M, Guidal, M, Guillo, L, Guo, V, Gyurjyan, C, Hadjidakis, J, Hardie, D, Heddle, P, Heimberg, F W, Hersman, K, Hicks, R S, Hicks, M, Holtrop, J, Hu, C E, Hyde-Wright, B, Ishkhanov, M M, Ito, D, Jenkins, K, Joo, J H, Kelley, J D, Kellie, M, Khandaker, K Y, Kim, K, Kim, W, Kim, A, Klein, F J, Klein, A V, Klimenko, M, Klusman, M, Kossov, L H, Kramer, Y, Kuang, S E, Kuhn, J, Kuhn, J, Lachniet, J M, Laget, D, Lawrence, Ji, Li, K, Livingston, A, Longhi, K, Lukashin, J J, Manak, C, Marchand, S, McAleer, J, McCarthy, J W C, McNabb, B A, Mecking, M D, Mestayer, C A, Meyer, K, Mikhailov, R, Minehart, M, Mirazita, R, Miskimen, L, Morand, S A, Morrow, M U, Mozer, V, Muccifora, J, Mueller, L Y, Murphy, G S, Mutchler, J, Napolitano, R, Nasseripour, S O, Nelson, S, Niccolai, G, Niculescu, I, Niculescu, B B, Niczyporuk, R A, Niyazov, M, Nozar, G V, O'Rielly, A K, Opper, M, Osipenko, K, Park, E, Pasyuk, G, Peterson, S A, Philips, N, Pivnyuk, D, Pocanic, O, Pogorelko, E, Polli, S, Pozdniakov, B M, Preedom, J W, Price, Y, Prok, D, Protopopescu, L M, Qin, B, Quinn, B A, Raue, G, Riccardi, G, Ricco, B G, Ritchie, F, Ronchetti, P, Rossi, D, Rowntree, P D, Rubin, F, Sabatié, K, Sabourov, C, Salgado, J P, Santoro, V, Sapunenko, R A, Schumacher, V S, Serov, A, Shafi, Y G, Sharabian, J, Shaw, S, Simionatto, A V, Skabelin, E S, Smith, L C, Smith, D I, Sober, M, Spraker, A, Stavinsky, S, Stepanyan, P, Stoler, I I, Strakovsky, S, Taylor, D J, Tedeschi, U, Thoma, R, Thompson, L, Todor, M, Ungaro, M F, Vineyard, A V, Vlassov, K, Wang, L B, Weinstein, H, Weller, D P, Weygand, C S, Whisnant, E, Wolin, M H, Wood, A, Yegneswaran, J, Yun, B, Zhang, J, Zhao, and Z, Zhou

Abstract

The cross section for the reaction ep--e(')ppi(+)pi(-) was measured in the resonance region for 1.4W2.1 GeV and 0.5Q21.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

Published
2002

210. Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Author

R. Fatemi, K. S. Egiyan, V. Koubarovski, A. V. Vlassov, B. Carnahan, F. Sabatié, K. Mikhailov, C. Marchand, M. Taiuti, Thierry Auger, S. A. Morrow, C. Djalali, W. J. Briscoe, E. Pasyuk, M. Lucas, G. Ricco, S. A. Dytman, J. J. Manak, C. E. Hyde-Wright, A.V. Stavinsky, H. R. Weller, Patrick Girard, A. V. Skabelin, G. S. Mutchler, S. Stepanyan, Sylvain Bouchigny, J. Shaw, D. J. Tedeschi, S. McAleer, Philip L. Cole, Moshe Gai, R. A. Niyazov, Michael Wood, B. M. Preedom, V. S. Serov, E. Anciant, J. S. McCarthy, J. P. Santoro, A. K. Opper, M. Sanzone-Arenhovel, John T. O'Brien, D. I. Sober, F. W. Hersman, B. B. Niczyporuk, M. U. Mozer, M. Witkowski, Bernhard Mecking, K. V. Dharmawardane, B. L. Berman, Shalev Gilad, P. Rossi, W. Kim, M. Bellis, K. Park, M. Guillo, Friedrich Klein, P. Corvisiero, H. Egiyan, S. Mehrabyan, M. Khandaker, Gerald Feldman, N. Pivnyuk, J. P. Cummings, J. Napolitano, P. Dragovitsch, M. Ripani, R. S. Hicks, Brian Raue, A. Longhi, R. Clark, Roy Thompson, K. Wang, S. Strauch, C. Salgado, O. Pogorelko, D. Protopopescu, H. Funsten, M. Kossov, K. Lukashin, D. Doughty, D. Heddle, M. Klusman, C. S. Whisnant, S. Pozdniakov, L.C. Dennis, J. R. Calarco, M. M. Ito, L. Todor, J. W. Price, S. Niccolai, J. Hardie, R. J. Feuerbach, Rakhsha Nasseripour, P. Stoler, C. Cetina, S. O. Nelson, R. A. Miskimen, Volker D. Burkert, L. C. Smith, A. S. Biselli, K. Beard, S. J. Gaff, Michael Vineyard, K. A. Griffioen, Kalvir S. Dhuga, L. Y. Murphy, M. Battaglieri, G. Riccardi, R. DeVita, J. W C McNabb, E. Wolin, F. Ronchetti, V. Frolov, Ji Li, G. Gavalian, R. Bradford, Cynthia Marie Hadjidakis, D. Branford, J. Ficenec, J. P. Ball, Y. Prok, P. Heimberg, M. Eckhause, Z. L. Zhou, A. Shafi, G. V. O'Rielly, M. D. Mestayer, Michael Dugger, D. G. Jenkins, K. Sabourov, K. L. Giovanetti, B. Asavapibhop, D. G. Crabb, S. Boiarinov, L. Elouadrhiri, Larry Weinstein, M. Spraker, M. Mirazita, J. M. Laget, J. D. Kellie, I. I. Strakovsky, K. Livingston, Baile Zhang, W. K. Brooks, L. M. Qin, Laird Kramer, L. Farhi, Harut Avakian, V. Sapunenko, Valeria Muccifora, Y. Kuang, G. A. Peterson, E. Polli, Dinko Pocanic, S. Barrow, S. E. Kuhn, J. H. Kelley, Gerard Gilfoyle, Elton Smith, M. Anghinolfi, James Mueller, P. D. Rubin, Y. G. Sharabian, Jens H. Kuhn, Jing Zhao, Nicola Bianchi, Barry Ritchie, R. C. Minehart, C. A. Meyer, S. A. Philips, H. Denizli, K. Hicks, Daniel S. Carman, J. Connelly, G. Audit, M. Bektasoglu, M. Nozar, M. Guidal, G. Niculescu, M. Holtrop, Thomas E. Smith, Hall Crannell, G. E. Dodge, P. V. Degtyarenko, I. Niculescu, D. Lawrence, L. Morand, R. A. Schumacher, C. I O Gordon, T. A. Forest, Avraham Klein, V. Gyurjyan, H. Bagdasaryan, D. Hancock, W. Major, E. DeSanctis, G. P. Capitani, L. Guo, M. Ungaro, J. Lachniet, D. Rowntree, S. Taylor, G. S. Adams, K. Joo, J. Yun, A. Coleman, D. Cords, A. Yegneswaran, U. Thoma, and D. P. Weygand

Subjects
Physics, Particle physics, Photon, Meson, Proton, media_common.quotation_subject, Quark model, General Physics and Astronomy, Constituent quark, Resonance (particle physics), Asymmetry, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment, Beam (structure), media_common
Abstract

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Published
2002

211. Erratum: First Measurement of the Double Spin Asymmetry ine→p→→e′π+nin the Resonance Region [Phys. Rev. Lett. 88, 082001 (2002)]

Author

R. De Vita, M. Anghinolfi, V. D. Burkert, G. E. Dodge, R. Minehart, M. Taiuti, H. Weller, G. Adams, M. J. Amaryan, E. Anciant, D. S. Armstrong, B. Asavapibhop, G. Asryan, G. Audit, T. Auger, H. Avakian, H. Bagdasaryan, J. P. Ball, S. Barrow, M. Battaglieri, K. Beard, M. Bektasoglu, N. Bianchi, A. S. Biselli, S. Boiarinov, B. E. Bonner, P. Bosted, S. Bouchigny, D. Branford, W. K. Brooks, S. Bueltmann, J. R. Calarco, G. P. Capitani, D. S. Carman, B. Carnahan, A. Cazes, L. Ciciani, P. L. Cole, A. Coleman, J. Connelly, D. Cords, P. Corvisiero, D. Crabb, H. Crannell, J. P. Cummings, E. De Sanctis, P. V. Degtyarenko, R. Demirchyan, H. Denizli, L. Dennis, K. V. Dharmawardane, K. S. Dhuga, C. Djalali, D. Doughty, P. Dragovitsch, M. Dugger, S. Dytman, M. Eckhause, H. Egiyan, K. S. Egiyan, L. Elouadrhiri, A. Empl, L. Farhi, R. Fatemi, R. J. Feuerbach, J. Ficenec, T. A. Forest, V. Frolov, H. Funsten, S. J. Gaff, M. Gai, M. Garçon, G. Gavalian, S. Gilad, G. P. Gilfoyle, K. L. Giovanetti, P. Girard, E. Golovatch, K. Griffioen, M. Guidal, M. Guillo, V. Gyurjyan, C. Hadjidakis, D. Hancock, J. Hardie, D. Heddle, P. Heimberg, F. W. Hersman, K. Hicks, R. S. Hicks, M. Holtrop, J. Hu, C. E. Hyde-Wright, B. S. Ishkanov, M. M. Ito, D. Jenkins, K. Joo, J. H. Kelley, J. D. Kellie, M. Khandaker, K. Y. Kim, K. Kim, W. Kim, A. Klein, F. J. Klein, M. Klusman, M. Kossov, L. H. Kramer, Y. Kuang, J. Kuhn, S. E. Kuhn, J. Lachniet, J. M. Laget, D. Lawrence, Ji Li, K. Livingston, A. Longhi, K. Loukachine, M. Lucas, W. Major, J. J. Manak, C. Marchand, S. McAleer, J. McCarthy, J. W. C. McNabb, B. A. Mecking, M. D. Mestayer, C. A. Meyer, K. Mikhailov, M. Mirazita, R. Miskimen, V. Mokeev, V. Muccifora, J. Mueller, G. S. Mutchler, J. Napolitano, S. O. Nelson, G. Niculescu, I. Niculescu, B. B. Niczyporuk, R. A. Niyazov, A. K. Opper, G. V. O'Rielly, M. Osipenko, K. Park, E. Pasyuk, G. Peterson, S. A. Philips, N. Pivnyuk, D. Pocanic, O. Pogorelko, E. Polli, S. Pozdniakov, B. M. Preedom, J. W. Price, Y. Prok, D. Protopopescu, L. M. Qin, B. A. Raue, A. R. Reolon, G. Riccardi, G. Ricco, M. Ripani, B. G. Ritchie, S. Rock, F. Ronchetti, P. Rossi, D. Rowntree, P. D. Rubin, F. Sabatié, K. Sabourov, C. Salgado, V. Sapunenko, M. Sargsyan, R. A. Schumacher, V. S. Serov, A. Shafi, Y. G. Sharabian, J. Shaw, A. V. Skabelin, E. S. Smith, T. Smith, L. C. Smith, D. I. Sober, L. Sorrell, M. Spraker, A. Stavinsky, S. Stepanyan, P. Stoler, I. I. Strakovsky, S. Taylor, D. J. Tedeschi, R. Thompson, L. Todor, M. Ungaro, M. F. Vineyard, A. V. Vlassov, K. Wang, L. B. Weinstein, A. Weisberg, D. P. Weygand, C. S. Whisnant, E. Wolin, A. Yegneswaran, J. Yun, B. Zhang, J. Zhao, and Z. Zhou

Subjects
Physics, media_common.quotation_subject, Pi, General Physics and Astronomy, Resonance, Angular dependence, Atomic physics, Spin (physics), Asymmetry, Helicity, media_common
Published
2002

