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1. Measurement of parton distributions of strange quarks in the nucleon from charged-kaon production in deep-inelastic scattering on the deuteron

Author: A. Reischl, W. Augustyniak, R. Perez-Benito, B. Maiheu, Alessandra Fantoni, D. Veretennikov, M. Negodaev, B. Hommez, G. Ciullo, Tetsuya Hasegawa, M. Hoek, E. De Sanctis, V. A. Gapienko, W.H.A. Hesselink, B. Zihlmann, Y. Naryshkin, P. E. Reimer, A. Kisselev, J. G. Rubin, A. Brull, B. Tchuiko, M. Kopytin, Cynthia Marie Hadjidakis, Y. Miyachi, A. Nass, G. Gapienko, I. Lehmann, D. Hasch, A. López Ruiz, Z. Akopov, A. Elalaoui-Moulay, Frank Ellinghaus, C. Shearer, B. Seitz, A. Hillenbrand, Y. Imazu, E. Nappi, Y. Van Haarlem, Michael Tytgat, E. R. Kinney, Y. Holler, A. Airapetian, U. Elschenbroich, S. Taroian, P. Lenisa, David Mahon, Y. Salomatin, B. Marianski, A. Trzcinski, P. B. van der Nat, J. Burns, Shan Wang, F. Stinzing, Andreas Schäfer, H. E. Jackson, V. G. Krivokhijine, A. Funel, B. Q. Ma, J. J. M. Steijger, Michael Düren, G. van der Steenhoven, A. Osborne, M. Stancari, P. Zupranski, C. Riedl, S. E. Rock, P. Di Nezza, V. Vikhrov, L. Rubacek, R. De Leo, A. Rostomyan, K. Rith, C. B. Van Hulse, A. Borissov, A. R. Reolon, A. Avetissian, M. Capiluppi, P. Liebing, A. Ivanilov, S. Belostotski, G. Rosner, H. Böttcher, V. Bryzgalov, J. Dreschler, L. De Nardo, W. Yu, F. Garibaldi, Morgan Murray, G. Iarygin, Zhenyu Ye, E. C. Aschenauer, G. Hill, K. P. Schüler, Y. X. Ye, P.F. Dalpiaz, J. Stewart, I. Vilardi, Andreas Mussgiller, A. Andrus, M. Diefenthaler, V. Gharibyan, P. Tait, L. A. Linden-Levy, W.-D. Nowak, T. A. Shibata, E. Avetissian, M. Demey, Nicola Bianchi, R.O. Avakian, H. Marukyan, C. Bonomo, E. Cisbani, V. A. Kozlov, D. Reggiani, G. Schnell, F. Giordano, S. Joosten, J. Streit, I. M. Gregor, H. Ye, A. Jgoun, Arne Vandenbroucke, Riccardo Fabbri, L. Manfré, Stephen V. Gliske, H. Guler, M. Varanda, L. Felawka, X. R. Lu, L. Lagamba, S. Yen, G. P. Capitani, Ralf Kaiser, E. Steffens, G. Gavrilov, L. Lapikás, M. Contalbrigo, Martin Raithel, I. Sanjiev, Naomi C R Makins, M. Ehrenfried, Andrey V. Izotov, C. A. Miller, D. Gabbert, Tsutomu Kobayashi, M. Statera, S. Frullani, N. Pickert, Dirk Ryckbosch, D. Zeiler, C. Vogel, V. A. Korotkov, G. Elbakian, S. Lu, Y. J. Mao, P. Kravchenko, Adel Terkulov, T. Keri, L. L. Pappalardo, Hasko Stenzel, Wouter Deconinck, Valeria Muccifora, V. Mexner, A. Nagaitsev, N. Akopov, S. Yaschenko, Vitaly Shutov, H. P. Blok, Wolfgang Lorenzon, Ivana Hristova, R. Lamb, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education
Subjects: Quark, Particle physics, Strange quark, Nuclear and High Energy Physics, Nuclear Theory, FOS: Physical sciences, Parton, 01 natural sciences, NO, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), 13.60.-r, 13.88.+e, 14.20.Dh, 14.65.-q, 0103 physical sciences, ddc:530, SDG 14 - Life Below Water, 010306 general physics, Nuclear Experiment, Physics, 010308 nuclear & particles physics, Scattering, Deep inelastic scattering, Helicity, Strange matter, Physics and Astronomy, High Energy Physics::Experiment, Nucleon
Abstract: The momentum and helicity density distributions of the strange quark sea in the nucleon are obtained in leading order from charged-kaon production in deep-inelastic scattering on the deuteron. The distributions are extracted from spin-averaged K+/- multiplicities, and from K+/- and inclusive double-spin asymmetries for scattering of polarized positrons by a polarized deuterium target. The shape of the momentum distribution is softer than that of the average of the ubar and dbar quarks. In the region of measurement 0.02 < x < 0.6 and Q^2 > 1.0 GeV^2, the helicity distribution is zero within experimental uncertainties., 5 pages, 5 figures, 1 table; text slightly expanded, 10 references added
Published: 2008
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2. Hard exclusive electroproduction of π+π− pairs

Author: A. Airapetian, N. Akopov, Z. Akopov, M. Amarian, V.V. Ammosov, A. Andrus, E.C. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, D. Balin, V. Baturin, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H.P. Blok, H. Böttcher, A. Borissov, A. Borysenko, M. Bouwhuis, J. Brack, A. Brüll, V. Bryzgalov, G.P. Capitani, T. Chen, G. Ciullo, M. Contalbrigo, P.F. Dalpiaz, R. De Leo, M. Demey, L. De Nardo, E. De Sanctis, E. Devitsin, P. Di Nezza, M. Düren, M. Ehrenfried, A. Elalaoui-Moulay, G. Elbakian, F. Ellinghaus, U. Elschenbroich, R. Fabbri, A. Fantoni, A. Fechtchenko, L. Felawka, S. Frullani, G. Gapienko, V. Gapienko, F. Garibaldi, K. Garrow, E. Garutti, G. Gavrilov, V. Gharibyan, G. Graw, O. Grebeniouk, L.G. Greeniaus, I.M. Gregor, K.A. Griffioen, K. Hafidi, M. Hartig, D. Hasch, D. Heesbeen, M. Henoch, R. Hertenberger, W.H.A. Hesselink, A. Hillenbrand, M. Hoek, Y. Holler, B. Hommez, G. Iarygin, A. Ivanilov, A. Izotov, H.E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, M. Kopytin, V. Korotkov, V. Kozlov, B. Krauss, V.G. Krivokhijine, L. Lagamba, L. Lapikás, A. Laziev, P. Lenisa, P. Liebing, L.A. Linden-Levy, K. Lipka, W. Lorenzon, H. Lu, J. Lu, S. Lu, B.-Q. Ma, B. Maiheu, N.C.R. Makins, Y. Mao, B. Marianski, H. Marukyan, F. Masoli, V. Mexner, N. Meyners, O. Mikloukho, C.A. Miller, Y. Miyachi, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, M. Negodaev, W.-D. Nowak, K. Oganessyan, H. Ohsuga, A. Osborne, N. Pickert, S. Potashov, D.H. Potterveld, M. Raithel, D. Reggiani, P.E. Reimer, A. Reischl, A.R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, L. Rubacek, J. Rubin, D. Ryckbosch, Y. Salomatin, I. Sanjiev, I. Savin, A. Schäfer, C. Schill, G. Schnell, K.P. Schüler, J. Seele, R. Seidl, B. Seitz, R. Shanidze, C. Shearer, T.-A. Shibata, V. Shutov, K. Sinram, W. Sommer, M. Stancari, M. Statera, E. Steffens, J.J.M. Steijger, H. Stenzel, J. Stewart, F. Stinzing, P. Tait, H. Tanaka, S. Taroian, B. Tchuiko, A. Terkulov, A. Tkabladze, A. Trzcinski, M. Tytgat, A. Vandenbroucke, P. van der Nat, G. van der Steenhoven, Y. van Haarlem, M.C. Vetterli, V. Vikhrov, M.G. Vincter, C. Vogel, M. Vogt, J. Volmer, C. Weiskopf, J. Wendland, J. Wilbert, G. Ybeles Smit, Y. Ye, Z. Ye, S. Yen, B. Zihlmann, and P. Zupranski
Subjects: Physics, HERMES experiment, Nuclear and High Energy Physics, Particle physics, Meson, Isovector, 010308 nuclear & particles physics, Isoscalar, Nuclear Theory, Parton, 01 natural sciences, Helicity, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Invariant mass, Nuclear Experiment, 010306 general physics
Abstract: Hard exclusive electroproduction of π + π − pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY. Legendre moments 〈 P 1 〉 and 〈 P 3 〉 of the angular distributions of π + mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the π + π − invariant mass can be understood as being due to the interference between relative P -wave (isovector) and S -, D -wave (isoscalar) states of the two pions. The increase in magnitude of 〈 P 1 〉 as Bjorken x increases is interpreted in the framework of generalized parton distributions as an enhancement of flavour non-singlet q q ¯ exchange for larger values of x , which leads to a sizable admixture of isoscalar and isovector pion pairs. In addition, the interference between P -wave and D -wave states separately for transverse and longitudinal pion pairs has been studied. The data indicate that in the f 2 ( 1270 ) region at 〈 Q 2 〉 = 3 GeV 2 higher-twist effects can be as large as the leading-twist longitudinal component.
Published: 2004

3. Measurement of Azimuthal Asymmetries With Respect To Both Beam Charge and Transverse Target Polarization in Exclusive Electroproduction of Real Photons