212. First Measurement of the Double Spin Asymmetry ine→p→→e′π+nin the Resonance Region

Author

Elton Smith, B. S. Ishkanov, E. Golovatch, M. Ungaro, V. Frolov, M. J. Amaryan, D. S. Armstrong, J. R. Calarco, S. A. Philips, J. Ficenec, L. Ciciani, R. A. Schumacher, Shalev Gilad, R. A. Demirchyan, L. C. Dennis, B. E. Bonner, M. Anghinolfi, James Mueller, T. A. Forest, S. Stepanyan, Avraham Klein, H. Avakian, A.V. Stavinsky, P. D. Rubin, Hall Crannell, Y. G. Sharabian, K. L. Giovanetti, B. Asavapibhop, L. Elouadrhiri, M. Osipenko, M. Klusman, G. E. Dodge, B. B. Niczyporuk, D. J. Tedeschi, K. Beard, Kalvir S. Dhuga, J. P. Cummings, Dinko Pocanic, R. C. Minehart, C. A. Meyer, M. Taiuti, N. Pivnyuk, J. Napolitano, R. J. Feuerbach, J. Lachniet, D. Rowntree, J. Yun, D. Cords, A. Yegneswaran, P. V. Degtyarenko, K. Kim, K. Loukachine, I. Niculescu, D. Lawrence, G. S. Adams, K. Joo, A. Cazes, Bernhard Mecking, M. Guidal, G. Niculescu, E. Pasyuk, C. Marchand, Larry Weinstein, S. A. Dytman, I. I. Strakovsky, G. Gavalian, J. S. McCarthy, K. V. Dharmawardane, R. De Vita, G. V. O'Rielly, G. Asryan, M. Holtrop, Thomas E. Smith, K. Park, M. Kossov, S. E. Kuhn, D. P. Weygand, E. Anciant, R. A. Niyazov, B. Carnahan, J. H. Kelley, D. G. Jenkins, M. Battaglieri, W. K. Brooks, A. K. Opper, A. Empl, O. Pogorelko, P. Dragovitsch, F. Sabatié, Daniel S. Carman, Sylvain Bouchigny, K. Sabourov, Federico Ronchetti, L. M. Qin, L. C. Smith, M. Khandaker, S. J. Gaff, G. Riccardi, J. W C McNabb, E. De Sanctis, P. Corvisiero, Victor Mokeev, C. E. Hyde-Wright, G. Audit, L. Sorrell, Thierry Auger, P. Rossi, Barry Ritchie, Baile Zhang, A. Weisberg, A. R. Reolon, D. Protopopescu, J. Hardie, M. Ripani, Michael Vineyard, Patrick Girard, J. Shaw, S. Pozdniakov, M. Garçon, D. Doughty, M. Bektasoglu, S. McAleer, V. Gyurjyan, C. Djalali, W. Kim, Cynthia Marie Hadjidakis, P. Stoler, H. Denizli, D. Heddle, M. Lucas, V. S. Serov, F. W. Hersman, W. Major, K. A. Griffioen, Y. Kuang, Michael Dugger, S. O. Nelson, Z. L. Zhou, H. Bagdasaryan, A. Shafi, H. Egiyan, K. Hicks, Roy Thompson, D. I. Sober, D. Hancock, E. Polli, J. Connelly, A. Coleman, Stephen M. Rock, K. S. Egiyan, M. Guillo, G. Ricco, Ji Li, C. S. Whisnant, A. Longhi, E. Wolin, K. Mikhailov, H. Funsten, P. Bosted, P. Heimberg, J. Hu, J. P. Ball, Y. Prok, J. W. Price, M. Eckhause, Philip L. Cole, M. D. Mestayer, K. Y. Kim, M. Sargsyan, J. D. Kellie, D. G. Crabb, M. Spraker, G. P. Capitani, Nicola Bianchi, K. Livingston, S. Taylor, S. Bueltmann, G. A. Peterson, S. Barrow, R. Fatemi, A. V. Vlassov, S. Boiarinov, B. M. Preedom, A. V. Skabelin, G. S. Mutchler, Moshe Gai, H. R. Weller, Friedrich Klein, R. S. Hicks, K. Wang, Brian Raue, C. Salgado, J. J. Manak, M. M. Ito, L. Todor, Laird Kramer, Jing Zhao, L. Farhi, V. Sapunenko, Valeria Muccifora, Volker D. Burkert, A. S. Biselli, Gerard Gilfoyle, R. A. Miskimen, D. Branford, M. Mirazita, and J. M. Laget

Subjects
Physics, Nuclear physics, media_common.quotation_subject, Cathode ray, General Physics and Astronomy, Resonance, High Energy Physics::Experiment, Nuclear Experiment, Spin (physics), Asymmetry, Helicity, media_common
Abstract

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Published
2002

213. First measurement of the double spin asymmetry in (--)e(--)p--e(prime)pi(+)n in the resonance region

Author

R, De Vita, M, Anghinolfi, V D, Burkert, G E, Dodge, R, Minehart, M, Taiuti, H, Weller, G, Adams, M J, Amaryan, E, Anciant, D S, Armstrong, B, Asavapibhop, G, Asryan, G, Audit, T, Auger, H, Avakian, H, Bagdasaryan, J P, Ball, S, Barrow, M, Battaglieri, K, Beard, M, Bektasoglu, N, Bianchi, A S, Biselli, S, Boiarinov, B E, Bonner, P, Bosted, S, Bouchigny, D, Branford, W K, Brooks, S, Bueltmann, J R, Calarco, G P, Capitani, D S, Carman, B, Carnahan, A, Cazes, L, Ciciani, P L, Cole, A, Coleman, J, Connelly, D, Cords, P, Corvisiero, D, Crabb, H, Crannell, J P, Cummings, E, De Sanctis, P V, Degtyarenko, R, Demirchyan, H, Denizli, L, Dennis, K V, Dharmawardane, K S, Dhuga, C, Djalali, D, Doughty, P, Dragovitsch, M, Dugger, S, Dytman, M, Eckhause, H, Egiyan, K S, Egiyan, L, Elouadrhiri, A, Empl, L, Farhi, R, Fatemi, R J, Feuerbach, J, Ficenec, T A, Forest, V, Frolov, H, Funsten, S J, Gaff, M, Gai, M, Garçon, G, Gavalian, S, Gilad, G P, Gilfoyle, K L, Giovanetti, P, Girard, E, Golovatch, K, Griffioen, M, Guidal, M, Guillo, V, Gyurjyan, C, Hadjidakis, D, Hancock, J, Hardie, D, Heddle, P, Heimberg, F W, Hersman, K, Hicks, R S, Hicks, M, Holtrop, J, Hu, C E, Hyde-Wright, B S, Ishkanov, M M, Ito, D, Jenkins, K, Joo, J H, Kelley, J D, Kellie, M, Khandaker, K Y, Kim, K, Kim, W, Kim, A, Klein, F J, Klein, M, Klusman, M, Kossov, L H, Kramer, Y, Kuang, S E, Kuhn, J, Lachniet, J M, Laget, D, Lawrence, Ji, Li, K, Livingston, A, Longhi, K, Loukachine, M, Lucas, W, Major, J J, Manak, C, Marchand, S, McAleer, J, McCarthy, J W C, McNabb, B A, Mecking, M D, Mestayer, C A, Meyer, K, Mikhailov, M, Mirazita, R, Miskimen, V, Mokeev, V, Muccifora, J, Mueller, G S, Mutchler, J, Napolitano, S O, Nelson, G, Niculescu, I, Niculescu, B B, Niczyporuk, R A, Niyazov, A K, Opper, G V, O'Rielly, M, Osipenko, K, Park, E, Pasyuk, G, Peterson, S A, Philips, N, Pivnyuk, D, Pocanic, O, Pogorelko, E, Polli, S, Pozdniakov, B M, Preedom, J W, Price, Y, Prok, D, Protopopescu, L M, Qin, B A, Raue, A R, Reolon, G, Riccardi, G, Ricco, M, Ripani, B G, Ritchie, S, Rock, F, Ronchetti, P, Rossi, D, Rowntree, P D, Rubin, F, Sabatié, K, Sabourov, C, Salgado, V, Sapunenko, M, Sargsyan, R A, Schumacher, V S, Serov, A, Shafi, Y G, Sharabian, J, Shaw, A V, Skabelin, E S, Smith, T, Smith, L C, Smith, D I, Sober, L, Sorrell, M, Spraker, A, Stavinsky, S, Stepanyan, P, Stoler, I I, Strakovsky, S, Taylor, D J, Tedeschi, R, Thompson, L, Todor, M, Ungaro, M F, Vineyard, A V, Vlassov, K, Wang, L B, Weinstein, A, Weisberg, D P, Weygand, C S, Whisnant, E, Wolin, A, Yegneswaran, J, Yun, B, Zhang, J, Zhao, and Z, Zhou

Abstract

The double spin asymmetry in the (--)e(--)p --e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Published
2001

214. Measurement of the Electric Form Factor of the Neutron throughd→(e→,e′n)patQ2=0.5(GeV/c)2

Author

T Petitjean, C. Yan, John C. Mitchell, M Mühlbauer, V. Tadevosyan, W. F. Vulcan, A Honegger, Pete Markowitz, M. Khandaker, S. Danagoulian, M. Hauger, H Wöhrle, G Milanovich, B. Zihlmann, Hartmuth Arenhövel, M Kaufmann, S Bültmann, R Lourie, G Kubon, A Cowley, C Bernet, H. Mkrtchyan, T Eden, H Anklin, O. Rondon, P Brindza, Y Farah, E Rollinde, T Southern, Donal Day, R. D. Carlini, R. Sawafta, K McFarlane, M. Zeier, R. Fatemi, S Malik, Daniela Rohe, Curtis Smith, J Zhao, Raphael Noel Tieulent, Rolf Ent, D. S. Brown, A Tobias, R. A. Lindgren, Glen A. Warren, S. A. Wood, W.U. Boeglin, S. Stepanyan, P. G. Roos, D. J. Mack, N. S. Chant, J. Lichtenstadt, Ingo Sick, C Harris, M. Steinacher, H. Breuer, Hongbo Zhu, K. Garrow, A. Ahmidouch, J. Jourdan, Y. Prok, D. McNulty, A. F. Lung, D. G. Crabb, P. McKee, and C. S. Armstrong

Subjects
Physics, Scattering, Momentum transfer, Electric form factor, General Physics and Astronomy, Particle accelerator, Electron, Polarization (waves), law.invention, Nuclear physics, Deuterium, law, High Energy Physics::Experiment, Neutron, Atomic physics, Nuclear Experiment
Abstract

We report the first measurement using a solid polarized target of the neutron electric form factor G(n)(E) via d-->(e-->,e(')n)p. G(n)(E) was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia ( 15ND3). The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility in quasifree kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find G(n)(E) = 0.04632+/-0.00616(stat)+/-0.00341(syst) at Q2 = 0.495 (GeV/c)(2).

Published
2001

215. Measurement of the electric form factor of the neutron through d--(e--,e(')n)p at Q2 = 0.5 (GeV/c)(2)

Author

H, Zhu, A, Ahmidouch, H, Anklin, H, Arenhövel, C, Armstrong, C, Bernet, W, Boeglin, H, Breuer, P, Brindza, D, Brown, S, Bültmann, R, Carlini, N, Chant, A, Cowley, D, Crabb, S, Danagoulian, D B, Day, T, Eden, R, Ent, Y, Farah, R, Fatemi, K, Garrow, C, Harris, M, Hauger, A, Honegger, J, Jourdan, M, Kaufmann, M, Khandaker, G, Kubon, J, Lichtenstadt, R, Lindgren, R, Lourie, A, Lung, D, Mack, S, Malik, P, Markowitz, K, McFarlane, P, McKee, D, McNulty, G, Milanovich, J, Mitchell, H, Mkrtchyan, M, Mühlbauer, T, Petitjean, Y, Prok, D, Rohe, E, Rollinde, O A, Rondon, P, Roos, R, Sawafta, I, Sick, C, Smith, T, Southern, M, Steinacher, S, Stepanyan, V, Tadevosyan, R, Tieulent, A, Tobias, W, Vulcan, G, Warren, H, Wöhrle, S, Wood, C, Yan, M, Zeier, J, Zhao, and B, Zihlmann

Abstract

We report the first measurement using a solid polarized target of the neutron electric form factor G(n)(E) via d--(e--,e(')n)p. G(n)(E) was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia ( 15ND3). The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility in quasifree kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find G(n)(E) = 0.04632+/-0.00616(stat)+/-0.00341(syst) at Q2 = 0.495 (GeV/c)(2).

Published
2001

216. Improved NMR system with non-resonant cable arrangement for target polarization measurements

Author

C. D. Keith, S. I. Penttilä, D. Crabb, G.R. Court, Y. Prok, D. B. Day, S. Bültmann, and M. A. Houlden

Subjects
Chemistry, business.industry, Liquid helium, Polarimetry, Cryogenics, Nuclear magnetic resonance spectroscopy, Polarization (waves), law.invention, Optics, law, visual_art, Electronic component, visual_art.visual_art_medium, business
Abstract

The implementation of a NMR circuit designed to improve the detection of small signals and avoid the pitfalls of using a resonant cable is discussed. This new circuit combines a modification of the standard Liverpool Q-meter, together with a circuit of passive components, maintained at liquid helium temperatures. Results from the first tests are presented.

Published
2001

217. Exclusive ρ0 meson electroproduction from hydrogen at CLAS

Author

C. Hadjidakis, M. Guidal, M. Garçon, J.-M. Laget, E.S. Smith, M. Vanderhaeghen, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, B. Asavapibhop, G. Asryan, G. Audit, T. Auger, H. Avakian, H. Bagdasaryan, J.P. Ball, S. Barrow, M. Battaglieri, K. Beard, M. Bektasoglu, M. Bellis, N. Benmouna, N. Bianchi, A.S. Biselli, S. Boiarinov, B.E. Bonner, S. Bouchigny, R. Bradford, D. Branford, W.J. Briscoe, W.K. Brooks, V.D. Burkert, C. Butuceanu, J.R. Calarco, D.S. Carman, B. Carnahan, C. Cetina, S. Chen, P.L. Cole, A. Coleman, D. Cords, P. Corvisiero, D. Crabb, H. Crannell, J.P. Cummings, E. De Sanctis, R. DeVita, P.V. Degtyarenko, L. Dennis, K.V. Dharmawardane, K.S. Dhuga, J.-P. Didelez, C. Djalali, G.E. Dodge, D. Doughty, P. Dragovitsch, M. Dugger, S. Dytman, O.P. Dzyubak, H. Egiyan, K.S. Egiyan, L. Elouadrhiri, A. Empl, P. Eugenio, L. Farhi, R. Fatemi, R.J. Feuerbach, T.A. Forest, V. Frolov, H. Funsten, S.J. Gaff, G. Gavalian, G.P. Gilfoyle, K.L. Giovanetti, P. Girard, C.I.O. Gordon, R.W. Gothe, K.A. Griffioen, M. Guillo, M. Guler, L. Guo, V. Gyurjyan, R.S. Hakobyan, J. Hardie, D. Heddle, F.W. Hersman, K. Hicks, H. Hleiqawi, M. Holtrop, E. Hourany, J. Hu, C.E. Hyde-Wright, Y. Ilieva, D. Ireland, M.M. Ito, D. Jenkins, H.-S. Jo, K. Joo, H.G. Juengst, J.H. Kelley, J. Kellie, M. Khandaker, K.Y. Kim, K. Kim, W. Kim, A. Klein, F.J. Klein, A.V. Klimenko, M. Klusman, M. Kossov, L.H. Kramer, S.E. Kuhn, J. Kuhn, J. Lachniet, J. Langheinrich, D. Lawrence, T. Lee, Ji Li, K. Livingstone, K. Lukashin, J.J. Manak, C. Marchand, S. McAleer, J.W.C. McNabb, B.A. Mecking, J.J. Melone, M.D. Mestayer, C.A. Meyer, K. Mikhailov, R. Minehart, M. Mirazita, R. Miskimen, L. Morand, S.A. Morrow, V. Muccifora, J. Mueller, G.S. Mutchler, J. Napolitano, R. Nasseripour, S.O. Nelson, S. Niccolai, G. Niculescu, I. Niculescu, B.B. Niczyporuk, R.A. Niyazov, M. Nozar, G.V. O'Rielly, M. Osipenko, K. Park, E. Pasyuk, G. Peterson, S.A. Philips, N. Pivnyuk, D. Pocanic, O. Pogorelko, E. Polli, S. Pozdniakov, B.M. Preedom, J.W. Price, Y. Prok, D. Protopopescu, L.M. Qin, B.A. Raue, G. Riccardi, G. Ricco, M. Ripani, B.G. Ritchie, F. Ronchetti, P. Rossi, G. Rosner, D. Rowntree, P.D. Rubin, F. Sabatié, K. Sabourov, C. Salgado, J.P. Santoro, V. Sapunenko, R.A. Schumacher, V.S. Serov, Y.G. Sharabian, J. Shaw, S. Simionatto, A.V. Skabelin, L.C. Smith, D.I. Sober, M. Spraker, A. Stavinsky, S. Stepanyan, B.E. Stokes, P. Stoler, S. Strauch, M. Taiuti, S. Taylor, D.J. Tedeschi, U. Thoma, R. Thompson, A. Tkabladze, L. Todor, C. Tur, M. Ungaro, M.F. Vineyard, A.V. Vlassov, K. Wang, L.B. Weinstein, H. Weller, D.P. Weygand, C.S. Whisnant, M. Williams, E. Wolin, M.H. Wood, A. Yegneswaran, J. Yun, and L. Zana

Subjects
Nuclear and High Energy Physics, Particle physics, Meson, Hadron, Elementary particle, Parton, PHOTONS, 01 natural sciences, Particle identification, High Energy Physics - Experiment, Nuclear physics, ELASTIC ELECTROPRODUCTION, Cross section (physics), LARGE Q(2), 0103 physical sciences, Nuclear Experiment, NUCLEON, 010306 general physics, VIRTUAL COMPTON-SCATTERING, HIGH-ENERGIES, Boson, Physics, 010308 nuclear & particles physics, VIRTUAL COMPTON-SCATTERING, VECTOR-MESONS, ELASTIC ELECTROPRODUCTION, DIFFRACTIVE PRODUCTION, PARTON DISTRIBUTIONS, HIGH-ENERGIES, LARGE Q(2), NUCLEON, PHOTOPRODUCTION, PHOTONS, PARTON DISTRIBUTIONS, DIFFRACTIVE PRODUCTION, PHOTOPRODUCTION, High Energy Physics::Experiment, Nucleon, VECTOR-MESONS
Abstract

The longitudinal and transverse components of the cross section for the $e p\to e^\prime p \rho^0$ reaction were measured in Hall B at Jefferson Laboratory using the CLAS detector. The data were taken with a 4.247 GeV electron beam and were analyzed in a range of $x_B$ from 0.2 to 0.6 and of $Q^2$ from 1.5 to 3.0 GeV$^2$. The data are compared to a Regge model based on effective hadronic degrees of freedom and to a calculation based on Generalized Parton Distributions. It is found that the transverse part of the cross section is well described by the former approach while the longitudinal part can be reproduced by the latter., Comment: 6 pages, 4 figures

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218. Observation of an Exotic Baryon with S = +1 in Photoproduction from the Proton

Author

L. C. Smith, S. J. Gaff, K. A. Griffioen, Elton Smith, J. R. Ficenec, R. A. Schumacher, G. Gavalian, V. Mokeev, M. Bellis, K. Park, M. Anghinolfi, B. L. Berman, L. M. Qin, James Mueller, P. D. Rubin, Y. G. Sharabian, C. I O Gordon, V. P. Kubarovsky, R. J. Feuerbach, J. Kuhn, Dinko Pocanic, S. E. Kuhn, J. H. Kelley, C. Tur, Roy Thompson, A. Empl, O. Pogorelko, K. Lukashin, M. Klusman, L. Morand, T. A. Forest, S. Stepanyan, E. De Sanctis, R. C. Minehart, C. A. Meyer, A. K. Opper, Shifeng Chen, D. I. Sober, P. Eugenio, M. Taiuti, L. C. Dennis, H. Avakian, P. Heimberg, B. M. Preedom, E. Polli, W. Kim, Daniel S. Carman, G. Audit, J. P. Santoro, P. Stoler, B. Carnahan, F. Sabatié, J. Hu, J. J. Melone, K. Wang, C. Salgado, D. P. Weygand, B. B. Niczyporuk, R. Fatemi, E. Wolin, G. E. Dodge, J. P. Cummings, H. Denizli, N. Pivnyuk, J. Napolitano, A. Longhi, Thierry Auger, A. V. Vlassov, S. O. Nelson, Ji Li, W. J. Briscoe, E. Pasyuk, M. D. Mestayer, M. Kossov, K. Hicks, J. R. Calarco, J. P. Ball, Y. Prok, S. A. Dytman, Susan Taylor, P. V. Degtyarenko, M. Sargsyan, Cynthia Marie Hadjidakis, S. Strauch, J. Connelly, A. V. Skabelin, S. Boiarinov, D. G. Crabb, Michael Dugger, Rakhsha Nasseripour, Alexei V. Klimenko, A. Weisberg, H. O. Funsten, K. S. Egiyan, R. DeVita, J. W C McNabb, M. Osipenko, C. Cetina, K. Mikhailov, Michael Vineyard, I. Niculescu, D. Lawrence, M. Guillo, Patrick Girard, C. S. Whisnant, J. Shaw, V. Gyurjyan, M. Nozar, Michael Wood, Barry Ritchie, K. Beard, M. U. Mozer, S. Mehrabyan, R. W. Major, L. Elouadrhiri, S. A. Morrow, C. Djalali, V. S. Serov, L. Farhi, J. J. Manak, P. Ambrozewicz, Sylvain Bouchigny, K. V. Dharmawardane, I. I. Strakovsky, P. Rossi, Kwangsoo Kim, G. Riccardi, G. S. Mutchler, M. Guidal, G. V. O'Rielly, G. Niculescu, O. P. Dzyubak, R. A. Niyazov, C. Butuceanu, H. Bagdasaryan, Hall Crannell, John T. O'Brien, N. Benmouna, C. Marchand, M. Ripani, D. Hancock, M. Battaglieri, P. Corvisiero, M. Holtrop, Thomas E. Smith, M. Ungaro, W. K. Brooks, R. Bradford, B. A. Mecking, D. G. Jenkins, K. Sabourov, K. Joo, J. Yun, D. Cords, A. Yegneswaran, G. S. Adams, S. McAleer, J. Langheinrich, S. A. Philips, U. Thoma, J. W. Price, M. M. Ito, Laird Kramer, E. Anciant, M. Bektasoglu, M. Khandaker, D. Doughty, F. W. Hersman, D. Heddle, Volker D. Burkert, A. S. Biselli, R. W. Gothe, K. Y. Kim, V. Frolov, L. Ciciani, S. Simionatto, K. L. Giovanetti, B. Asavapibhop, Hovanes Egiyan, M. Spraker, Larry Weinstein, R. A. Miskimen, H. G. Juengst, D. Branford, M. Mirazita, J. M. Laget, J. Lachniet, V. Sapunenko, Valeria Muccifora, Gerard Gilfoyle, D. Rowntree, R. S. Hakobyan, Federico Ronchetti, Philip L. Cole, Friedrich Klein, Brian Raue, P. Dragovitsch, Y. Ilieva, S. Niccolai, J. Hardie, Lei Guo, A.V. Stavinsky, D. J. Tedeschi, Nicola Bianchi, G. A. Peterson, S. Barrow, L. Todor, D. Protopopescu, S. Pozdniakov, M. Garçon, A. Shafi, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS, and Robert, Suzanne

Subjects
Physics, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], Proton, POSITIVE-STRANGENESS, PENTAQUARK, Nuclear Theory, General Physics and Astronomy, FOS: Physical sciences, PENTAQUARK, Pentaquark, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Exotic baryon, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], POSITIVE-STRANGENESS, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The reaction $\gamma p \to \pi^+K^-K^+n$ was studied at Jefferson Lab using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass $M=1555\pm 10$ MeV/c$^2$ was observed in the $nK^+$ invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c$^2$), and its statistical significance is 7.8 $\pm$ 1.0 ~$\sigma$. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by a chiral soliton model for the $\Theta^+$ baryon. In addition, the $pK^+$ invariant mass distribution was analyzed in the reaction $\gamma p\to K^-K^+p$ with high statistics in search of doubly-charged exotic baryon states. No resonance structures were found in this spectrum., Comment: 5 pages, 5 figures, add references