Author: HERMES collaboration, A Airapetian, N Akopov, Z Akopov, A Andrus, E.C Aschenauer, W Augustyniak, R Avakian, A Avetissian, E Avetisyan, L Barion, S Belostotski, N Bianchi, H.P Blok, H Böttcher, C Bonomo, A Borissov, A Brüll, V Bryzgalov, J Burns, M Capiluppi, G.P Capitani, E Cisbani, G Ciullo, M Contalbrigo, P.F Dalpiaz, W Deconinck, R. De Leo, M Demey, L. De Nardo, E. De Sanctis, M Diefenthaler, P. Di Nezza, J Dreschler, M Düren, M Ehrenfried, G Elbakian, F Ellinghaus, U Elschenbroich, R Fabbri, A Fantoni, L Felawka, S Frullani, A Funel, D Gabbert, G Gapienko, V Gapienko, F Garibaldi, G Gavrilov, V Gharibyan, F Giordano, S Gliske, H Guler, C Hadjidakis, D Hasch, T Hasegawa, G Hill, A Hillenbrand, M Hoek, Y Holler, I Hristova, G Iarygin, Y Imazu, A Ivanilov, A Izotov, H.E Jackson, A Jgoun, S Joosten, R Kaiser, T Keri, E Kinney, A Kisselev, M Kopytin, V Korotkov, V Kozlov, P Kravchenko, V.G Krivokhijine, L Lagamba, R Lamb, L Lapikás, I Lehmann, P Lenisa, L.A Linden-Levy, W Lorenzon, S Lu, X Lu, B.-Q Ma, D Mahon, B Maiheu, N.C.R Makins, Y Mao, B Marianski, H Marukyan, C.A Miller, Y Miyachi, V Muccifora, M Murray, A Mussgiller, A Nagaitsev, E Nappi, Y Naryshkin, A Nass, M Negodaev, W.-D Nowak, A Osborne, L.L Pappalardo, R Perez-Benito, N Pickert, M Raithel, P.E Reimer, A Reischl, A.R Reolon, C Riedl, K Rith, S.E Rock, G Rosner, A Rostomyan, L Rubacek, J Rubin, A.L Ruiz, D Ryckbosch, Y Salomatin, I Sanjiev, A Schäfer, G Schnell, K.P Schüler, B Seitz, C Shearer, T.-A Shibata, V Shutov, M Stancari, M Statera, E Steffens, J.J.M Steijger, H Stenzel, J Stewart, F Stinzing, P Tait, S Taroian, A Terkulov, A Trzcinski, M Tytgat, A Vandenbroucke, P.B. van der Nat, G. van der Steenhoven, Y. Van Haarlem, C. Van Hulse, M Varanda, D Veretennikov, V Vikhrov, I Vilardi, C Vogel, S Wang, S Yaschenko, H Ye, Z Ye, S Yen, W Yu, D Zeiler, B Zihlmann, P Zupranski, (Astro)-Particles Physics, and Student Lab and Education
Subjects: Quark, Physics, Nuclear and High Energy Physics, Particle physics, Photon, 010308 nuclear & particles physics, media_common.quotation_subject, Lepton-Nucleon Scattering, Compton scattering, FOS: Physical sciences, Parton, Polarization (waves), 01 natural sciences, Asymmetry, NO, High Energy Physics - Experiment, Transverse plane, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, ddc:530, High Energy Physics::Experiment, 010306 general physics, Nucleon, Nuclear Experiment, media_common
Abstract: Azimuthal asymmetries in exclusive electroproduction of real photons are measured for the first time with respect to transverse target polarisation, providing new constraints on Generalized Parton Distributions. From the same data set on a hydrogen target, new results for the beam-charge asymmetry are also extracted with better precision than those previously reported. By comparing model calculations with measured asymmetries attributed to the interference between the deeply virtual Compton scattering and Bethe-Heitler processes, a model-dependent constraint is obtained on the total angular momenta carried by up and down quarks in the nucleon., 24 pages, 10 figures, 2 tables; 1 figure,3 references added, slight text change
Published: 2008

4. Transverse polarization ofΛandΛ¯hyperons in quasireal photoproduction

Author: I. Brunn, A. Kisselev, J. Wilbert, W. Augustyniak, Alessandra Fantoni, G. Graw, B. D. Fox, B. Zihlmann, M. Stancari, V. Mexner, B. Tchuiko, M. Kopytin, A. Nass, G. Schnell, O. Grebeniouk, A. Nagaitsev, B. Hommez, P. E. Reimer, P. Lenisa, J. Seibert, A. Trzcinski, Michel Vetterli, M. Henoch, E. Thomas, A. Laziev, M. Vogt, D. Reggiani, N. Akopov, B. Seitz, S. Tessarin, P. B. van der Nat, Katerina Lipka, K. Oganessyan, G. Iarygin, F. Masoli, J. Visser, A. Jgoun, V. A. Gapienko, G. M. Urciuoli, H. Kolster, Dirk Ryckbosch, M. Amarian, V. Vikhrov, Adel Terkulov, R. Van de Vyver, S. Belostotski, Manuella Vincter, H. Marukyan, Hidekazu Tanaka, M. Statera, Rezo Shanidze, J. Franz, Salvatore Frullani, Y. Gärber, J. Stewart, L. G. Greeniaus, V. A. Korotkov, A. Brüll, F. Menden, P. F. Dalpiaz, V. V. Ammosov, S. Yen, H. E. Jackson, A. Tkabladze, V. G. Krivokhijine, Andrey V. Izotov, C. Weiskopf, Ralf Kaiser, H. P. Blok, H. C. Chiang, C. Baumgarten, Ralf Hertenberger, S. Yoneyama, C. A. Miller, Valeria Muccifora, E. Steffens, G. Gavrilov, B. Krauss, C. Scarlett, Wolfgang Lorenzon, J. Ely, K. Königsmann, V. Baturin, V. A. Kozlov, M. Ehrenfried, S. Potashov, E. De Sanctis, Franco Garibaldi, H. Zohrabian, W.H.A. Hesselink, R. De Leo, A. Fechtchenko, D. Veretennikov, G. Elbakian, Erika Garutti, S. Bernreuther, M. Bouwhuis, A. Airapetian, H. Böttcher, Michael Tytgat, A. Andrus, S. Taroian, A. Elalaoui-Moulay, Frank Ellinghaus, A. Borissov, P. Di Nezza, P. Liebing, E. R. Kinney, M. Contalbrigo, A. Schwind, Martin Raithel, E. C. Aschenauer, Y. Naryshkin, L. Felawka, V. Shutov, U. Elschenbroich, I. Sanjiev, G. Orlandi, K. P. Schüler, Naomi C R Makins, D. Gaskell, A. Hillenbrand, G. P. Capitani, E. Avetissian, Nicola Bianchi, O. Mikloukho, P. Bailey, U. Stosslein, L. Lagamba, Z. Akopov, Y. Miyachi, P. Zupranski, J. Wendland, D. Hasch, D. H. Potterveld, R. Fabbri, T. A. Shibata, G. Gapienko, R.O. Avakian, N. Meyners, G. Rosner, E. Devitsin, K. Sinram, H. Ohsuga, L. De Nardo, V. Gharibyan, A. Rostomyan, A. R. Reolon, A. Avetissian, J. Volmer, J. J. M. Steijger, Michael Düren, K. Hafidi, Y. Holler, M. C. Simani, A. Reischl, G. Ciullo, Christian Schill, Eugenio Nappi, M. Hartig, T. Wise, M. Beckmann, L. Lapikás, Jeffrey Brack, W. Haeberli, Klaus Rith, D. Heesbeen, G. van der Steenhoven, T. Lindemann, I.A. Savin, G.R. Court, Andreas Schäfer, and W.-D. Nowak
Subjects: Physics, HERMES experiment, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Hyperon, Lambda, Lambda baryon, Polarization (waves), 01 natural sciences, Particle identification, Nuclear physics, Transverse plane, Light cone, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract: The HERMES experiment has measured the transverse polarization of Lambda and {ovr Lambda} hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P{sub n}{sup Lambda} of the Lambda hyperon is found to be positive while the observed {ovr Lambda} polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P{sub n}{sup Lambda} =0.078 {+-} 0.006(stat) {+-} 0.012(syst) and P{sub n}{sup {ovr Lambda}} = -0.025 {+-} 0.015(stat) {+-} 0.018(syst) for Lambda and {ovr Lambda}, respectively. The dependences of P{sub n}{sup Lambda} and P{sub n}{sup {ovr Lambda}} on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p{sub T} were investigated. The measured Lambda polarization rises linearly with p{sub T} and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.
Published: 2007