219. Observation of an Exotic S = +1 Baryon in Exclusive Photoproduction from the Deuteron

Author

R. J. Feuerbach, D. Heddle, M. Battaglieri, P. Eugenio, J. Lachniet, D. Rowntree, L. Todor, D. Protopopescu, M. Taiuti, G. Gavalian, V. Mokeev, S. Pozdniakov, M. Garçon, Latifa Elouadrhiri, R. C. Minehart, I. I. Strakovsky, R. Bradford, S. A. Morrow, R. S. Hakobyan, C. A. Meyer, G. V. O'Rielly, J. P. Cummings, R. De Vita, C. Djalali, M. Kossov, Rakhsha Nasseripour, R. W. Gothe, J. Ficenec, L. Ciciani, S. A. Philips, Hall Crannell, P. Ambrozewicz, W. Kim, L. C. Smith, V. Gyurjyan, D. G. Jenkins, W. K. Brooks, K. Livingston, D. P. Weygand, K. Y. Kim, S. Simionatto, P. Dragovitsch, Alexei V. Klimenko, H. Bagdasaryan, A. K. Opper, Shifeng Chen, K. L. Giovanetti, B. Asavapibhop, K. A. Griffioen, Michael Vineyard, S. Stepanyan, B. Carnahan, S. McAleer, Barry Ritchie, Sylvain Bouchigny, Larry Weinstein, G. A. Peterson, Bernhard Mecking, Daniel S. Carman, K. V. Dharmawardane, P. Rossi, P. Heimberg, E. Anciant, G. E. Dodge, L. Guo, M. Ungaro, H. Avakian, G. Audit, C. E. Hyde-Wright, S. Barrow, Ji Li, J. Hardie, M. Ripani, M. D. Mestayer, Y. Kuang, G. Riccardi, J. W C McNabb, Federico Ronchetti, P. V. Degtyarenko, K. Kim, M. Khandaker, J. Kuhn, Cynthia Marie Hadjidakis, J. R. Calarco, P. L. Cole, A. Coleman, H. R. Weller, E. Polli, S. Niccolai, H. Denizli, G. Ricco, Michael Dugger, K. Joo, M. Osipenko, Roy Thompson, F. Sabatié, Dinko Pocanic, M. Bektasoglu, J. W. Price, P. Stoler, A.V. Stavinsky, H. O. Funsten, S. Boiarinov, B. M. Preedom, B. B. Niczyporuk, I. Niculescu, D. Lawrence, J. Yun, D. Cords, N. Pivnyuk, A. Yegneswaran, J. Napolitano, B. L. Berman, K. Beard, L. M. Qin, Nicola Bianchi, D. J. Tedeschi, J. P. Santoro, R. Suleiman, G. S. Adams, K. Hicks, J. Hu, S. E. Kuhn, Kalvir S. Dhuga, A. V. Skabelin, R. A. Schumacher, M. Guidal, G. S. Mutchler, G. Niculescu, W. J. Briscoe, E. Pasyuk, J. J. Melone, K. Wang, K. S. Egiyan, Friedrich Klein, C. Tur, R. S. Hicks, Stephen Taylor, M. Klusman, F. W. Hersman, C. Salgado, C. S. Whisnant, M. Holtrop, S. A. Dytman, M. Nozar, C. I O Gordon, Brian Raue, K. Mikhailov, L.C. Dennis, M. Guillo, Elton Smith, U. Thoma, M. M. Ito, L. Morand, T. A. Forest, Avraham Klein, M. Anghinolfi, O. P. Dzyubak, R. A. Niyazov, James Mueller, John T. O'Brien, J. Shaw, P. D. Rubin, Y. G. Sharabian, P. Corvisiero, Michael Wood, V. S. Serov, M. Bellis, K. Park, V. P. Kubarovsky, A. Empl, O. Pogorelko, K. Lukashin, Laird Kramer, A. C S Lima, Volker D. Burkert, A. S. Biselli, J. D. Kellie, L. Y. Murphy, S. Mehrabyan, C. Butuceanu, E. Wolin, J. P. Ball, Y. Prok, D. G. Crabb, V. Sapunenko, Valeria Muccifora, Gerard Gilfoyle, Hovanes Egiyan, R. A. Miskimen, H. G. Juengst, D. Branford, M. Mirazita, E. De Sanctis, D. I. Sober, R. Fatemi, A. V. Vlassov, J. J. Manak, D. Doughty, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS, and Robert, Suzanne

Subjects
Physics, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], Meson, Hadron, Hyperon, FOS: Physical sciences, General Physics and Astronomy, Strangeness, Pentaquark, High Energy Physics - Experiment, Nuclear physics, Baryon, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), Exotic baryon, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], High Energy Physics::Experiment, Invariant mass, Nuclear Experiment (nucl-ex), Atomic physics, Nuclear Experiment
Abstract

In an exclusive measurement of the reaction $\gamma d \to K^+ K^- p n$, a narrow peak that can be attributed to an exotic baryon with strangeness $S=+1$ is seen in the $K^+n$ invariant mass spectrum. The peak is at $1.542\pm 0.005$ GeV/c$^2$ with a measured width of 0.021 GeV/c$^2$ FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is $5.2 \pm 0.6 \sigma$. The mass and width of the observed peak are consistent with recent reports of a narrow $S=+1$ baryon by other experimental groups., Comment: 5 pages, 5 figures

220. First observation of luminosity-driven extraction using channeling with a bent crystal

Author

R. A. Carrigan, Jr., D. Chen, G. Jackson, N. Mokhov, C. T. Murphy, S. I. Baker, S. A. Bogacz, D. Cline, S. Ramachandran, J. Rhoades, J. Rosenzweig, A. Aseev, V. Biryukov, A. Taratin, J. A. Ellison, A. Khanzadeev, Y. Prokofieva, V. Samsonov, G. Solodov, B. Newberger, E. Tsyganov, H.-J. Shih, W. Gabella, B. Cox, V. Golovatyuk, and A. McManus

Subjects
Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Luminosity-driven channeling extraction has been observed for the first time using a 900 GeV circulating proton beam at the superconducting Fermilab Tevatron. The extraction efficiency was found to be about 30%. A 150 kHz beam was obtained during luminosity-driven extraction with a tolerable background rate at the collider experiments. A 900 kHz beam was obtained when the background limits were doubled. This is the highest energy at which channeling has been observed.

Published
1998
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221. First Measurement of Hard Exclusive π^{-}Δ^{++} Electroproduction Beam-Spin Asymmetries off the Proton.

Author

Diehl S, Trotta N, Joo K, Achenbach P, Akbar Z, Armstrong WR, Atac H, Avakian H, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bossù F, Brinkmann KT, Briscoe WJ, Bulumulla D, Burkert V, Capobianco R, Carman DS, Carvajal JC, Celentano A, Charles G, Chatagnon P, Chesnokov V, Ciullo G, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Deur A, Djalali C, Dupre R, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Gavalian G, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Gotra Y, Griffioen K, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Illari I, Ireland DG, Isupov EL, Jo HS, Johnston R, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Klimenko V, Kripko A, Kubarovsky V, Kuhn SE, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, MacGregor IJD, Marchand D, Mascagna V, Matousek G, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Milner RG, Mineeva T, Mirazita M, Mokeev V, Moran P, Munoz Camacho C, Naidoo P, Neupane K, Niccolai S, Niculescu G, Osipenko M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Paul SJ, Phelps W, Pilleux N, Pokhrel M, Poudel J, Price JW, Prok Y, Radic A, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schadmand S, Schmidt A, Sharabian YG, Shrestha U, Sokhan D, Sparveris N, Spreafico M, Stepanyan S, Strakovsky I, Strauch S, Turisini M, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei X, Williams R, Wishart R, Wood MH, Yurov M, Zachariou N, Zhao ZW, and Zurek M

Abstract

The polarized cross-section ratio σ_{LT^{'}}/σ_{0} from hard exclusive π^{-}Δ^{++} electroproduction off an unpolarized hydrogen target has been extracted based on beam-spin asymmetry measurements using a 10.2  GeV/10.6  GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. The study, which provides the first observation of this channel in the deep-inelastic regime, focuses on very forward-pion kinematics in the valence regime, and photon virtualities ranging from 1.5  GeV^{2} up to 7  GeV^{2}. The reaction provides a novel access to the d-quark content of the nucleon and to p→Δ^{++} transition generalized parton distributions. A comparison to existing results for hard exclusive π^{+}n and π^{0}p electroproduction is provided, which shows a clear impact of the excitation mechanism, encoded in transition generalized parton distributions, on the asymmetry.

Published
2023
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222. First CLAS12 Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries in the Extended Valence Region.

Author

Christiaens G, Defurne M, Sokhan D, Achenbach P, Akbar Z, Amaryan MJ, Atac H, Avakian H, Gayoso CA, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benkel B, Benmokhtar F, Bianconi A, Biselli AS, Bondi M, Booth WA, Bossù F, Boiarinov S, Brinkmann KT, Briscoe WJ, Bueltmann S, Bulumulla D, Burkert VD, Cao T, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Chetry T, Ciullo G, Clash G, Cole PL, Contalbrigo M, Costantini G, D'Angelo A, Dashyan N, De Vita R, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, Ehrhart M, Alaoui AE, Fassi LE, Elouadrhiri L, Fegan S, Filippi A, Gates K, Gavalian G, Ghandilyan Y, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hafidi K, Hakobyan H, Hattawy M, Hauenstein F, Hayward TB, Heddle D, Hobart A, Holmberg DE, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Keller D, Khachatryan M, Khanal A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lagerquist V, Lanza L, Kabir ML, Leali M, Lee S, Lenisa P, Li X, Livingston K, MacGregor IJD, Marchand D, Mascagna V, Matousek G, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Milner RG, Mineeva T, Mirazita M, Mokeev V, Molina E, Camacho CM, Nadel-Turonski P, Naidoo P, Neupane K, Niccolai S, Nicol M, Niculescu G, Osipenko M, Ouillon M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Paul SJ, Phelps W, Pilleux N, Pokhrel M, Poudel J, Price JW, Prok Y, Radic A, Ramasubramanian N, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schadmand S, Schmidt A, Scott MBC, Sharabian YG, Shirokov EV, Shrestha U, Simmerling P, Sparveris N, Spreafico M, Stepanyan S, Strakovsky II, Strauch S, Tan JA, Trotta N, Turisini M, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei X, Williams R, Wishart R, Wood MH, Zachariou N, Zhang J, Zhao ZW, Ziegler V, and Zurek M

Abstract

Deeply virtual Compton scattering (DVCS) allows one to probe generalized parton distributions describing the 3D structure of the nucleon. We report the first measurement of the DVCS beam-spin asymmetry using the CLAS12 spectrometer with a 10.2 and 10.6 GeV electron beam scattering from unpolarized protons. The results greatly extend the Q^{2} and Bjorken-x phase space beyond the existing data in the valence region and provide 1600 new data points measured with unprecedented statistical uncertainty, setting new, tight constraints for future phenomenological studies.

Published
2023
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223. First Measurement of Λ Electroproduction off Nuclei in the Current and Target Fragmentation Regions.

Author

Chetry T, El Fassi L, Brooks WK, Dupré R, El Alaoui A, Hafidi K, Achenbach P, Adhikari KP, Akbar Z, Armstrong WR, Arratia M, Atac H, Avakian H, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benkel B, Benmokhtar F, Bianconi A, Biselli AS, Bondi M, Booth WA, Bossù F, Boiarinov S, Brinkmann KT, Briscoe WJ, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Ciullo G, Cole PL, Contalbrigo M, Costantini G, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Djalali C, Egiyan H, Elouadrhiri L, Eugenio P, Fegan S, Filippi A, Gavalian G, Ghandilyan Y, Gilfoyle GP, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Griffioen KA, Guidal M, Guo L, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jenkins D, Jo HS, Kabir ML, Khanal A, Khandaker M, Kim A, Kim W, Klein FJ, Kripko A, Kubarovsky V, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, Livingston K, MacGregor IJD, Marchand D, Mascagna V, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Mineeva T, Mirazita M, Mokeev V, Munoz Camacho C, Nadel-Turonski P, Neupane K, Niccolai S, Nicol M, Niculescu G, Osipenko M, Ostrovidov AI, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Paul SJ, Phelps W, Pilleux N, Pokhrel M, Poudel J, Price JW, Prok Y, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rosner G, Sabatié F, Salgado C, Schadmand S, Schmidt A, Schumacher RA, Sharabian YG, Shirokov EV, Shrestha U, Simmerling P, Sokhan D, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tan JA, Trotta N, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Wei X, Weinstein LB, Williams R, Wishart R, Wood MH, Yurov M, Zachariou N, Zhao ZW, and Zurek M

Abstract

We report results of Λ hyperon production in semi-inclusive deep-inelastic scattering off deuterium, carbon, iron, and lead targets obtained with the CLAS detector and the Continuous Electron Beam Accelerator Facility 5.014 GeV electron beam. These results represent the first measurements of the Λ multiplicity ratio and transverse momentum broadening as a function of the energy fraction (z) in the current and target fragmentation regions. The multiplicity ratio exhibits a strong suppression at high z and an enhancement at low z. The measured transverse momentum broadening is an order of magnitude greater than that seen for light mesons. This indicates that the propagating entity interacts very strongly with the nuclear medium, which suggests that propagation of diquark configurations in the nuclear medium takes place at least part of the time, even at high z. The trends of these results are qualitatively described by the Giessen Boltzmann-Uehling-Uhlenbeck transport model, particularly for the multiplicity ratios. These observations will potentially open a new era of studies of the structure of the nucleon as well as of strange baryons.

Published
2023
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224. Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12.

Author

Avakian H, Hayward TB, Kotzinian A, Armstrong WR, Atac H, Ayerbe Gayoso C, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benkel B, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Boiarinov S, Bossù F, Brinkman KT, Briscoe WJ, Brooks WK, Bueltmann S, Bulumulla D, Burkert VD, Capobianco R, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Chetry T, Ciullo G, Cole PL, Contalbrigo M, Costantini G, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Forest T, Gates K, Gavalian G, Ghandilyan Y, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hakobyan H, Hattawy M, Hauenstein F, Heddle D, Hobart A, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Johnston R, Joo K, Kabir ML, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Klimenko V, Kripko A, Kubarovsky V, Kuhn SE, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, MacGregor IJD, Marchand D, Mascagna V, McKinnon B, Migliorati S, Mineeva T, Mirazita M, Mokeev V, Montgomery RA, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Neupane K, Nguyen D, Niccolai S, Nicol M, Niculescu G, Osipenko M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Paul SJ, Phelps W, Pilleux N, Pogorelko O, Pokhrel M, Poudel J, Price JW, Prok Y, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schmidt A, Sharabian YG, Shirokov EV, Shrestha U, Simmerling P, Sokhan D, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tan JA, Trotta N, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei X, Wishart R, Wood MH, Zachariou N, Zhao ZW, and Zurek M

Abstract

We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back dihadron electroproduction in the deep inelastic scattering process. In this reaction, two hadrons are produced in opposite hemispheres along the z axis in the virtual photon-target nucleon center-of-mass frame, with the first hadron produced in the current-fragmentation region and the second in the target-fragmentation region. The data were taken with longitudinally polarized electron beams of 10.2 and 10.6 GeV incident on an unpolarized liquid-hydrogen target using the CLAS12 spectrometer at Jefferson Lab. Observed nonzero sinΔϕ modulations in ep→e^{'}pπ^{+}X events, where Δϕ is the difference of the azimuthal angles of the proton and pion in the virtual photon and target nucleon center-of-mass frame, indicate that correlations between the spin and transverse momenta of hadrons produced in the target- and current-fragmentation regions may be significant. The measured beam-spin asymmetries provide a first access in dihadron production to a previously unexplored leading-twist spin- and transverse-momentum-dependent fracture function. The fracture functions describe the hadronization of the target remnant after the hard scattering of a virtual photon off a quark in the target particle and provide a new avenue for studying nucleonic structure and hadronization.

Published
2023
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225. Observation of Azimuth-Dependent Suppression of Hadron Pairs in Electron Scattering off Nuclei.

Author

Paul SJ, Morán S, Arratia M, El Alaoui A, Hakobyan H, Brooks W, Amaryan MJ, Armstrong WR, Atac H, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benkel B, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Bossù F, Boiarinov S, Brinkmann KT, Briscoe WJ, Bulumulla D, Burkert VD, Capobianco R, Carman DS, Celentano A, Chesnokov V, Chetry T, Ciullo G, Cole PL, Contalbrigo M, Costantini G, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, El Fassi L, Eugenio P, Fegan S, Filippi A, Gavalian G, Ghandilyan Y, Gilfoyle GP, Golubenko AA, Gosta G, Gothe RW, Griffioen KA, Guidal M, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Johnston R, Joo K, Joosten S, Keller D, Khanal A, Khandaker M, Kim W, Kripko A, Kubarovsky V, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, Livingston K, MacGregor IJD, Marchand D, Mascagna V, McKinnon B, Meziani ZE, Migliorati S, Milner RG, Mineeva T, Mirazita M, Mokeev VI, Moran P, Munoz Camacho C, Neupane K, Nguyen D, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pilleux N, Pocanic D, Pogorelko O, Pokhrel M, Poudel J, Price JW, Prok Y, Raue BA, Reed T, Ripani M, Rosner G, Sabatié F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shirokov EV, Shrestha U, Simmerling P, Sokhan D, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tan JA, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Wei X, Wishart R, Wood MH, Zachariou N, Zhao ZW, Ziegler V, and Zurek M

Abstract

We present the first measurement of dihadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the gibuu model, which suggests that hadrons form near the nuclear surface and undergo multiple scattering in nuclei.These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei.

Published
2022
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226. Multidimensional, High Precision Measurements of Beam Single Spin Asymmetries in Semi-inclusive π^{+} Electroproduction off Protons in the Valence Region.

Author

Diehl S, Kim A, Angelini G, Joo K, Adhikari S, Amaryan M, Arratia M, Atac H, Avakian H, Ayerbe Gayoso C, Baltzell NA, Barion L, Bastami S, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bondi M, Bossù F, Boiarinov S, Brinkmann KT, Briscoe WJ, Brooks W, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clark L, Clary BA, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Dilks C, Djalali C, Dugger M, Dupre R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Forest T, Gavalian G, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hafidi K, Hakobyan H, Hattawy M, Hauenstein F, Hayward TB, Heddle D, Hicks K, Hobart A, Holtrop M, Hyde CE, Ireland DG, Isupov EL, Jo HS, Johnston R, Joosten S, Keller D, Khachatryan M, Khanal A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lee S, Lenisa P, Livingston K, Lu Z, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Meziani ZE, Milner RG, Mineeva T, Mirazita M, Mokeev V, Moran P, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Nanda S, Neupane K, Niccolai S, Niculescu G, O'Connell TR, Osipenko M, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Prok Y, Prokudin A, Raue BA, Ripani M, Ritman J, Rizzo A, Roberts CD, Rossi P, Rowley J, Sabatié F, Salgado C, Schmidt A, Segarra EP, Sharabian YG, Shrestha U, Simmerling P, Sokhan D, Soto O, Sparveris N, Stepanyan S, Stoler P, Strakovsky II, Strauch S, Tezgin K, Thornton A, Tyler N, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei K, Wei X, Xu SS, Yale B, Zachariou N, and Zhang J

Abstract

High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single π^{+} SIDIS data over a large kinematic range in Bjorken x, fractional energy, and transverse momentum of the hadron as well as photon virtualities Q^{2} ranging from 1-7  GeV^{2}. In particular, the structure function ratio F_{LU}^{sinϕ}/F_{UU} has been determined, where F_{LU}^{sinϕ} is a twist-3 quantity that can reveal novel aspects of emergent hadron mass and quark-gluon correlations within the nucleon. The data's impact on the evolving understanding of the underlying reaction mechanisms and their kinematic variation is explored using theoretical models for the different contributing transverse momentum dependent parton distribution functions.

Published
2022
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227. Improved Λp Elastic Scattering Cross Sections between 0.9 and 2.0  GeV/c as a Main Ingredient of the Neutron Star Equation of State.

Author

Rowley J, Compton N, Djalali C, Hicks K, Price J, Zachariou N, Adhikari KP, Armstrong WR, Atac H, Baashen L, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dupré R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Eugenio P, Fedotov G, Fegan S, Fersch R, Filippi A, Fradi A, Gavalian G, Girod FX, Glazier DI, Golubenko A, Gothe RW, Griffioen K, Guo L, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jenkins D, Jo HS, Joo K, Keller D, Khanal A, Khandaker M, Kim A, Korover I, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McCracken ME, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Mineeva T, Mirazita M, Mokeev V, Munevar E, Munoz Camacho C, Nadel-Turonski P, Neupane K, Niccolai S, Niculescu G, O'Connell TR, Osipenko M, Ostrovidov AI, Pandey P, Paolone M, Pappalardo LL, Pasyuk E, Pogorelko O, Prok Y, Reed T, Ripani M, Ritman J, Rizzo A, Rosner G, Sabatie F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Sokhan D, Soto O, Sparveris N, Strakovsky II, Strauch S, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei K, Wei X, Wishart R, Wood MH, Yale B, Yurov M, Zhang J, and Zhao ZW

Abstract

Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state. Yet, compared to other elastic scattering processes, there is very little data on Λ-N scattering. This experiment utilized the CEBAF Large Acceptance Spectrometer (CLAS) detector to study the Λp→Λp elastic scattering cross section in the incident Λ momentum range 0.9-2.0  GeV/c. These are the first data on this reaction since the 1970s. The new cross sections have significantly better accuracy and precision than the existing world data, and the techniques developed here can also be used in future experiments.

Published
2021
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228. First Measurement of Timelike Compton Scattering.

Author

Chatagnon P, Niccolai S, Stepanyan S, Amaryan MJ, Angelini G, Armstrong WR, Atac H, Ayerbe Gayoso C, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Caudron M, Celentano A, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, Defurne M, De Vita R, Deur A, Diehl S, Djalali C, Dupré R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Fersch R, Filippi A, Gavalian G, Ghandilyan Y, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Guo L, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Joo K, Kabir ML, Keller D, Khachatryan G, Khanal A, Kim A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lee S, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Marsicano L, Mascagna V, McKinnon B, McLauchlin C, Migliorati S, Mirazita M, Mokeev V, Montgomery RA, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Neupane K, O'Connell TR, Osipenko M, Ouillon M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Poudel J, Price JW, Prok Y, Raue BA, Reed T, Ripani M, Rizzo A, Rossi P, Rowley J, Sabatié F, Schmidt A, Segarra EP, Sharabian YG, Shirokov EV, Shrestha U, Sokhan D, Soto O, Sparveris N, Strakovsky II, Strauch S, Tyler N, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei K, Wei X, Wishart R, Yale B, Zachariou N, Zhang J, and Zhao ZW

Abstract

We present the first measurement of the timelike Compton scattering process, γp→p^{'}γ^{*}(γ^{*}→e^{+}e^{-}), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25

Published
2021
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229. Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12.

Author

Hayward TB, Dilks C, Vossen A, Avakian H, Adhikari S, Angelini G, Arratia M, Atac H, Ayerbe Gayoso C, Baltzell NA, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bondì M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clary BA, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Djalali C, Dupre R, Dugger M, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Forest TA, Gavalian G, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hafidi K, Hakobyan H, Hattawy M, Hauenstein F, Hicks K, Hobart A, Holtrop M, Ireland DG, Isupov EL, Jo HS, Joo K, Joosten S, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lee S, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Meziani ZE, Mirazita M, Mokeev V, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Nanda S, Neupane K, Niccolai S, Niculescu G, O'Connell TR, Osipenko M, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Prok Y, Raue BA, Ripani M, Ritman J, Rizzo A, Rossi P, Rowley J, Sabatié F, Salgado C, Schmidt A, Segarra EP, Sharabian YG, Shrestha U, Sokhan D, Soto O, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Thornton A, Tyler N, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei K, Wei X, Wood MH, Yale B, Zachariou N, and Zhang J

Abstract

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function G_{1}^{⊥}. A clear sign change is observed around the ρ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark.

Published
2021
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230. Photoproduction of the f_{2}(1270) Meson Using the CLAS Detector.

Author

Carver M, Celentano A, Hicks K, Marsicano L, Mathieu V, Pilloni A, Adhikari KP, Adhikari S, Amaryan MJ, Angelini G, Atac H, Baltzell NA, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bondi M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Chatagnon P, Chetry T, Ciullo G, Clark L, Clary BA, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Djalali C, Dugger M, Dupre R, Egiyan H, Ehrhart M, Alaoui AE, Fassi LE, Eugenio P, Fedotov G, Fegan S, Filippi A, Gavalian G, Gevorgyan N, Gilfoyle GP, Girod FX, Gothe RW, Griffioen KA, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Holtrop M, Huang Q, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jenkins D, Jo HS, Joo K, Joosten S, Keller D, Khanal A, Khandaker M, Kim A, Kim CW, Klein FJ, Kripko A, Kubarovsky V, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Mascagna V, McCracken ME, McKinnon B, Meziani ZE, Mokeev V, Movsisyan A, Munevar E, Camacho CM, Nadel-Turonski P, Neupane K, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Prok Y, Protopopescu D, Ripani M, Ritchie BG, Ritman J, Rizzo A, Rosner G, Rowley J, Sabatié F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Sokhan D, Soto O, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tyler N, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei K, Wei X, Yale B, Zachariou N, Zhang J, and Zhao ZW

Abstract

The quark structure of the f_{2}(1270) meson has, for many years, been assumed to be a pure quark-antiquark (qq[over ¯]) resonance with quantum numbers J^{PC}=2^{++}. Recently, it was proposed that the f_{2}(1270) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ→π^{+}π^{-}, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction γp→π^{0}π^{0}p, using the CEBAF Large Acceptance Spectrometer detector at Jefferson Lab for incident beam energies between 3.6 and 5.4 GeV. Differential cross sections, dσ/dt, for f_{2}(1270) photoproduction are extracted with good precision due to low backgrounds and are compared to theoretical calculations.

Published
2021
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231. Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs.