5. Precise determination of the spin structure function g(1) of the proton, deuteron, and neutron

Author: L. A. Linden-Levy, W.-D. Nowak, V. A. Gapienko, P. Zupranski, J. Streit, L. Felawka, I.A. Savin, N. Meyners, G. Rosner, W. Augustyniak, Shan Wang, G. P. Capitani, H. Böttcher, Andreas Schäfer, N. Bianchi, L. Rubacek, L. Lapikás, D. Veretennikov, G. Schnell, A. Funel, A. Nagaitsev, G. van der Steenhoven, A. Osborne, Salvatore Frullani, U. Stosslein, H. Ohsuga, Arne Vandenbroucke, L. Lagamba, Z. Akopov, Riccardo Fabbri, J. G. Rubin, P. F. Dalpiaz, Y. Naryshkin, Hidekazu Tanaka, G. Iarygin, P. Tait, Morgan Murray, T. A. Shibata, R.O. Avakian, Tetsuya Hasegawa, F. Giordano, A. Rostomyan, A. R. Reolon, Tsutomu Kobayashi, Y. Salomatin, M. Contalbrigo, A. Avetissian, P. Lenisa, A. Trzcinski, H. E. Jackson, H. Marukyan, N. Akopov, V. G. Krivokhijine, A. Airapetian, H. P. Blok, Y. X. Ye, M. Statera, A. Brull, B. Marianski, Martin Raithel, E. Devitsin, Wolfgang Lorenzon, E. C. Aschenauer, V. Shutov, A. Kisselev, B. Q. Ma, K. Garrow, Ivana Hristova, Hasko Stenzel, M. Capiluppi, C. Vogel, B. Hommez, C. Weiskopf, Alessandra Fantoni, M. Hoek, I. Sanjiev, G. Gapienko, F. Stinzing, J. Stewart, V. A. Kozlov, D. Reggiani, M. Ehrenfried, K. Rith, R. De Leo, P. E. Reimer, V. A. Korotkov, Michael Tytgat, Naomi C R Makins, R. Perez-Benito, B. Tchuiko, M. Kopytin, B. Maiheu, J. Dreschler, V. Vikhrov, M. Hartig, M. Demey, O. Grebeniouk, M. Stancari, Wouter Deconinck, P. Di Nezza, S. Taroian, P. Liebing, J. Lu, I. M. Gregor, Andrey V. Izotov, A. Jgoun, S. Yen, C. Shearer, B. Seitz, A. Borissov, Valeria Muccifora, C. Riedl, Ralf Kaiser, U. Elschenbroich, W.H.A. Hesselink, Y. Van Haarlem, M. Diefenthaler, E. Steffens, J. Seele, P. B. van der Nat, K. P. Schüler, E. De Sanctis, T. Michler, G. Elbakian, Franco Garibaldi, A. Hillenbrand, G. Gavrilov, H. Guler, A. Borysenko, A. Gute, A. Andrus, Eugenio Nappi, V. Mexner, E. Avetissian, N. Pickert, O. Mikloukho, Dirk Ryckbosch, M. Negodaev, S. Lu, Adel Terkulov, C. A. Miller, Y. Gärber, D. Gabbert, Y. J. Mao, P. Kravchenko, F. Masoli, T. Keri, J. J. M. Steijger, Michael Düren, A. Elalaoui-Moulay, Frank Ellinghaus, B. Zihlmann, E. R. Kinney, Cynthia Marie Hadjidakis, Y. Miyachi, D. Hasch, S. Belostotski, V. Bryzgalov, K. Sinram, L. De Nardo, Zhenyu Ye, V. Gharibyan, A. Reischl, B. Krauss, G. Ciullo, Y. Holler, A. Ivanilov, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education
Subjects: Physics, HERMES experiment, Nuclear and High Energy Physics, Proton, FOS: Physical sciences, 14.20.Dh, 13.88.+e, 13.60.Hb, 13.60.−r, HERA, Inelastic scattering, High Energy Physics - Experiment, NO, Nuclear physics, High Energy Physics - Experiment (hep-ex), Deuterium, High Energy Physics::Experiment, Neutron, ddc:530, Atomic physics, Nuclear Experiment, Nucleon, Spin-½
Abstract: Precise measurements of the spin structure functions of the proton $g_1^p(x,Q^2)$ and deuteron $g_1^d(x,Q^2)$ are presented over the kinematic range $0.0041 \leq x \leq 0.9$ and $0.18 $ GeV$^2$ $\leq Q^2 \leq 20$ GeV$^2$. The data were collected at the HERMES experiment at DESY, in deep-inelastic scattering of 27.6 GeV longitudinally polarized positrons off longitudinally polarized hydrogen and deuterium gas targets internal to the HERA storage ring. The neutron spin structure function $g_1^n$ is extracted by combining proton and deuteron data. The integrals of $g_1^{p,d}$ at $Q^2=5$ GeV$^2$ are evaluated over the measured $x$ range. Neglecting any possible contribution to the $g_1^d$ integral from the region $x \leq 0.021$, a value of $0.330 \pm 0.011\mathrm{(theo.)}\pm0.025\mathrm{(exp.)}\pm 0.028$(evol.) is obtained for the flavor-singlet axial charge $a_0$ in a leading-twist NNLO analysis.
Published: 2007

6. Beam-charge azimuthal asymmetry and deeply virtual Compton scattering

Author: A. Airapetian, A. Reischl, L. Lagamba, C. Shearer, B. Seitz, Z. Akopov, Shan Wang, H. Ohsuga, Klaus Rith, U. Elschenbroich, F. Stinzing, P. B. van der Nat, H. Y. Lu, A. Borissov, V. A. Gapienko, A. Nagaitsev, S. Frullani, G. Ciullo, M. Demey, C. A. Miller, N. Pickert, Dirk Ryckbosch, A. Rostomyan, A. R. Reolon, A. Avetissian, P. F. Dalpiaz, V. A. Korotkov, G. Iarygin, I. M. Gregor, R. Seidl, Hidekazu Tanaka, M. Stancari, M. Beckmann, A. Elalaoui-Moulay, Frank Ellinghaus, W.-D. Nowak, E. R. Kinney, M. Statera, A. Laziev, P. E. Reimer, K. Garrow, N. Akopov, L. Rubacek, Andrey V. Izotov, M. Bouwhuis, H. Böttcher, V. A. Kozlov, J. Seele, Valeria Muccifora, H. Marukyan, A. Osborne, Y. Naryshkin, Y. X. Ye, G. Gapienko, A. Hillenbrand, G. Elbakian, J. Volmer, Alessandra Fantoni, A. Funel, M. Hoek, A. Ivanilov, J. Stewart, K. P. Schüler, P. Zupranski, Y. J. Mao, P. Tait, B. Maiheu, A. Brull, B. Tchuiko, M. Kopytin, M. Contalbrigo, Tsutomu Kobayashi, L. Felawka, M. Amarian, W. Augustyniak, A. Andrus, Martin Raithel, Eugenio Nappi, E. De Sanctis, T. Michler, Y. Salomatin, S. Lu, E. C. Aschenauer, J. J. M. Steijger, M. Negodaev, Michael Düren, G. van der Steenhoven, V. Shutov, B. Krauss, G. P. Capitani, Adel Terkulov, I. Sanjiev, F. Masoli, Naomi C R Makins, Michael Tytgat, E. Avetissian, D. Balin, Nicola Bianchi, O. Mikloukho, W.H.A. Hesselink, G. Schnell, T. Chen, D. Gaskell, A. Jgoun, B. Q. Ma, H. E. Jackson, M. Hartig, N. Meyners, G. Rosner, L. A. Linden-Levy, K. Oganessyan, Y. Holler, S. Taroian, A. Borysenko, V. G. Krivokhijine, M. Ehrenfried, B. Marianski, J. Lu, C. Vogel, S. Yen, P. Lenisa, R. De Leo, Rezo Shanidze, A. Trzcinski, Ralf Kaiser, S. Belostotski, V. Bryzgalov, Wouter Deconinck, P. Di Nezza, F. Garibaldi, P. Liebing, E. Steffens, J. Dreschler, G. Gavrilov, V. Vikhrov, K. Sinram, L. De Nardo, Zhenyu Ye, Manuella Vincter, Hasko Stenzel, M. Capiluppi, L. Lapikás, I.A. Savin, J. G. Rubin, V. Gharibyan, V. Mexner, K. Hafidi, Morgan Murray, Y. Van Haarlem, B. Zihlmann, P. Bailey, T. A. Shibata, Cynthia Marie Hadjidakis, Y. Miyachi, R.O. Avakian, Andreas Schäfer, J. Wendland, W. Sommer, D. Hasch, D. H. Potterveld, E. Devitsin, A. Kisselev, Arne Vandenbroucke, Riccardo Fabbri, D. Reggiani, O. Grebeniouk, C. Riedl, H. P. Blok, Wolfgang Lorenzon, Ivana Hristova, B. Hommez, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: HERMES experiment, Elastic scattering, Physics, Nuclear and High Energy Physics, Particle physics, Photon, Scattering, media_common.quotation_subject, High Energy Physics::Phenomenology, Compton scattering, FOS: Physical sciences, DESY, HERA, 13.60.Fz Elastic and Compton scattering, 14.20.Dh, 24.85.+p, Asymmetry, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), ddc:530, High Energy Physics::Experiment, Nuclear Experiment, media_common
Abstract: The first observation of an azimuthal cross section asymmetry with respect to the charge of the incoming lepton beam is reported from a study of hard exclusive electroproduction of real photons. The data have been accumulated by the HERMES experiment at DESY, in which the HERA 27.6 GeV electron or positron beam scattered off an unpolarized hydrogen gas target. The observed asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply virtual Compton scattering (DVCS) process. The interference term is sensitive to DVCS amplitudes, which provide the most direct access to generalized parton distributions. © 2007 The American Physical Society.
Published: 2007

7. Beam-spin asymmetries in the azimuthal distribution of pion electroproduction

Author: V. A. Korotkov, Wouter Deconinck, V. Mexner, J. Lu, S. Yen, B. Zihlmann, G. Elbakian, Y. Miyachi, H. Guler, Ralf Kaiser, B. Hommez, A. Nagaitsev, A. Borissov, M. Demey, G. Iarygin, H. Marukyan, E. Steffens, Dirk Ryckbosch, Hasko Stenzel, A. Airapetian, P. Lenisa, I.A. Savin, I. M. Gregor, V. Kozlov, A. Brull, G. Gavrilov, J. G. Rubin, A. Andrus, A. Trzcinski, B. Marianski, K. Sinram, L. De Nardo, T. Keri, Tsutomu Kobayashi, Y. J. Mao, P. Kravchenko, O. Grebeniouk, A. Elalaoui-Moulay, Frank Ellinghaus, E. R. Kinney, S. Lu, Y. Naryshkin, M. Negodaev, G.P. Capitani, M. Statera, S. Frullani, F. Stinzing, H. E. Jackson, V. G. Krivokhijine, Andreas Schäfer, N. Pickert, L. Felawka, M. Amarian, H. P. Blok, A. R. Reolon, T. A. Shibata, Adel Terkulov, C. Vogel, A. Funel, W.H.A. Hesselink, V. Muccifora, V. Vikhrov, J. J. M. Steijger, Michael Düren, Michael Tytgat, Y. Salomatin, Wolfgang Lorenzon, M. Stancari, P. E. Reimer, L. Lagamba, P. Di Nezza, P. Bailey, G. van der Steenhoven, C. A. Miller, Arne Vandenbroucke, P. Zupranski, Morgan Murray, R.O. Avakian, L. Rubacek, Riccardo Fabbri, B. Krauss, S. Taroian, K. P. Schüler, A. Fantoni, Ivana Hristova, H. Avakian, P.F. Dalpiaz, B. Q. Ma, A. Borysenko, F. Giordano, Alessandro Bacchetta, W. Augustyniak, M. Contalbrigo, E. Devitsin, O. Mikloukho, M. Ehrenfried, N. Meyners, Martin Raithel, W.-D. Nowak, R. De Leo, J. Stewart, K. Garrow, G. Rosner, E. C. Aschenauer, A. Kisselev, V. Shutov, A. Osborne, R. Seidl, E. Avetisyan, E. De Sanctis, T. Michler, Klaus Rith, V. Gharibyan, K. Oganessyan, I. Sanjiev, H. Böttcher, Naomi C R Makins, J. Streit, F. Masoli, S. Belostotski, D. Reggiani, M. Hartig, V. Bryzgalov, F. Garibaldi, C. Hadjidakis, P. Tait, J. Dreschler, M. Capiluppi, P. Liebing, Andrey V. Izotov, Z. Akopov, D. Hasch, Z. Ye, Hidekazu Tanaka, A. Jgoun, Y. Van Haarlem, C. Riedl, G. Gapienko, Shan Wang, H. Ohsuga, A. Rostomyan, A. Avetissian, K. Hafidi, M. Diefenthaler, J. Seele, A. Hillenbrand, A. Ivanilov, A. Reischl, Y. Holler, G. Ciullo, Tetsuya Hasegawa, V. A. Gapienko, N. Bianchi, R. Perez-Benito, B. Maiheu, C. Shearer, B. Seitz, E. Nappi, U. Elschenbroich, L. Lapikás, P. B. van der Nat, Y. X. Ye, L. A. Linden-Levy, M. Hoek, G. Schnell, B. Tchuiko, M. Kopytin, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education
Subjects: Nuclear and High Energy Physics, Meson, Hadron, FOS: Physical sciences, Virtual particle, Inelastic scattering, 01 natural sciences, 7. Clean energy, 24.85.+p, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, 13.88.+e, 0103 physical sciences, ddc:530, SDG 7 - Affordable and Clean Energy, 010306 general physics, Nuclear Experiment, 13.60.-r, Physics, 010308 nuclear & particles physics, 13.87.Fh, 14.20.Dh, HERA, Science General, Scattering amplitude, Physics::Accelerator Physics, High Energy Physics::Experiment, Dimensionless quantity
Abstract: A measurement of the beam-spin asymmetry in the azimuthal distribution of pions produced in semi-inclusive deep-inelastic scattering off protons is presented. The measurement was performed using the HERMES spectrometer with a hydrogen gas target and the longitudinally polarized 27.6 GeV positron beam of HERA. The sinusoidal amplitude of the dependence of the asymmetry on the angle ϕ of the hadron production plane around the virtual photon direction relative to the lepton scattering plane was measured for π + π + , π − π − and π 0 π 0 mesons. The dependence of this amplitude on the Bjorken scaling variable and on the pion fractional energy and transverse momentum is presented. The results are compared to theoretical model calculations.
Published: 2007

8. Double-hadron leptoproduction in the nuclear medium

Author: V. A. Korotkov, Klaus Rith, M. Stancari, J. Stewart, J. J. M. Steijger, A. Brüll, Michael Düren, G. Elbakian, D. Veretennikov, A. Airapetian, B. Zihlmann, K. Sinram, L. De Nardo, Zhenyu Ye, V. Gharibyan, W. Augustyniak, Cynthia Marie Hadjidakis, Y. Miyachi, D. Hasch, A. Funel, F. Giordano, P. Di Nezza, G. van der Steenhoven, M. Demey, Shan Wang, H. Ohsuga, A. Osborne, P. Liebing, R. Seidl, F. Stinzing, Hasko Stenzel, V. A. Gapienko, I. M. Gregor, G. Iarygin, M. Capiluppi, P. Lenisa, L. A. Linden-Levy, H. Böttcher, Michael Tytgat, A. Trzcinski, W.H.A. Hesselink, W.-D. Nowak, Tsutomu Kobayashi, A. Borysenko, H. Marukyan, J. G. Rubin, A. Rostomyan, A. Avetissian, S. Taroian, L. Lapikás, Dirk Ryckbosch, B. Hommez, Frank Ellinghaus, J. Streit, S. Lu, Adel Terkulov, G. Gapienko, I.A. Savin, E. R. Kinney, O. Grebeniouk, C. Riedl, C. Vogel, Salvatore Frullani, P. Tait, P. Bailey, L. Lagamba, H. Guler, Z. Akopov, Y. Naryshkin, P. F. Dalpiaz, Eugenio Nappi, A. Borissov, V. Vikhrov, A. R. Roelon, J. Dreschler, Hidekazu Tanaka, R. Perez-Benito, B. Maiheu, A. Andrus, H. E. Jackson, Andreas Schäfer, H. P. Blok, M. Negodaev, Morgan Murray, A. Jgoun, B. Krauss, Y. Van Haarlem, B. Marianski, Wolfgang Lorenzon, Tetsuya Hasegawa, Valeria Muccifora, Ivana Hristova, Y. Salomatin, K. P. Schüler, S. Belostotski, P. Zupranski, B. Q. Ma, V. Bryzgalov, M. Ehrenfried, R. De Leo, E. Avetissian, Nicola Bianchi, O. Mikloukho, Arne Vandenbroucke, N. Meyners, G. Rosner, Riccardo Fabbri, I. Sanjiev, K. Garrow, V. A. Kozlov, L. Felawka, M. Amarian, A. Nagaitsev, G. P. Capitani, G. Schnell, N. Akopov, Y. J. Mao, P. Kravchenko, V. G. Krivokhijine, F. Masoli, P. E. Reimer, M. Contalbrigo, Y. X. Ye, Martin Raithel, E. C. Aschenauer, V. Shutov, C. Shearer, B. Seitz, Naomi C R Makins, U. Elschenbroich, T. Keri, P. B. van der Nat, M. Hartig, J. Lu, Alessandra Fantoni, Wouter Deconinck, S. Yen, M. Hoek, K. A. Griffioen, Ralf Kaiser, B. Tchuiko, M. Kopytin, E. Steffens, G. Gavrilov, V. Mexner, T. A. Shibata, R.O. Avakian, A. Ivanilov, A. Reischl, E. Devitsin, A. Kisselev, G. Ciullo, D. Reggiani, Y. Holler, E. De Sanctis, T. Michler, Franco Garibaldi, M. Diefenthaler, J. Seele, A. Hillenbrand, N. Pickert, C. A. Miller, A. Elalaoui-Moulay, M. Statera, Andrey V. Izotov, L. Rubacek, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education
Subjects: Particle physics, Nuclear Theory, FOS: Physical sciences, General Physics and Astronomy, chemistry.chemical_element, Inelastic scattering, 25.30.Rw, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Xenon, ddc:550, 13.60.−r, 13.87.Fh, 25.75.Gz, Nuclear Experiment, Physics, Scattering, High Energy Physics::Phenomenology, Krypton, HERA, Nuclear matter, Deep inelastic scattering, chemistry, Deuterium, High Energy Physics::Experiment
Abstract: Physical review letters 96, 162301 (2006). doi:10.1103/PhysRevLett.96.162301, Published by APS, College Park, Md.
Published: 2006

9. Longitudinal spin transfer to the Lambda hyperon in semiinclusive deep-inelastic scattering

Author: B. Hommez, B. Marianski, K. Sinram, L. De Nardo, A. Osborne, B. Krauss, Zhenyu Ye, Y. Van Haarlem, A. Borissov, V. Gharibyan, K. Hafidi, R. Seidl, P. E. Reimer, M. Bouwhuis, H. Böttcher, M. Diefenthaler, Morgan Murray, G. Iarygin, J. Seele, B. Zihlmann, V. Vikhrov, Manuella Vincter, A. Hillenbrand, Houbing Lu, P. Tait, J. Dreschler, A. Andrus, Cynthia Marie Hadjidakis, Y. Miyachi, J. Wendland, W. Sommer, M. Demey, M. Negodaev, D. Hasch, D. H. Potterveld, Dirk Ryckbosch, H. Marukyan, S. Belostotski, V. Bryzgalov, P. Bailey, I. M. Gregor, Y. Salomatin, Tsutomu Kobayashi, W. Augustyniak, M. Statera, Arne Vandenbroucke, Riccardo Fabbri, C. Vogel, B. Q. Ma, H. P. Blok, M. Beckmann, M. Ehrenfried, R. De Leo, Wolfgang Lorenzon, Andrey V. Izotov, Klaus Rith, J. J. M. Steijger, Michael Düren, T. A. Shibata, V. A. Korotkov, R.O. Avakian, A. Elalaoui-Moulay, Frank Ellinghaus, H. Ohsuga, Ivana Hristova, E. R. Kinney, M. Stancari, A. Jgoun, E. Devitsin, C. Riedl, Y. Naryshkin, Michael Tytgat, H. E. Jackson, A. Kisselev, V. G. Krivokhijine, A. Brüll, P. Lenisa, A. Trzcinski, N. Pickert, D. Reggiani, W.-D. Nowak, G. Elbakian, T. Chen, S. Taroian, C. A. Miller, Eugenio Nappi, S. I. Manaenkov, A. Nagaitsev, K. Oganessyan, A. Rostomyan, Salvatore Frullani, A. Funel, A. R. Reolon, A. Avetissian, G. van der Steenhoven, P. F. Dalpiaz, A. Borysenko, G. Gapienko, K. P. Schüler, I.A. Savin, Andreas Schäfer, E. De Sanctis, T. Michler, Franco Garibaldi, C. Shearer, B. Seitz, B. Maiheu, E. Avetissian, D. Balin, Nicola Bianchi, N. Akopov, O. Mikloukho, U. Elschenbroich, P. B. van der Nat, Y. J. Mao, P. Kravchenko, V. A. Gapienko, P. Di Nezza, P. Liebing, F. Masoli, J. G. Rubin, A. Laziev, H. C. Chiang, Song-Ming Wang, Y. X. Ye, Alessandra Fantoni, M. Hoek, B. Tchuiko, M. Kopytin, T. Keri, Wouter Deconinck, V. Mexner, Hidekazu Tanaka, K. Garrow, V. A. Kozlov, P. Zupranski, L. Lagamba, Z. Akopov, N. Meyners, J. Lu, G. Rosner, S. Yen, Ralf Kaiser, A. Airapetian, E. Steffens, F. Stinzing, G. Gavrilov, Xian Chen, J. Volmer, A. Ivanilov, L. Felawka, M. Amarian, X. R. Lu, M. Contalbrigo, G. P. Capitani, Martin Raithel, E. C. Aschenauer, G. Schnell, V. Shutov, I. Sanjiev, Naomi C R Makins, M. Hartig, A. Reischl, G. Ciullo, L. Rubacek, O. Grebeniouk, L. A. Linden-Levy, Y. Holler, L. Lapikás, J. Stewart, W.H.A. Hesselink, Valeria Muccifora, S. Lu, Adel Terkulov, Hasko Stenzel, M. Capiluppi, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: HERMES experiment, Nuclear and High Energy Physics, Particle physics, Lambda baryon, Lambda, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, Positron, 13.88.+e, 0103 physical sciences, ddc:530, 13.60.−r, 13.60.Rj, SDG 7 - Affordable and Clean Energy, 010306 general physics, Physics, 010308 nuclear & particles physics, Scattering, Hyperon, HERA, Deep inelastic scattering, Physics::Accelerator Physics, High Energy Physics::Experiment
Abstract: The transfer of polarization from a high-energy positron to a {lambda}{sup 0} hyperon produced in semiinclusive deep-inelastic scattering has been measured. The data have been obtained by the HERMES experiment at DESY using the 27.6 GeV longitudinally polarized positron beam of the HERA collider and unpolarized gas targets internal to the positron (electron) storage ring. The longitudinal spin-transfer coefficient is found to be D{sub LL{sup '}}{sup {lambda}}=0.11{+-}0.10(stat){+-}0.03(syst) at an average fractional energy carried by the {lambda}{sup 0} hyperon =0.45. The dependence of D{sub LL{sup '}}{sup {lambda}} on both the fractional energy z and the fractional longitudinal momentum x{sub F} is presented.
Published: 2006