Author

Mirazita M, Avakian H, Courtoy A, Pisano S, Adhikari S, Amaryan MJ, Angelini G, Atac H, Baltzell NA, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clary B, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, Ehrhart M, Alaoui AE, Fassi LE, Eugenio P, Fegan S, Fersch R, Filippi A, Forest TA, Ghandilyan Y, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Glazier DI, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guo L, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hicks K, Hobart A, Holtrop M, Huang Q, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Joo K, Keller D, Khanal A, Khandaker M, Kim CW, Kim W, Klein FJ, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Milner RG, Mineeva T, Mokeev V, Mullen C, Camacho CM, Neupane K, Niculescu G, O'Connell T, Osipenko M, Paolone M, Pappalardo LL, Paremuzyan R, Park K, Pasyuk E, Phelps W, Pocanic D, Pogorelko O, Poudel J, Prok Y, Raue BA, Ripani M, Ritman J, Rizzo A, Rossi P, Sabatié F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Soto O, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tyler N, Ungaro M, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts D, Wei K, Wei X, Wood MH, Yale B, Zachariou N, Zhang J, and Zhao ZW

Abstract

A first measurement of the longitudinal beam spin asymmetry A_{LU} in the semi-inclusive electroproduction of pairs of charged pions is reported. A_{LU} is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the A_{LU}^{sinϕ_{R}} moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production is essential for the interpretation of observables in single-hadron production in semi-inclusive DIS, and pioneering measurements of single-spin asymmetries in dihadron production open a new avenue in studies of QCD dynamics.

Published
2021
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232. Extraction of Beam-Spin Asymmetries from the Hard Exclusive π^{+} Channel off Protons in a Wide Range of Kinematics.

Author

Diehl S, Joo K, Kim A, Avakian H, Kroll P, Park K, Riser D, Semenov-Tian-Shansky K, Tezgin K, Adhikari KP, Adhikari S, Amaryan MJ, Angelini G, Asryan G, Atac H, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Dilks C, Djalali C, Dupre R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Eugenio P, Filippi A, Forest TA, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Girod FX, Glazier DI, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guo L, Hakobyan H, Harrison N, Hattawy M, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Joosten S, Keller D, Khachatryan M, Khanal A, Khandaker M, Kim CW, Kim W, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Meziani ZE, Mineeva T, Mirazita M, Mokeev V, Munoz Camacho C, Nadel-Turonski P, Niculescu G, Osipenko M, Paolone M, Pappalardo LL, Pasyuk E, Phelps W, Pogorelko O, Price JW, Prok Y, Raue BA, Ripani M, Rizzo A, Rossi P, Rowley J, Sabatié F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Soto O, Sparveris N, Stepanyan S, Stoler P, Strakovsky II, Strauch S, Tan JA, Tyler N, Ungaro M, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei X, Wood MH, Zachariou N, Zhang J, and Zhao ZW

Abstract

We have measured beam-spin asymmetries to extract the sinϕ moment A_{LU}^{sinϕ} from the hard exclusive e[over →]p→e^{'}nπ^{+} reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The A_{LU}^{sinϕ} moment has been measured up to 6.6  GeV^{2} in -t, covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found A_{LU}^{sinϕ} to be negative, while a sign change was observed near 90° in the center of mass. The unique results presented in this Letter will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.

Published
2020
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233. Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering.

Author

Hattawy M, Baltzell NA, Dupré R, Bültmann S, De Vita R, El Alaoui A, El Fassi L, Egiyan H, Girod FX, Guidal M, Hafidi K, Jenkins D, Liuti S, Perrin Y, Stepanyan S, Torayev B, Voutier E, Adhikari S, Angelini G, Ayerbe Gayoso C, Barion L, Battaglieri M, Bedlinskiy I, Biselli AS, Bossù F, Brooks W, Cao F, Carman DS, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Sanctis E, Defurne M, Deur A, Diehl S, Djalali C, Ehrhart M, Eugenio P, Fegan S, Filippi A, Forest TA, Fradi A, Garçon M, Gavalian G, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Golovatch E, Gothe RW, Griffioen KA, Harrison N, Hauenstein F, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Johnston S, Keller D, Khachatryan G, Khachatryan M, Khanal A, Khandaker M, Kim CW, Kim W, Klein FJ, Kubarovsky V, Kuhn SE, Lanza L, L Kabir M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Mayer M, McKinnon B, Meziani ZE, Mineeva T, Mirazita M, Montgomery RA, Munoz Camacho C, Nadel-Turonski P, Niccolai S, Ostrovidov AI, Pappalardo LL, Paremuzyan R, Pasyuk E, Pogorelko O, Poudel J, Prok Y, Protopopescu D, Ripani M, Riser D, Rizzo A, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Sharabian YG, Skorodumina I, Sokhan D, Soto O, Sparveris N, Strauch S, Taiuti M, Tan JA, Tyler N, Ungaro M, Voskanyan H, Wang R, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zhang J, and Zhao ZW

Abstract

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this Letter, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering off a proton bound in ^{4}He. The data used here were accumulated using a 6 GeV longitudinally polarized electron beam incident on a pressurized ^{4}He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle (ϕ) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The Q^{2}, x_{B}, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20% to 40%, indicating possible medium modification of its partonic structure.

Published
2019
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234. Direct Observation of Proton-Neutron Short-Range Correlation Dominance in Heavy Nuclei.

Author

Duer M, Schmidt A, Pybus JR, Segarra EP, Hrnjic A, Denniston AW, Weiss R, Hen O, Piasetzky E, Weinstein LB, Barnea N, Korover I, Cohen EO, Hakobyan H, Adhikari S, Angelini G, Battaglieri M, Beck A, Bedlinskiy I, Biselli AS, Boiarinov S, Brooks W, Burkert VD, Cao F, Carman DS, Celentano A, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Cortes O, Crede V, Cruz Torres R, D'Angelo A, Dashyan N, De Sanctis E, De Vita R, Deur A, Diehl S, Djalali C, Dupre R, Duran B, Egiyan H, El Alaoui A, El Fassi L, Eugenio P, Filippi A, Forest TA, Gilfoyle GP, Giovanetti KL, Girod FX, Golovatch E, Gothe RW, Griffioen KA, Guo L, Hafidi K, Hanretty C, Harrison N, Hattawy M, Hauenstein F, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Joo K, Kabir ML, Keller D, Khachatryan M, Khanal A, Khandaker M, Kim W, Klein FJ, Kubarovsky V, Kuhn SE, Lanza L, Laskaris G, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, McKinnon B, Mey-Tal Beck S, Mirazita M, Mokeev V, Montgomery RA, Movsisyan A, Munoz Camacho C, Mustapha B, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Paremuzyan R, Park K, Pasyuk E, Patsyuk M, Phelps W, Pogorelko O, Prok Y, Protopopescu D, Ripani M, Rizzo A, Rosner G, Rossi P, Sabatié F, Schmookler BA, Schumacher RA, Sharabian Y, Skorodumina I, Sokhan D, Sparveris N, Stepanyan S, Strauch S, Taiuti M, Tan JA, Tyler N, Ungaro M, Voskanyan H, Voutier E, Wang R, Wei X, Wood MH, Zachariou N, Zhang J, Zhao ZW, and Zheng X

Abstract

We measured the triple coincidence A(e,e^{'}np) and A(e,e^{'}pp) reactions on carbon, aluminum, iron, and lead targets at Q^{2}>1.5  (GeV/c)^{2}, x_{B}>1.1 and missing momentum >400  MeV/c. This was the first direct measurement of both proton-proton (pp) and neutron-proton (np) short-range correlated (SRC) pair knockout from heavy asymmetric nuclei. For all measured nuclei, the average proton-proton (pp) to neutron-proton (np) reduced cross-section ratio is about 6%, in agreement with previous indirect measurements. Correcting for single-charge exchange effects decreased the SRC pairs ratio to ∼3%, which is lower than previous results. Comparisons to theoretical generalized contact formalism (GCF) cross-section calculations show good agreement using both phenomenological and chiral nucleon-nucleon potentials, favoring a lower pp to np pair ratio. The ability of the GCF calculation to describe the experimental data using either phenomenological or chiral potentials suggests possible reduction of scale and scheme dependence in cross-section ratios. Our results also support the high-resolution description of high-momentum states being predominantly due to nucleons in SRC pairs.

Published
2019
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235. First Measurements of the Double-Polarization Observables F, P, and H in ω Photoproduction off Transversely Polarized Protons in the N^{*} Resonance Region.

Author

Roy P, Park S, Crede V, Anisovich AV, Klempt E, Nikonov VA, Sarantsev AV, Wei NC, Huang F, Nakayama K, Adhikari KP, Adhikari S, Angelini G, Avakian H, Barion L, Battaglieri M, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe WJ, Brock J, Brooks WK, Burkert VD, Cao F, Carlin C, Carman DS, Celentano A, Chatagnon P, Chetry T, Ciullo G, Cole PL, Contalbrigo M, Cortes O, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Diehl S, Djalali C, Dugger M, Dupre R, Duran B, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Eugenio P, Fegan S, Filippi A, Fradi A, Gilfoyle GP, Girod FX, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guo L, Hafidi K, Hanretty C, Harrison N, Hattawy M, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Johnston S, Joosten S, Kabir ML, Keith CD, Keller D, Khachatryan G, Khachatryan M, Khanal A, Khandaker M, Kim A, Kim W, Klein FJ, Kubarovsky V, Kuleshov SV, Kunkel MC, Lanza L, Lenisa P, Livingston K, MacGregor IJD, Marchand D, McKinnon B, Meekins DG, Meyer CA, Mineeva T, Mokeev V, Montgomery RA, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Payette D, Phelps W, Pierce J, Pogorelko O, Prok Y, Protopopescu D, Raue BA, Ripani M, Riser D, Ritchie BG, Rizzo A, Rosner G, Sabatié F, Salgado C, Schumacher RA, Seely ML, Sharabian YG, Shrestha U, Skorodumina I, Sokhan D, Soto O, Sparveris N, Strakovsky II, Strauch S, Taiuti M, Tan JA, Torayev B, Tyler N, Ungaro M, Voskanyan H, Voutier E, Walford NK, Wang R, Watts DP, Wei X, Wood MH, Zachariou N, Zhang J, and Zhao ZW

Abstract

First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.

Published
2019
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236. Center of Mass Motion of Short-Range Correlated Nucleon Pairs studied via the A(e,e^{'}pp) Reaction.

Author

Cohen EO, Hen O, Piasetzky E, Weinstein LB, Duer M, Schmidt A, Korover I, Hakobyan H, Adhikari S, Akbar Z, Amaryan MJ, Avakian H, Ball J, Barion L, Battaglieri M, Beck A, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe W, Burkert VD, Cao F, Carman DS, Celentano A, Charles G, Chatagnon P, Chetry T, Ciullo G, Clary BA, Contalbrigo M, Crede V, Cruz Torres R, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Defurne M, Deur A, Diehl S, Djalali C, Duer M, Dupre R, Egiyan H, Ehrhart M, El Alaoui A, Fassi LE, Eugenio P, Fedotov G, Fersch R, Filippi A, Ghandilyan Y, Giovanetti KL, Girod FX, Golovatch E, Gothe RW, Griffioen KA, Hafidi K, Harrison N, Hauenstein F, Heddle D, Hicks K, Holtrop M, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Johnston S, Kabir ML, Keller D, Khachatryan G, Khachatryan M, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Korover I, Kubarovsky V, Kuhn SE, Lanza L, Lenisa P, Livingston K, MacGregor IJD, Marchand D, McKinnon B, Mey-Tal Beck S, Meyer CA, Mirazita M, Mokeev V, Montgomery RA, Movsisyan A, Munoz Camacho C, Mustapha B, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Paremuzyan R, Pasyuk E, Pogorelko O, Price JW, Prok Y, Protopopescu D, Ripani M, Riser D, Rizzo A, Rosner G, Rossi P, Sabatié F, Schmookler BA, Schumacher RA, Sharabian YG, Sokhan D, Sparveris N, Stepanyan S, Strauch S, Taiuti M, Tan JA, Ungaro M, Voskanyan H, Voutier E, Wang R, Watts DP, Wei X, Wood MH, Zachariou N, Zhang J, Zheng X, and Zhao ZW

Abstract

Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_{F}). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_{F}, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e^{'}pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170  MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states.

Published
2018
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237. Measurement of the Q^{2} Dependence of the Deuteron Spin Structure Function g_{1} and its Moments at Low Q^{2} with CLAS.