10. Measurement of the tensor structure function b1 of the deuteron

Author: M. Vogt, H. Ohsuga, G. Gapienko, M. C. Simani, A. Rostomyan, A. R. Reolon, A. Avetissian, A. Tkabladze, B. D. Fox, G. Schnell, P. E. Reimer, M. Henoch, K. Oganessyan, Hidekazu Tanaka, H. E. Jackson, V. G. Krivokhijine, Gharibyan, T. A. Shibata, R.O. Avakian, E. Devitsin, W. Augustyniak, Erika Garutti, M. Stancari, U. Stosslein, L. Lagamba, Z. Akopov, J. Seele, S. Bernreuther, Shutov, Korotkov, A. Brull, B. Seitz, B. Hommez, J. Wilbert, Arne Vandenbroucke, Riccardo Fabbri, Di Nezza P, Muccifora, Michael Tytgat, M. Demey, Gapienko, I. M. Gregor, Alessandra Fantoni, M. Hoek, Y. Holler, S. Taroian, G. Graw, A. Andrus, W.-D. Nowak, Klaus Rith, D. Heesbeen, Mexner, G. Iarygin, B. Tchuiko, M. Kopytin, M. Negodaev, A. Nass, P. Bailey, U. Elschenbroich, H. Marukyan, A. Airapetian, A. Kisselev, L. Felawka, M. Amarian, A. Borissov, De Leo R, G. P. Capitani, M. Bouwhuis, L. G. Greeniaus, F. Stinzing, K. Hafidi, A. Laziev, H. Böttcher, B. Maiheu, C. Weiskopf, D. Reggiani, A. Jgoun, I.A. Savin, A. Hillenbrand, A. Fechtchenko, Y. X. Ye, P. Zupranski, P. Lenisa, A. Trzcinski, J. Dreschler, A. Elalaoui-Moulay, Frank Ellinghaus, B. Marianski, J. Volmer, A. Ivanilov, P. F. Dalpiaz, E. R. Kinney, N. Meyners, P. Tait, G. Rosner, V. V. Ammosov, F. Garibaldi, K. P. Schüler, De Sanctis E, K. Garrow, Y. Salomatin, H. P. Blok, E. Avetissian, B. Zihlmann, D. Balin, Nicola Bianchi, Y. Naryshkin, O. Mikloukho, Ralf Hertenberger, Wolfgang Lorenzon, J. G. Rubin, Hasko Stenzel, A. Reischl, B. Q. Ma, H. C. Chiang, M. Ehrenfried, G. Ciullo, Christian Schill, Bryzgalov, Houbing Lu, Eugenio Nappi, S. Potashov, L. Rubacek, D. H. Potterveld, Y. J. Mao, R. Seidl, M. Contalbrigo, Manuella Vincter, Martin Raithel, E. C. Aschenauer, De Nardo L, van der Steenhoven G, S. Belostotski, Kozlov, M. Hartig, I. Sanjiev, Naomi C R Makins, J. Stewart, S. Frullani, O. Grebeniouk, C. Riedl, P. Liebing, J. Lu, M. Beckmann, S. Yen, C. A. Miller, Ralf Kaiser, E. Steffens, G. Gavrilov, Vikhrov, Baturin, B. Krauss, L. A. Linden-Levy, N. Pickert, Dirk Ryckbosch, van der Nat Pb, S. Lu, M. Statera, Adel Terkulov, Andrey V. Izotov, D. Gaskell, L. Lapikás, Jeffrey Brack, Katerina Lipka, C. Vogel, G. Elbakian, J. J. M. Steijger, Michael Düren, Y. Miyachi, J. Wendland, D. Hasch, K. Sinram, Zhenyu Ye, C. Shearer, T. Chen, A. Nagaitsev, Michel Vetterli, N. Akopov, F. Masoli, Rezo Shanidze, Andreas Schäfer, W.H.A. Hesselink, A. Borysenko, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: HERMES experiment, Particle physics, media_common.quotation_subject, FOS: Physical sciences, General Physics and Astronomy, Spin structure, Inelastic scattering, Asymmetry, High Energy Physics - Experiment, 14.65.−q, Nuclear physics, High Energy Physics - Experiment (hep-ex), 13.88.+e, SDG 7 - Affordable and Clean Energy, Nuclear Experiment, media_common, Physics, 13.60.−r, 14.20.Dh, Scattering, Momentum transfer, HERA, Deep inelastic scattering, High Energy Physics::Experiment
Abstract: The \Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of \Hera. The use of a tensor polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry $\At$ and the tensor structure function $\bd$ for average values of the Bj��rken variable $0.01<< x>
Published: 2005

11. Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target

Author: P. Zupranski, P. Lenisa, L. Felawka, M. Amarian, Houbing Lu, A. Trzcinski, L. Lagamba, P. Di Nezza, C. Shearer, B. Seitz, E. Nappi, V. Muccifora, F. Masoli, S. Belostotski, G. Iarygin, V. Bryzgalov, A. Funel, G. van der Steenhoven, U. Elschenbroich, W.H.A. Hesselink, A. Borysenko, P. Bailey, G. Schnell, F. Garibaldi, N. Meyners, G. Rosner, Y. Salomatin, P. B. van der Nat, A. R. Reolon, Wouter Deconinck, H. Marukyan, Tsutomu Kobayashi, Andrey V. Izotov, J. Volmer, D. Hasch, P. E. Reimer, Hasko Stenzel, T. Chen, K. Hafidi, M. Negodaev, Z. Akopov, C. A. Miller, W. Augustyniak, M. Diefenthaler, A. Ivanilov, M. Contalbrigo, Martin Raithel, V. Mexner, S. Lu, G. Gapienko, Adel Terkulov, A. Fantoni, T. A. Shibata, Hidekazu Tanaka, E. C. Aschenauer, V. Shutov, V. A. Gapienko, R.O. Avakian, B. Q. Ma, I. Sanjiev, E. De Sanctis, T. Michler, B. Krauss, A. Nagaitsev, V. Gharibyan, A. Reischl, Dirk Ryckbosch, N. Bianchi, Naomi C R Makins, E. Devitsin, A. Kisselev, A. Osborne, T. Keri, D. Reggiani, M. Ehrenfried, H. E. Jackson, K. Garrow, V. G. Krivokhijine, A. Airapetian, V. A. Korotkov, J. Seele, J. Dreschler, R. De Leo, M. Demey, A. Hillenbrand, S. Frullani, A. Laziev, J. Lu, S. Yen, I. M. Gregor, F. Stinzing, L. Rubacek, A. Andrus, Michael Tytgat, Y. Holler, N. Pickert, Song-Ming Wang, N. Akopov, Ralf Kaiser, A. Elalaoui-Moulay, Frank Ellinghaus, S. Taroian, Y. X. Ye, G.P. Capitani, E. R. Kinney, E. Steffens, Y. J. Mao, H. Ohsuga, G. Elbakian, M. Hoek, Y. Naryshkin, G. Gavrilov, J. Stewart, B. Tchuiko, M. Kopytin, A. Rostomyan, A. Brüll, V. Vikhrov, A. Jgoun, Manuella Vincter, A. Avetissian, M. Statera, Y. Van Haarlem, C. Riedl, C. Vogel, Morgan Murray, R. Seidl, M. Bouwhuis, H. Böttcher, B. Maiheu, P. Tait, G. Ciullo, K. Sinram, L. De Nardo, Zhenyu Ye, B. Zihlmann, L. A. Linden-Levy, Y. Miyachi, J. Wendland, W. Sommer, D. H. Potterveld, L. Lapikás, M. Hartig, M. Capiluppi, P. Liebing, K. P. Schüler, B. Hommez, P.F. Dalpiaz, J. J. M. Steijger, Michael Düren, M. Stancari, D. Balin, O. Mikloukho, E. Avetissian, J. G. Rubin, A. Borissov, M. Beckmann, Klaus Rith, B. Marianski, C. Hadjidakis, I.A. Savin, Andreas Schäfer, W.-D. Nowak, Arne Vandenbroucke, Riccardo Fabbri, Alessandro Bacchetta, H. P. Blok, Wolfgang Lorenzon, Ivana Hristova, K. Oganessyan, V. Kozlov, O. Grebeniouk, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education
Subjects: Quark, Nuclear and High Energy Physics, Particle physics, Proton, Meson, Nuclear Theory, FOS: Physical sciences, Inelastic scattering, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, 13.60.-r, 13.88.+e, 14.20.Dh, 14.65.-q, 0103 physical sciences, SDG 14 - Life Below Water, 010306 general physics, Nuclear Experiment, Spin-½, Physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Deep inelastic scattering, Physics::Accelerator Physics, High Energy Physics::Experiment
Abstract: Single-spin asymmetries in the semi-inclusive production of charged pions in deep-inelastic scattering from transversely and longitudinally polarized proton targets are combined to evaluate the subleading-twist contribution to the longitudinal case. This contribution is significantly positive for π + mesons and dominates the asymmetries on a longitudinally polarized target previously measured by Hermes . The subleading-twist contribution for π − mesons is found to be small.
Published: 2005

12. Search for an exoticS=−2,Q=−2baryon resonance at a mass near 1862 MeV in quasireal photoproduction

Author: Klaus Rith, A. Nagaitsev, A. Funel, C. Shearer, B. Seitz, B. Maiheu, G. van der Steenhoven, W. Augustyniak, A. Andrus, I.A. Savin, A. Borysenko, Andreas Schäfer, J. Seele, Morgan Murray, U. Elschenbroich, P. B. van der Nat, Salvatore Frullani, M. Negodaev, N. Akopov, P. Lenisa, A. Trzcinski, A. Hillenbrand, B. Krauss, P. E. Reimer, Wouter Deconinck, P. F. Dalpiaz, Alessandra Fantoni, M. Hoek, V. Mexner, V. A. Gapienko, V. A. Korotkov, B. Tchuiko, M. Kopytin, K. Sinram, L. De Nardo, Y. Van Haarlem, G. Iarygin, Zhenyu Ye, P. Bailey, M. Stancari, M. Beckmann, A. Elalaoui-Moulay, Frank Ellinghaus, E. R. Kinney, V. Gharibyan, K. Garrow, Y. J. Mao, R. Seidl, Tsutomu Kobayashi, H. Marukyan, M. Bouwhuis, H. Böttcher, Y. Naryshkin, B. Hommez, G. Gapienko, F. Masoli, V. A. Kozlov, Michael Tytgat, P. Tait, J. J. M. Steijger, Michael Düren, Houbing Lu, T. Keri, A. Borissov, S. Taroian, H. E. Jackson, Y. Salomatin, A. Laziev, G. Elbakian, K. Hafidi, S. Belostotski, V. G. Krivokhijine, V. Bryzgalov, A. Osborne, B. Q. Ma, M. Diefenthaler, B. Zihlmann, M. Ehrenfried, Y. X. Ye, S. Wang, T. A. Shibata, Eugenio Nappi, R.O. Avakian, Cynthia Marie Hadjidakis, Y. Miyachi, O. Grebeniouk, C. Riedl, R. De Leo, J. Wendland, W. Sommer, D. Hasch, E. Devitsin, D. H. Potterveld, A. Kisselev, D. Reggiani, L. Felawka, M. Amarian, Dirk Ryckbosch, P. Zupranski, J. Drechsler, A. Jgoun, G. P. Capitani, H. P. Blok, C. Vogel, G. Schnell, H. Ohsuga, Wolfgang Lorenzon, L. Lagamba, Z. Akopov, Ivana Hristova, V. Vikhrov, A. Rostomyan, A. R. Reolon, A. Avetissian, Manuella Vincter, N. Meyners, K. Oganessyan, G. Rosner, P. Di Nezza, Hidekazu Tanaka, P. Liebing, A. Airapetian, W.-D. Nowak, K. P. Schüler, E. De Sanctis, T. Michler, Franco Garibaldi, F. Stinzing, E. Avetissian, D. Balin, Nicola Bianchi, O. Mikloukho, J. G. Rubin, M. Statera, B. Marianski, Hasko Stenzel, M. Contalbrigo, M. Capiluppi, Andrey V. Izotov, Martin Raithel, E. C. Aschenauer, Arne Vandenbroucke, V. Shutov, Riccardo Fabbri, I. Sanjiev, S. Lu, Naomi C R Makins, Adel Terkulov, M. Hartig, A. Reischl, N. Pickert, T. Chen, F. Giordano, W.H.A. Hesselink, M. Demey, G. Ciullo, J. Lu, S. Yen, I. M. Gregor, C. A. Miller, Ralf Kaiser, Valeria Muccifora, E. Steffens, L. A. Linden-Levy, G. Gavrilov, L. Lapikás, J. Volmer, A. Ivanilov, L. Rubacek, Y. Holler, J. Stewart, and A. Brüll
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Resonance, Lambda baryon, 01 natural sciences, Baryon, Particle decay, Exotic baryon, 0103 physical sciences, Mass spectrum, Invariant mass, Atomic physics, 010306 general physics
Abstract: A search for an exotic baryon resonance with $S=\ensuremath{-}2$, $Q=\ensuremath{-}2$ has been performed in quasireal photoproduction on a deuterium target through the decay channel ${\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\Lambda}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$. No evidence for a previously reported ${\ensuremath{\Xi}}^{--}(1860)$ resonance is found in the ${\ensuremath{\Xi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$ invariant mass spectrum. An upper limit for the photoproduction cross section of 2.1 nb is found at the 90% confidence level. The photoproduction cross section for the ${\ensuremath{\Xi}}^{0}(1530)$ is found to be between 9 and 24 nb.
Published: 2005

13. Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

Author: P. Zupranski, N. Meyners, G. Rosner, A. Airapetian, A. Borissov, Hidekazu Tanaka, A. Nagaitsev, A. Tkabladze, M. Negodaev, M. Contalbrigo, B. Hommez, Salvatore Frullani, P. E. Reimer, R. Seidl, C. Shearer, V. A. Korotkov, M. Bouwhuis, Martin Raithel, E. C. Aschenauer, V. Shutov, A. Hillenbrand, G. Graw, M. Henoch, V. A. Kozlov, I. Sanjiev, H. Ohsuga, Michel Vetterli, B. D. Fox, B. Zihlmann, H. C. Chiang, S. Belostotski, J. Volmer, H. P. Blok, Erika Garutti, H. Böttcher, A. Ivanilov, B. Seitz, M. Statera, V. A. Gapienko, G. Orlandi, V. Bryzgalov, Wolfgang Lorenzon, Naomi C R Makins, G. Schnell, P. F. Dalpiaz, M. Stancari, D. Gaskell, N. Akopov, K. Königsmann, V. Baturin, U. Elschenbroich, L. Felawka, M. Amarian, A. Fechtchenko, Ralf Hertenberger, E. De Sanctis, V. Gharibyan, Franco Garibaldi, G. Iarygin, G. Elbakian, K. P. Schüler, Y. Holler, S. Bernreuther, Andrey V. Izotov, A. Elalaoui-Moulay, Frank Ellinghaus, P. B. van der Nat, E. R. Kinney, P. Bailey, P. Tait, G. P. Capitani, A. Schwind, Dirk Ryckbosch, Valeria Muccifora, W.H.A. Hesselink, H. Marukyan, E. Avetissian, Nicola Bianchi, O. Mikloukho, A. Rostomyan, A. R. Reolon, Y. Naryshkin, J. Franz, Michael Tytgat, S. Potashov, O. Grebeniouk, H. Zohrabian, U. Stosslein, L. Lagamba, M. C. Simani, A. Avetissian, Z. Akopov, F. Masoli, J. Visser, M. Vogt, V. Vikhrov, Manuella Vincter, J. Lu, S. Taroian, S. Yen, G. V. Ybeles Smit, C. A. Miller, L. G. Greeniaus, C. Weiskopf, A. Andrus, Katerina Lipka, H. E. Jackson, Ralf Kaiser, J. Seele, B. Krauss, V. G. Krivokhijine, P. Di Nezza, Alessandra Fantoni, J. Ely, A. Reischl, Y. Miyachi, L. Rubacek, M. Hoek, A. Jgoun, C. Scarlett, K. Hafidi, E. Steffens, P. Liebing, C. Baumgarten, G. Gapienko, G. Gavrilov, P. Lenisa, G. Ciullo, C. Vogel, C. Riedl, R. Fabbri, T. A. Shibata, K. Oganessyan, J. Wendland, Christian Schill, R.O. Avakian, A. Trzcinski, Adel Terkulov, B. Tchuiko, M. Kopytin, D. Hasch, A. Nass, D. Reggiani, V. Mexner, L. Lapikás, E. Devitsin, J. Stewart, V. V. Ammosov, A. Brüll, J. Wilbert, Y. Gärber, D. H. Potterveld, Y. Salomatin, Arne Vandenbroucke, R. Shanidze, M. Hartig, A. Laziev, W. Augustyniak, N. Pickert, M. Ehrenfried, K. Garrow, R. De Leo, B. Marianski, Jeffrey Brack, W.-D. Nowak, Eugenio Nappi, A. Kisselev, B. Maiheu, M. Beckmann, K. Sinram, L. De Nardo, J. J. M. Steijger, Michael Düren, G. van der Steenhoven, T. Lindemann, Klaus Rith, D. Heesbeen, I.A. Savin, Andreas Schäfer, (Astro)-Particles Physics, Photo Conversion Materials, and Student Lab and Education
Subjects: Quark, Particle physics, Meson, High Energy Physics::Lattice, Nuclear Theory, Hadron, FOS: Physical sciences, General Physics and Astronomy, 13.60.–r, Inelastic scattering, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, 13.88.+e, Nuclear Experiment, 14.20.Dh, 14.65.–q, QC, Physics, High Energy Physics::Phenomenology, Quark model, Deep inelastic scattering, Baryon, High Energy Physics::Experiment
Abstract: Double-spin asymmetries of semi-inclusive cross sections for the production of identified pions and kaons have been measured in deep-inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with re-analyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data., Comment: 5 pages, 3 figures
Published: 2004