Author

Adhikari KP, Deur A, El Fassi L, Kang H, Kuhn SE, Ripani M, Slifer K, Zheng X, Adhikari S, Akbar Z, Amaryan MJ, Avakian H, Ball J, Balossino I, Barion L, Battaglieri M, Bedlinskiy I, Biselli AS, Bosted P, Briscoe WJ, Brock J, Bültmann S, Burkert VD, Thanh Cao F, Carlin C, Carman DS, Celentano A, Charles G, Chen JP, Chetry T, Choi S, Ciullo G, Clark L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Defurne M, Djalali C, Dodge GE, Drozdov V, Dupre R, Egiyan H, El Alaoui A, Elouadrhiri L, Eugenio P, Fedotov G, Filippi A, Ghandilyan Y, Gilfoyle GP, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Hafidi K, Hakobyan H, Hanretty C, Harrison N, Hattawy M, Heddle D, Hicks K, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jenkins D, Jo HS, Johnston SC, Joo K, Joosten S, Kabir ML, Keith CD, Keller D, Khachatryan G, Khachatryan M, Khandaker M, Kim W, Klein A, Klein FJ, Konczykowski P, Kovacs K, Kubarovsky V, Lanza L, Lenisa P, Livingston K, Long E, MacGregor IJD, Markov N, Mayer M, McKinnon B, Meekins DG, Meyer CA, Mineeva T, Mirazita M, Mokeev V, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Niculescu G, Niccolai S, Osipenko M, Ostrovidov AI, Paolone M, Pappalardo L, Paremuzyan R, Park K, Pasyuk E, Payette D, Phelps W, Phillips SK, Pierce J, Pogorelko O, Poudel J, Price JW, Prok Y, Protopopescu D, Raue BA, Rizzo A, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Sharabian YG, Shigeyuki T, Simonyan A, Skorodumina I, Smith GD, Sparveris N, Sokhan D, Stepanyan S, Strakovsky II, Strauch S, Sulkosky V, Taiuti M, Tan JA, Ungaro M, Voutier E, Wei X, Weinstein LB, Zhang J, and Zhao ZW

Abstract

We measured the g_{1} spin structure function of the deuteron at low Q^{2}, where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W≈1.9  GeV. The generalized Gerasimov-Drell-Hearn sum, the moment Γ_{1}^{d} and the spin polarizability γ_{0}^{d} are precisely determined down to a minimum Q^{2} of 0.02  GeV^{2} for the first time, about 2.5 times lower than that of previous data. We compare them to several χPT calculations and models. These results are the first in a program of benchmark measurements of polarization observables in the χPT domain.

Published
2018
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238. First Exclusive Measurement of Deeply Virtual Compton Scattering off ^{4}He: Toward the 3D Tomography of Nuclei.

Author

Hattawy M, Baltzell NA, Dupré R, Hafidi K, Stepanyan S, Bültmann S, De Vita R, El Alaoui A, El Fassi L, Egiyan H, Girod FX, Guidal M, Jenkins D, Liuti S, Perrin Y, Torayev B, Voutier E, Adhikari KP, Adhikari S, Adikaram D, Akbar Z, Amaryan MJ, Anefalos Pereira S, Armstrong WR, Avakian H, Ball J, Bashkanov M, Battaglieri M, Batourine V, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe WJ, Brooks WK, Burkert VD, Thanh Cao F, Carman DS, Celentano A, Charles G, Chetry T, Ciullo G, Clark L, Colaneri L, Cole PL, Contalbrigo M, Cortes O, Crede V, D'Angelo A, Dashyan N, De Sanctis E, Deur A, Djalali C, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Fersch R, Filippi A, Fleming JA, Forest TA, Fradi A, Garçon M, Gevorgyan N, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Gleason C, Gohn W, Golovatch E, Gothe RW, Griffioen KA, Guo L, Hakobyan H, Hanretty C, Harrison N, Heddle D, Hicks K, Holtrop M, Hughes SM, Ireland DG, Ishkhanov BS, Isupov EL, Jiang H, Joo K, Joosten S, Keller D, Khachatryan G, Khachatryan M, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Kubarovsky V, Kuhn SE, Kuleshov SV, Lanza L, Lenisa P, Livingston K, Lu HY, MacGregor IJD, Markov N, Mayer M, McCracken ME, McKinnon B, Meyer CA, Meziani ZE, Mineeva T, Mirazita M, Mokeev V, Montgomery RA, Moutarde H, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Net LA, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Paolone M, Paremuzyan R, Park K, Pasyuk E, Phelps E, Phelps W, Pisano S, Pogorelko O, Price JW, Prok Y, Protopopescu D, Ripani M, Ritchie BG, Rizzo A, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Seder E, Sharabian YG, Simonyan A, Skorodumina I, Smith GD, Sokhan D, Sparveris N, Strauch S, Taiuti M, Ungaro M, Voskanyan H, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zana L, Zhang J, and Zhao ZW

Abstract

We report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment uses the 6 GeV electron beam from the Continuous Electron Beam Accelerator Facility (CEBAF) accelerator at Jefferson Lab incident on a pressurized ^{4}He gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron is detected by CLAS and the photon by a dedicated electromagnetic calorimeter at forward angles. To ensure the exclusivity of the process, a specially designed radial time projection chamber is used to detect the recoiling ^{4}He nuclei. We measure beam-spin asymmetries larger than those observed on the free proton in the same kinematic domain. From these, we are able to extract, in a model-independent way, the real and imaginary parts of the only ^{4}He Compton form factor, H_{A}. This first measurement of coherent deeply virtual Compton scattering on the ^{4}He nucleus, with a fully exclusive final state via nuclear recoil tagging, leads the way toward 3D imaging of the partonic structure of nuclei.

Published
2017
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239. New Measurements of the Beam Normal Spin Asymmetries at Large Backward Angles with Hydrogen and Deuterium Targets.

Author

Ríos DB, Aulenbacher K, Baunack S, Diefenbach J, Gläser B, von Harrach D, Imai Y, Kabuß EM, Kothe R, Lee JH, Merkel H, Mora Espí MC, Müller U, Schilling E, Weinrich C, Capozza L, Maas FE, Arvieux J, El-Yakoubi MA, Frascaria R, Kunne R, Morlet M, Ong S, van de Wiele J, Kowalski S, and Prok Y

Abstract

New measurements of the beam normal single spin asymmetry in the electron elastic and quasielastic scattering on the proton and deuteron, respectively, at large backward angles and at ⟨Q^{2}⟩=0.22  (GeV/c)^{2} and ⟨Q^{2}⟩=0.35  ( GeV/c)^{2} are reported. The experimentally observed asymmetries are compared with the theoretical calculation of Pasquini and Vanderhaeghen [Phys. Rev. C 70, 045206 (2004).PRVCAN0556-281310.1103/PhysRevC.70.045206]. The agreement of the measurements with the theoretical calculations shows a dominance of the inelastic intermediate excited states of the nucleon, πN and the Δ resonance. The measurements explore a new, important parameter region of the exchanged virtual photon virtualities.

Published
2017
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240. Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions.

Author

Jo HS, Girod FX, Avakian H, Burkert VD, Garçon M, Guidal M, Kubarovsky V, Niccolai S, Stoler P, Adhikari KP, Adikaram D, Amaryan MJ, Anderson MD, Anefalos Pereira S, Ball J, Baltzell NA, Battaglieri M, Batourine V, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe WJ, Brooks WK, Carman DS, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Compton N, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Dupre R, Alaoui AE, Fassi LE, Elouadrhiri L, Fedotov G, Fegan S, Filippi A, Fleming JA, Garillon B, Gevorgyan N, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Goetz JT, Golovatch E, Gothe RW, Griffioen KA, Guegan B, Guler N, Guo L, Hafidi K, Hakobyan H, Harrison N, Hattawy M, Hicks K, Hirlinger Saylor N, Ho D, Holtrop M, Hughes SM, Ilieva Y, Ireland DG, Ishkhanov BS, Jenkins D, Joo K, Joosten S, Keller D, Khachatryan G, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Kuhn SE, Kuleshov SV, Lenisa P, Livingston K, Lu HY, MacGregor IJ, McKinnon B, Meziani ZE, Mirazita M, Mokeev V, Montgomery RA, Moutarde H, Movsisyan A, Munevar E, Munoz Camacho C, Nadel-Turonski P, Net LA, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Park K, Pasyuk E, Phillips JJ, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Puckett AJ, Raue BA, Ripani M, Rizzo A, Rosner G, Rossi P, Roy P, Sabatié F, Salgado C, Schott D, Schumacher RA, Seder E, Simonyan A, Skorodumina Iu, Smith GD, Sokhan D, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Sytnik V, Tian Y, Tkachenko S, Ungaro M, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zana L, Zhang J, Zhao ZW, and Zonta I

Abstract

Unpolarized and beam-polarized fourfold cross sections (d^{4}σ/dQ^{2}dx_{B}dtdϕ) for the ep→e^{'}p^{'}γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q^{2},x_{B},t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x_{B}.

Published
2015
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241. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton.

Author

Fanelli C, Cisbani E, Hamilton DJ, Salmé G, Wojtsekhowski B, Ahmidouch A, Annand JR, Baghdasaryan H, Beaufait J, Bosted P, Brash EJ, Butuceanu C, Carter P, Christy E, Chudakov E, Danagoulian S, Day D, Degtyarenko P, Ent R, Fenker H, Fowler M, Frlez E, Gaskell D, Gilman R, Horn T, Huber GM, de Jager CW, Jensen E, Jones MK, Kelleher A, Keppel C, Khandaker M, Kohl M, Kumbartzki G, Lassiter S, Li Y, Lindgren R, Lovelace H, Luo W, Mack D, Mamyan V, Margaziotis DJ, Markowitz P, Maxwell J, Mbianda G, Meekins D, Meziane M, Miller J, Mkrtchyan A, Mkrtchyan H, Mulholland J, Nelyubin V, Pentchev L, Perdrisat CF, Piasetzky E, Prok Y, Puckett AJ, Punjabi V, Shabestari M, Shahinyan A, Slifer K, Smith G, Solvignon P, Subedi R, Wesselmann FR, Wood S, Ye Z, and Zheng X

Abstract

Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

Published
2015
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242. Towards a resolution of the proton form factor problem: new electron and positron scattering data.

Author

Adikaram D, Rimal D, Weinstein LB, Raue B, Khetarpal P, Bennett RP, Arrington J, Brooks WK, Adhikari KP, Afanasev AV, Amaryan MJ, Anderson MD, Anefalos Pereira S, Avakian H, Ball J, Battaglieri M, Bedlinskiy I, Biselli AS, Bono J, Boiarinov S, Briscoe WJ, Burkert VD, Carman DS, Careccia S, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Dodge GE, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Filippi A, Fleming JA, Fradi A, Garillon B, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gohn W, Golovatch E, Gothe RW, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Hanretty C, Harrison N, Hattawy M, Hicks K, Holtrop M, Hughes SM, Hyde CE, Ilieva Y, Ireland DG, Ishkhanov BS, Jenkins D, Jiang H, Jo HS, Joo K, Joosten S, Kalantarians N, Keller D, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Koirala S, Kubarovsky V, Kuhn SE, Livingston K, Lu HY, MacGregor IJ, Markov N, Mattione P, Mayer M, McKinnon B, Mestayer MD, Meyer CA, Mirazita M, Mokeev V, Montgomery RA, Moody CI, Moutarde H, Movsisyan A, Camacho CM, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Peña C, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Protopopescu D, Puckett AJ, Ripani M, Rizzo A, Rosner G, Rossi P, Roy P, Sabatié F, Salgado C, Schott D, Schumacher RA, Seder E, Sharabian YG, Simonyan A, Skorodumina I, Smith ES, Smith GD, Sober DI, Sokhan D, Sparveris N, Stepanyan S, Stoler P, Strauch S, Sytnik V, Taiuti M, Tian Y, Trivedi A, Ungaro M, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Wood MH, Zachariou N, Zana L, Zhang J, Zhao ZW, and Zonta I

Abstract

There is a significant discrepancy between the values of the proton electric form factor, G(E)(p), extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of G(E)(p) from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ϵ) and momentum transfer (Q(2)) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ϵ at Q(2)=1.45  GeV(2). This measurement is consistent with the size of the form factor discrepancy at Q(2)≈1.75  GeV(2) and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3  GeV(2).

Published
2015
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243. Longitudinal target-spin asymmetries for deeply virtual compton scattering.

Author

Seder E, Biselli A, Pisano S, Niccolai S, Smith GD, Joo K, Adhikari K, Amaryan MJ, Anderson MD, Anefalos Pereira S, Avakian H, Battaglieri M, Bedlinskiy I, Bono J, Boiarinov S, Bosted P, Briscoe W, Brock J, Brooks WK, Bültmann S, Burkert VD, Carman DS, Carlin C, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Contalbrigo M, Crabb D, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Doughty D, Dupre R, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Filippi A, Fleming JA, Fradi A, Garillon B, Garçon M, Gevorgyan N, Ghandilyan Y, Giovanetti KL, Girod FX, Goetz JT, Gohn W, Gothe RW, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Hanretty C, Harrison N, Hattawy M, Hirlinger Saylor N, Holtrop M, Hughes SM, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Joosten S, Keith CD, Keller D, Khachatryan G, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Koirala S, Kubarovsky V, Kuhn SE, Lenisa P, Livingston K, Lu HY, MacGregor IJ, Markov N, Mayer M, McKinnon B, Meekins DG, Mineeva T, Mirazita M, Mokeev V, Montgomery R, Moody CI, Moutarde H, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Niculescu I, Osipenko M, Ostrovidov AI, Paolone M, Pappalardo LL, Park K, Park S, Pasyuk E, Peng P, Phelps W, Pogorelko O, Price JW, Prok Y, Protopopescu D, Puckett AJ, Ripani M, Rizzo A, Rosner G, Rossi P, Roy P, Sabatié F, Salgado C, Schott D, Schumacher RA, Senderovich I, Simonyan A, Skorodumina I, Sokhan D, Sparveris N, Stepanyan S, Stoler P, Strakovsky II, Strauch S, Sytnik V, Taiuti M, Tang W, Tian Y, Ungaro M, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zana L, Zhang J, and Zonta I

Abstract

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep→e^{'}p^{'}γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ϕ, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

Published
2015
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244. Nuclear physics. Momentum sharing in imbalanced Fermi systems.