14. The HERMES Polarized Hydrogen and Deuterium Gas Target in the HERA Electron Storage Ring

Author: G. Graw, Y. Salomatin, V. A. Gapienko, N. Bianchi, V. A. Korotkov, K. Sinram, L. De Nardo, M. Ehrenfried, R. De Leo, B. Hommez, W. Haeberli, Y. Van Haarlem, R. Seidl, J. G. Rubin, L. Lapikás, M. Bouwhuis, H. Böttcher, L. Rubacek, J. Seele, P. Tait, Michael Tytgat, E. Avetissian, K. Garrow, H. Ohsuga, Dirk Ryckbosch, A. Airapetian, Klaus Rith, G. Elbakian, W. Augustyniak, S. Lu, D. Heesbeen, B. Zihlmann, L. A. Linden-Levy, S. Taroian, Adel Terkulov, H. E. Jackson, V. G. Krivokhijine, H. P. Blok, A. Borissov, Y. Miyachi, J. Wendland, C. Baumgarten, W. Sommer, A. Reischl, F. Stinzing, Wolfgang Lorenzon, B. Maiheu, A. Rostomyan, A. Avetissian, D. H. Potterveld, Z. Akopov, G. Iarygin, J. Stewart, A. Brüll, C. Hadjidakis, Bo-Qiang Ma, R. Mussa, Ivana Hristova, G. Schnell, C. A. Miller, P. Bailey, J. Wilbert, P. E. Reimer, Rezo Shanidze, M. Henoch, G. Gapienko, Arne Vandenbroucke, G. van der Steenhoven, V. Vikhrov, Manuella Vincter, A. Nagaitsev, Michel Vetterli, A. Fantoni, E. De Sanctis, V. Kozlov, A. Laziev, Riccardo Fabbri, M. Statera, Hidekazu Tanaka, D. Reggiani, W.H.A. Hesselink, A. Borysenko, G. Ciullo, K. P. Schüler, P.F. Dalpiaz, N. Koch, B. Braun, T. Kobayashi, N. Akopov, O. Grebeniouk, Z. Ye, Y. Mao, P. Lenisa, V. Gharibyan, J. J. M. Steijger, Michael Düren, A. Trzcinski, J. Volmer, M. Stancari, T. Wise, C. Schill, A. Jgoun, Y. X. Ye, A. Ivanilov, A. Fechtchenko, C. Vogel, D. Balin, O. Mikloukho, M. Beckmann, W.-D. Nowak, A. R. Reolon, C. Shearer, Hasko Stenzel, C. Riedl, L. Felawka, B. Seitz, M. Amarian, E. Nappi, K. Hafidi, V. Mexner, I.A. Savin, L. Lagamba, V. Muccifora, U. Elschenbroich, M. Demey, P. Zupranski, P. Di Nezza, H. Kolster, Y. Holler, K. Oganessyan, P. B. van der Nat, I. M. Gregor, N. Meyners, G. Rosner, A. Osborne, Ralf Hertenberger, T. A. Shibata, M. Hartig, G.P. Capitani, Andrey V. Izotov, R.O. Avakian, M. Hoek, D. Hasch, B. Marianski, G.R. Court, G. V. Ybeles Smit, M. Capiluppi, B. Tchuiko, M. Kopytin, A. Nass, S. Frullani, P. Liebing, N. Pickert, E. Devitsin, J. Lu, A. Kisselev, S. Yen, Ralf Kaiser, E. Steffens, A. Hillenbrand, G. Gavrilov, M. Contalbrigo, Martin Raithel, T. Chen, E. C. Aschenauer, V. Shutov, I. Sanjiev, Naomi C R Makins, H. Marukyan, Houbing Lu, S. Belostotski, A. Andrus, V. Bryzgalov, M. Negodaev, F. Garibaldi, Sihui Wang, A. Elalaoui-Moulay, Frank Ellinghaus, E. R. Kinney, Y. Naryshkin, B. Krauss, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: 29.25.Pj, Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Hydrogen, Atomic Physics (physics.atom-ph), chemistry.chemical_element, FOS: Physical sciences, 07.60.F, Electron, 01 natural sciences, Physics - Atomic Physics, NO, 07.77, 29.25.-t, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Physics::Atomic Physics, 010306 general physics, Instrumentation, Physics, 67.65, 010308 nuclear & particles physics, DESY, HERA, Instrumentation and Detectors (physics.ins-det), Polarization (waves), 29.25.P, chemistry, Deuterium, Cathode ray, Atomic physics, Nucleon
Abstract: The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA electron ring. Atoms diffusing from the center of the storage cell into a side tube are analyzed to determine the atomic fraction and the atomic polarizations. The atoms have a nuclear polarization, the axis of which is defined by an external magnetic holding field. The holding field was longitudinal during 1996-2000, and was changed to transverse in 2001. The design of the target is described, the method for analyzing the target polarization is outlined, and the performance of the target in the various running periods is presented. © 2004 Elsevier B.V. All rights reserved.
Published: 2004
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15. Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction

Author: J. Stewart, A. Brüll, Ralf Hertenberger, W.H.A. Hesselink, J. Lu, S. Yen, K. Garrow, Y. Salomatin, Z. Ye, L. A. Linden-Levy, C. A. Miller, B. Hommez, Wouter Deconinck, C. Shearer, Ralf Kaiser, P. Zupranski, A. Elalaoui-Moulay, Frank Ellinghaus, E. Steffens, A. Jgoun, Ingrid-Maria Gregor, H. P. Blok, W. Augustyniak, G. Ciullo, E. R. Kinney, G. Gavrilov, U. Elschenbroich, B. Marianski, Wolfgang Lorenzon, J. Ely, V. Mexner, N. Meyners, G. Rosner, M. Ehrenfried, R. De Leo, A. Fantoni, A. Tkabladze, P. B. van der Nat, H. Y. Lu, M. Contalbrigo, B. D. Fox, Y. Naryshkin, Dirk Ryckbosch, B. Zihlmann, K. P. Schüler, Jeffrey Brack, Katerina Lipka, Martin Raithel, W.-D. Nowak, C. Riedl, T. Chen, E. C. Aschenauer, G. Schnell, P.F. Dalpiaz, V. Shutov, M. Vogt, I. Sanjiev, K. Hafidi, M. Statera, Hasko Stenzel, A. Kisselev, H. E. Jackson, Michael Tytgat, Naomi C R Makins, F. Masoli, E. Nappi, A. Nagaitsev, D. Gaskell, A. Airapetian, D. Balin, O. Mikloukho, A. Hillenbrand, G. Iarygin, S. Belostotski, E. De Sanctis, V. Gharibyan, V. Bryzgalov, V. G. Krivokhijine, S. Potashov, K. Oganessyan, J. Wilbert, H. Zohrabian, F. Garibaldi, A. Fechtchenko, Michel Vetterli, R. Seidl, A. Borissov, Arne Vandenbroucke, G. Graw, S. Taroian, M. Bouwhuis, H. Böttcher, P. Lenisa, A. R. Reolon, A. Laziev, Riccardo Fabbri, V. A. Gapienko, C. Vogel, A. Andrus, A. Trzcinski, D. Reggiani, F. Stinzing, N. Akopov, N. Bianchi, V. V. Ammosov, H. Marukyan, R. Shanidze, Y. X. Ye, P. E. Reimer, P. Tait, M. Negodaev, S. Frullani, X. R. Lu, Bo-Qiang Ma, V. Kozlov, L. Lapikás, B. Krauss, V. Muccifora, P. Liebing, Erika Garutti, U. Stosslein, M. Hoek, M. Henoch, T. A. Shibata, E. Avetissian, V. A. Korotkov, J. G. Rubin, N. Pickert, R.O. Avakian, Xun Chen, J. Seele, S. Bernreuther, O. Grebeniouk, Z. Akopov, E. Devitsin, B. Tchuiko, M. Kopytin, S. Lu, Hidekazu Tanaka, A. Nass, Adel Terkulov, V. Baturin, V. Vikhrov, Manuella Vincter, H. C. Chiang, G. Elbakian, P. Bailey, Andrey V. Izotov, G.P. Capitani, D. Hasch, B. Maiheu, Y. Mao, G. V. Ybeles Smit, L. G. Greeniaus, B. Seitz, C. Weiskopf, L. Felawka, M. Amarian, L. Lagamba, P. Di Nezza, G. Gapienko, M. C. Simani, Y. Miyachi, J. Wendland, D. H. Potterveld, H. Ohsuga, A. Rostomyan, A. Avetissian, K. Sinram, L. De Nardo, J. J. M. Steijger, Michael Düren, M. Stancari, A. Reischl, C. Schill, M. Beckmann, J. Volmer, A. Ivanilov, Y. Holler, G. van der Steenhoven, M. Hartig, A. Borysenko, W. Yu, I.A. Savin, Andreas Schäfer, Klaus Rith, D. Heesbeen, and L. Rubacek
Subjects: Nuclear and High Energy Physics, Particle physics, Nuclear Theory, FOS: Physical sciences, 01 natural sciences, NO, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, Invariant mass, 12.39.Mk, 13.60.-r, 13.60.Rj, 14.20.-c, 010306 general physics, Nuclear Experiment, Physics, Isovector, 010308 nuclear & particles physics, State (functional analysis), Pentaquark, Baryon, Deuterium, Exotic baryon, Mass spectrum, High Energy Physics::Experiment
Abstract: Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel p K^0_S --> p pi^+ pi^-. A peak is observed in the p K^0_S invariant mass spectrum at 1528 +/- 2.6 (stat) +/-2.1 (syst) MeV. Depending on the background model,the naive statistical significance of the peak is 4--6 standard deviations and its width may be somewhat larger than the experimental resolution of sigma=4.3 -- 6.2 MeV. This state may be interpreted as the predicted S=+1 exotic Theta^{+}(uuddbar(s)) pentaquark baryon. No signal for an hypothetical Theta^{++} baryon was observed in the pK^+ invariant mass distribution. The absence of such a signal indicates that an isotensor Theta is excluded and an isovector Theta is unlikely., 8 pages, 4 figures
Published: 2003