Author

Hen O, Sargsian M, Weinstein LB, Piasetzky E, Hakobyan H, Higinbotham DW, Braverman M, Brooks WK, Gilad S, Adhikari KP, Arrington J, Asryan G, Avakian H, Ball J, Baltzell NA, Battaglieri M, Beck A, May-Tal Beck S, Bedlinskiy I, Bertozzi W, Biselli A, Burkert VD, Cao T, Carman DS, Celentano A, Chandavar S, Colaneri L, Cole PL, Crede V, D'Angelo A, De Vita R, Deur A, Djalali C, Doughty D, Dugger M, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Fedotov G, Fegan S, Forest T, Garillon B, Garcon M, Gevorgyan N, Ghandilyan Y, Gilfoyle GP, Girod FX, Goetz JT, Gothe RW, Griffioen KA, Guidal M, Guo L, Hafidi K, Hanretty C, Hattawy M, Hicks K, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Ishkanov BI, Isupov EL, Jiang H, Jo HS, Joo K, Keller D, Khandaker M, Kim A, Kim W, Klein FJ, Koirala S, Korover I, Kuhn SE, Kubarovsky V, Lenisa P, Levine WI, Livingston K, Lowry M, Lu HY, MacGregor IJ, Markov N, Mayer M, McKinnon B, Mineeva T, Mokeev V, Movsisyan A, Munoz Camacho C, Mustapha B, Nadel-Turonski P, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Pappalardo LL, Paremuzyan R, Park K, Pasyuk E, Phelps W, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Protopopescu D, Puckett AJ, Rimal D, Ripani M, Ritchie BG, Rizzo A, Rosner G, Roy P, Rossi P, Sabatié F, Schott D, Schumacher RA, Sharabian YG, Smith GD, Shneor R, Sokhan D, Stepanyan SS, Stepanyan S, Stoler P, Strauch S, Sytnik V, Taiuti M, Tkachenko S, Ungaro M, Vlassov AV, Voutier E, Walford NK, Wei X, Wood MH, Wood SA, Zachariou N, Zana L, Zhao ZW, Zheng X, and Zonta I

Abstract

The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using (12)C, (27)Al, (56)Fe, and (208)Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems., (Copyright © 2014, American Association for the Advancement of Science.)

Published
2014
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245. Measurement of exclusive π(0) electroproduction structure functions and their relationship to transverse generalized parton distributions.

Author

Bedlinskiy I, Kubarovsky V, Niccolai S, Stoler P, Adhikari KP, Aghasyan M, Amaryan MJ, Anghinolfi M, Avakian H, Baghdasaryan H, Ball J, Baltzell NA, Battaglieri M, Bennett RP, Biselli AS, Bookwalter C, Boiarinov S, Briscoe WJ, Brooks WK, Burkert VD, Carman DS, Celentano A, Chandavar S, Charles G, Contalbrigo M, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Doughty D, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Fleming JA, Forest TA, Fradi A, Garçon M, Gevorgyan N, Giovanetti KL, Girod FX, Gohn W, Gothe RW, Graham L, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Hanretty C, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Joo K, Keller D, Khandaker M, Khetarpal P, Kim A, Kim W, Klein FJ, Koirala S, Kubarovsky A, Kuhn SE, Kuleshov SV, Kvaltine ND, Livingston K, Lu HY, MacGregor IJ, Mao Y, Markov N, Martinez D, Mayer M, McKinnon B, Meyer CA, Mineeva T, Mirazita M, Mokeev V, Moutarde H, Munevar E, Munoz Camacho C, Nadel-Turonski P, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Pappalardo LL, Paremuzyan R, Park K, Park S, Pasyuk E, Anefalos Pereira S, Phelps E, Pisano S, Pogorelko O, Pozdniakov S, Price JW, Procureur S, Prok Y, Protopopescu D, Puckett AJ, Raue BA, Ricco G, Rimal D, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salgado C, Saylor N, Schott D, Schumacher RA, Seder E, Seraydaryan H, Sharabian YG, Smith GD, Sober DI, Sokhan D, Stepanyan SS, Stepanyan S, Strauch S, Taiuti M, Tang W, Taylor CE, Tian Y, Tkachenko S, Ungaro M, Vineyard MF, Vlassov A, Voskanyan H, Voutier E, Walford NK, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zachariou N, Zhang J, Zhao ZW, and Zonta I

Abstract

Exclusive π(0) electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q(2), x(B), t, and ϕ(π), in the Q(2) range from 1.0 to 4.6  GeV(2), -t up to 2  GeV(2), and x(B) from 0.1 to 0.58. Structure functions σ(T)+ϵσ(L), σ(TT), and σ(LT) were extracted as functions of t for each of 17 combinations of Q(2) and x(B). The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates σ(T)+ϵσ(L) and fails to account for σ(TT) and σ(LT), while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive π(0) electroproduction offers direct experimental access to the transversity GPDs.

Published
2012
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246. Polarization components in π0 photoproduction at photon energies up to 5.6 GeV.

Author

Luo W, Brash EJ, Gilman R, Jones MK, Meziane M, Pentchev L, Perdrisat CF, Puckett AJ, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Ates O, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy ME, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Kang H, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Markowitz P, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nuruzzaman, Nedev S, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer PE, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Širca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Strakovsky II, Subedi R, Suleiman R, Tomasi-Gustafsson E, Vasiliev A, Veilleux M, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, and Zhu L

Abstract

We present new data for the polarization observables of the final state proton in the (1)H(γ,p)π(0) reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for π(0) scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E(γ)=5.6 GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π(0) scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment.

Published
2012
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247. Measurement of the neutron F2 structure function via spectator tagging with CLAS.

Author

Baillie N, Tkachenko S, Zhang J, Bosted P, Bültmann S, Christy ME, Fenker H, Griffioen KA, Keppel CE, Kuhn SE, Melnitchouk W, Tvaskis V, Adhikari KP, Adikaram D, Aghasyan M, Amaryan MJ, Anghinolfi M, Arrington J, Avakian H, Baghdasaryan H, Battaglieri M, Biselli AS, Branford D, Briscoe WJ, Brooks WK, Burkert VD, Carman DS, Celentano A, Chandavar S, Charles G, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Dey B, Djalali C, Dodge G, Domingo J, Doughty D, Dupre R, Dutta D, Ent R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Fradi A, Gabrielyan MY, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Gohn W, Golovatch E, Gothe RW, Graham L, Guegan B, Guidal M, Guler N, Guo L, Hafidi K, Heddle D, Hicks K, Holtrop M, Hungerford E, Hyde CE, Ilieva Y, Ireland DG, Ispiryan M, Isupov EL, Jawalkar SS, Jo HS, Kalantarians N, Khandaker M, Khetarpal P, Kim A, Kim W, King PM, Klein A, Klein FJ, Klimenko A, Kubarovsky V, Kuleshov SV, Kvaltine ND, Livingston K, Lu HY, MacGregor IJ, Mao Y, Markov N, McKinnon B, Mineeva T, Morrison B, Moutarde H, Munevar E, Nadel-Turonski P, Ni A, Niccolai S, Niculescu I, Niculescu G, Osipenko M, Ostrovidov AI, Pappalardo L, Park K, Park S, Pasyuk E, Anefalos Pereira S, Pisano S, Pozdniakov S, Price JW, Procureur S, Prok Y, Protopopescu D, Raue BA, Ricco G, Rimal D, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salgado C, Schott D, Schumacher RA, Seder E, Sharabian YG, Sober DI, Sokhan D, Stepanyan S, Stepanyan SS, Stoler P, Strauch S, Taiuti M, Tang W, Ungaro M, Vineyard MF, Voutier E, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zana L, and Zhao B

Abstract

We report on the first measurement of the F(2) structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲100 MeV/c and their angles to ≳100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F(2)(n) data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65

Published
2012
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248. New Measurement of the π0 radiative decay width.

Author

Larin I, McNulty D, Clinton E, Ambrozewicz P, Lawrence D, Nakagawa I, Prok Y, Teymurazyan A, Ahmidouch A, Asratyan A, Baker K, Benton L, Bernstein AM, Burkert V, Cole P, Collins P, Dale D, Danagoulian S, Davidenko G, Demirchyan R, Deur A, Dolgolenko A, Dzyubenko G, Ent R, Evdokimov A, Feng J, Gabrielyan M, Gan L, Gasparian A, Gevorkyan S, Glamazdin A, Goryachev V, Gyurjyan V, Hardy K, He J, Ito M, Jiang L, Kashy D, Khandaker M, Kingsberry P, Kolarkar A, Konchatnyi M, Korchin A, Korsch W, Kowalski S, Kubantsev M, Kubarovsky V, Li X, Martel P, Matveev V, Mecking B, Milbrath B, Minehart R, Miskimen R, Mochalov V, Mtingwa S, Overby S, Pasyuk E, Payen M, Pedroni R, Ritchie B, Rodrigues TE, Salgado C, Shahinyan A, Sitnikov A, Sober D, Stepanyan S, Stephens W, Underwood J, Vasiliev A, Vishnyakov V, Wood M, and Zhou S

Abstract

High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst)  eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.

Published
2011
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249. Search for effects beyond the born approximation in polarization transfer observables in e(over→)p elastic scattering.

Author

Meziane M, Brash EJ, Gilman R, Jones MK, Luo W, Pentchev L, Perdrisat CF, Puckett AJ, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Ates O, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy E, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Kang H, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Markowitz P, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nuruzzaman, Nedev S, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer PE, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Širca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Subedi R, Suleiman R, Tomasi-Gustafsson E, Vasiliev A, Vanderhaeghen M, Veilleux M, Wojtsekhowski BB, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, and Zhu L

Abstract

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G(E)/G(M), obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5  GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals μ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(ℓ) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε., (© 2011 American Physical Society)

Published
2011
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250. Measurement of single- and double-spin asymmetries in deep inelastic pion electroproduction with a longitudinally polarized target.

Author

Avakian H, Bosted P, Burkert VD, Elouadrhiri L, Adhikari KP, Aghasyan M, Amaryan M, Anghinolfi M, Baghdasaryan H, Ball J, Battaglieri M, Bedlinskiy I, Biselli AS, Branford D, Briscoe WJ, Brooks W, Carman DS, Casey L, Cole PL, Collins P, Crabb D, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Dey B, Dhamija S, Dickson R, Djalali C, Dodge G, Doughty D, Dupre R, El Alaoui A, Eugenio P, Fegan S, Fersch R, Forest TA, Fradi A, Gabrielyan MY, Gavalian G, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Gohn W, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Hafidi K, Hakobyan H, Hanretty C, Hassall N, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jawalkar SS, Jo HS, Joo K, Keller D, Khandaker M, Khetarpal P, Kim W, Klein A, Klein FJ, Konczykowski P, Kubarovsky V, Kuhn SE, Kuleshov SV, Kuznetsov V, Livingston K, Lu HY, Markov N, Mayer M, Martinez D, McAndrew J, McCracken ME, McKinnon B, Meyer CA, Mineeva T, Mirazita M, Mokeev V, Moreno B, Moriya K, Morrison B, Moutarde H, Munevar E, Nadel-Turonski P, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niroula MR, Osipenko M, Ostrovidov AI, Paremuzyan R, Park K, Park S, Pasyuk E, Pereira SA, Perrin Y, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Protopopescu D, Raue BA, Ricco G, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salamanca J, Salgado C, Schumacher RA, Seder E, Seraydaryan H, Sharabian YG, Sober DI, Sokhan D, Stepanyan SS, Stepanyan S, Stoler P, Strauch S, Suleiman R, Taiuti M, Tedeschi DJ, Tkachenko S, Ungaro M, Vernarsky B, Vineyard MF, Voutier E, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zhang J, Zhao B, and Zhao ZW

Abstract

We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ϕ have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2ϕ single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton.

Published
2010
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