16. Q2Dependence of Nuclear Transparency for Exclusiveρ0Production

Author: I. Brunn, A. Kisselev, J. Wilbert, A. Nagaitsev, U. Stosslein, L. Lagamba, Z. Akopov, V. A. Korotkov, Michel Vetterli, A. Laziev, V. Gapienko, P. E. Reimer, M. Henoch, B. D. Fox, B. Zihlmann, Y. Miyachi, M. Stancari, T. Wise, J. Wendland, W. Augustyniak, G. van der Steenhoven, N. Akopov, G. Schnell, D. Hasch, K. Königsmann, V. Baturin, B. Hommez, M. Beckmann, D. H. Potterveld, H. P. Blok, Alessandra Fantoni, S. Tessarin, S. Yoneyama, T. Lindemann, K. Hafidi, H. Kolster, H. Ohsuga, G. Elbakian, G. Graw, Wolfgang Lorenzon, S. Bernreuther, A. Tkabladze, A. Elalaoui-Moulay, Frank Ellinghaus, Dirk Ryckbosch, R. Fabbri, B. Tchuiko, M. Kopytin, T. A. Shibata, A. Nass, S. Podiatchev, A. Rostomyan, R.O. Avakian, E. R. Kinney, A. R. Reolon, A. Avetissian, A. Jgoun, B. Seitz, A. Schwind, P. Lenisa, J. Seibert, K. Sinram, E. Devitsin, L. De Nardo, A. Trzcinski, G. Gapienko, O. Grebeniouk, P. B. van der Nat, D. Reggiani, M. Vogt, Y. Naryshkin, V. Gharibyan, V. V. Ammosov, K. Oganessyan, M. Ehrenfried, A. Hillenbrand, E. De Sanctis, V. Vikhrov, Manuella Vincter, Franco Garibaldi, R. De Leo, V. A. Kozlov, Klaus Rith, D. Heesbeen, M. Bouwhuis, J. J. M. Steijger, Michael Düren, L. G. Greeniaus, C. Weiskopf, H. Böttcher, H. E. Jackson, S. Belostotski, V. G. Krivokhijine, Eugenio Nappi, Erika Garutti, C. Baumgarten, A. Andrus, G. Iarygin, L. Felawka, I.A. Savin, B. Krauss, G. P. Capitani, H. Marukyan, R. Van de Vyver, C. Scarlett, G.R. Court, J. Franz, Andreas Schäfer, A. Terkulov, K. Negodaeva, M. Amarian, M. Hartig, S. Potashov, H. Zohrabian, Hidekazu Tanaka, U. Elschenbroich, A. Airapetian, P. Bailey, G. M. Urciuoli, P. Di Nezza, J. Stewart, P. Liebing, A. Brüll, Ralf Hertenberger, W.H.A. Hesselink, P. Zupranski, H. C. Chiang, N. Meyners, G. Rosner, L. Lapikás, K. P. Schüler, A. Borissov, E. Avetissian, Nicola Bianchi, O. Mikloukho, A. Reischl, W. Haeberli, G. Ciullo, Christian Schill, Salvatore Frullani, Valeria Muccifora, P. F. Dalpiaz, Y. Holler, Jeffrey Brack, M. C. Simani, J. Volmer, A. Fechtchenko, Michael Tytgat, S. Taroian, Y. Gärber, E. Thomas, R. Shanidze, M. Contalbrigo, Martin Raithel, E. C. Aschenauer, V. Shutov, M. Statera, I. Sanjiev, Andrey V. Izotov, G. Orlandi, Naomi C R Makins, C. A. Miller, J. Ely, D. Gaskell, F. Menden, S. Yen, Ralf Kaiser, E. Steffens, G. Gavrilov, F. Masoli, J. Visser, V. Mexner, and W.-D. Nowak
Subjects: HERMES experiment, Physics, Nuclear reaction, Particle physics, Meson, Nuclear Theory, Hadron, General Physics and Astronomy, Virtual particle, Coherence length, Nuclear physics, Nuclear transparency, High Energy Physics::Experiment, Nuclear Experiment, Nucleon
Abstract: Exclusive coherent and incoherent electroproduction of the rho(0) meson from H-1 and N-14 targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q(2)). The ratio of N-14 to H-1 cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q(2) is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.
Published: 2003

17. Quark fragmentation to π±, π0, K±, p and p_bar in the nuclear environment

Author: R. Fabbri, Katerina Lipka, A. Fechtchenko, T. A. Shibata, M. Statera, K. P. Schüler, R.O. Avakian, E. Nappi, Dirk Ryckbosch, C. Shearer, C. Vogel, B. Seitz, E. Devitsin, O. Mikloukho, A. R. Reolon, J. Seele, S. Bernreuther, J. Wilbert, L. Lapikás, U. Elschenbroich, P. B. van der Nat, Adel Terkulov, Arne Vandenbroucke, H. E. Jackson, V. G. Krivokhijine, G. Gapienko, S. Belostotski, V. Bryzgalov, Y. Salomatin, W. Augustyniak, A. Tkabladze, F. Garibaldi, C. Baumgarten, Ralf Hertenberger, E. Avetissian, H. C. Chiang, B. D. Fox, Y. Holler, V. A. Korotkov, K. Sinram, L. De Nardo, G. Schnell, M. C. Simani, M. Stancari, M. Contalbrigo, V. Vikhrov, W.H.A. Hesselink, S. Potashov, P. E. Reimer, H. Zohrabian, Martin Raithel, Manuella Vincter, E. C. Aschenauer, V. Shutov, M. Henoch, Jeffrey Brack, H. Tanaka, K. Königsmann, B. Krauss, M. Hoek, V. Baturin, I. Sanjiev, A. Airapetian, Hasko Stenzel, C. Scarlett, V. Gharibyan, G. Graw, M. Ehrenfried, Naomi C R Makins, D. Gaskell, R. De Leo, P. Liebing, K. Hafidi, G. Elbakian, A. Borissov, L. Rubacek, M. Vogt, B. Tchuiko, M. Kopytin, J. Lu, A. Nass, B. Hommez, S. Yen, A. Elalaoui-Moulay, Frank Ellinghaus, E. R. Kinney, G. V. Ybeles Smit, R. Seidl, E. Garutti, A. Hillenbrand, V. Mexner, A. Schwind, Ralf Kaiser, Y. Naryshkin, B. Marianski, Andrey V. Izotov, E. De Sanctis, M. Bouwhuis, H. Ohsuga, H. Böttcher, E. Steffens, J. Stewart, A. Brüll, G. Gavrilov, D. Hasch, Y. Miyachi, J. Wendland, K. Oganessyan, A. Laziev, W.-D. Nowak, Michael Tytgat, A. Ivanilov, L. Felawka, V. Gapienko, B. Maiheu, P. Tait, D. H. Potterveld, M. Amarian, C. A. Miller, K. Garrow, J. Ely, A. Rostomyan, A. Avetissian, A. Kisselev, L. Lagamba, A. Fantoni, A. Reischl, S. Taroian, N. Bianchi, A. Nagaitsev, J. J. M. Steijger, Michael Düren, P. Di Nezza, G. Iarygin, Michel Vetterli, G. Ciullo, Christian Schill, H. Marukyan, J. Franz, B. Zihlmann, R. Shanidze, V. Kozlov, S. Frullani, N. Pickert, N. Akopov, O. Grebeniouk, P. F. Dalpiaz, G.P. Capitani, H. P. Blok, P. Zupranski, Wolfgang Lorenzon, V. V. Ammosov, J. Volmer, F. Masoli, N. Meyners, G. Rosner, U. Stosslein, Z. Akopov, G. van der Steenhoven, T. Lindemann, L. G. Greeniaus, C. Weiskopf, A. Borysenko, Klaus Rith, D. Heesbeen, I.A. Savin, Andreas Schäfer, P. Lenisa, A. Trzcinski, D. Reggiani, V. Muccifora, M. Hartig, M. Negodaev, P. Bailey, I. M. Gregor, A. Jgoun, C. Riedl, M. Beckmann, and A. Andrus
Subjects: HERMES experiment, Quark, Nuclear and High Energy Physics, Meson, Nuclear Theory, Hadron, chemistry.chemical_element, 13.87.Fh, 13.60.-r, 14.20.-c, 14.40.-n, 01 natural sciences, 7. Clean energy, Nuclear physics, 0103 physical sciences, Multiplicity (chemistry), Nuclear Experiment, 010306 general physics, Physics, 010308 nuclear & particles physics, Krypton, Baryon, Deuterium, chemistry, High Energy Physics::Experiment, Atomic physics
Abstract: The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi-inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium, nitrogen and krypton targets. The differential multiplicity for krypton relative to that of deuterium has been measured for the first time for various identified hadrons (π+, π−, π0, K+, K−, p and p ) as a function of the virtual photon energy ν, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared pt2. The multiplicity ratio is strongly reduced in the nuclear medium at low ν and high z, with significant differences among the various hadrons. The distribution of the hadron transverse momentum is broadened towards high pt2 in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei.
Published: 2003

18. Q2 dependence of nuclear transparency for exclusive rho0 production

Author: A, Airapetian, N, Akopov, Z, Akopov, M, Amarian, V V, Ammosov, A, Andrus, E C, Aschenauer, W, Augustyniak, R, Avakian, A, Avetissian, E, Avetissian, P, Bailey, V, Baturin, C, Baumgarten, M, Beckmann, S, Belostotski, S, Bernreuther, N, Bianchi, H P, Blok, H, Böttcher, A, Borissov, M, Bouwhuis, J, Brack, A, Brüll, I, Brunn, G P, Capitani, H C, Chiang, G, Ciullo, M, Contalbrigo, G R, Court, P F, Dalpiaz, R, De Leo, L, De Nardo, E, De Sanctis, E, Devitsin, P, Di Nezza, M, Düren, M, Ehrenfried, A, Elalaoui-Moulay, G, Elbakian, F, Ellinghaus, U, Elschenbroich, J, Ely, R, Fabbri, A, Fantoni, A, Fechtchenko, L, Felawka, B, Fox, J, Franz, S, Frullani, Y, Gärber, G, Gapienko, V, Gapienko, F, Garibaldi, E, Garutti, D, Gaskell, G, Gavrilov, V, Gharibyan, G, Graw, O, Grebeniouk, L G, Greeniaus, W, Haeberli, K, Hafidi, M, Hartig, D, Hasch, D, Heesbeen, M, Henoch, R, Hertenberger, W H A, Hesselink, A, Hillenbrand, Y, Holler, B, Hommez, G, Iarygin, A, Izotov, H E, Jackson, A, Jgoun, R, Kaiser, E, Kinney, A, Kisselev, K, Königsmann, H, Kolster, M, Kopytin, V, Korotkov, V, Kozlov, B, Krauss, V G, Krivokhijine, L, Lagamba, L, Lapikás, A, Laziev, P, Lenisa, P, Liebing, T, Lindemann, W, Lorenzon, N C R, Makins, H, Marukyan, F, Masoli, F, Menden, V, Mexner, N, Meyners, O, Mikloukho, C A, Miller, Y, Miyachi, V, Muccifora, A, Nagaitsev, E, Nappi, Y, Naryshkin, A, Nass, K, Negodaeva, W-D, Nowak, K, Oganessyan, H, Ohsuga, G, Orlandi, S, Podiatchev, S, Potashov, D H, Potterveld, M, Raithel, D, Reggiani, P, Reimer, A, Reischl, A R, Reolon, K, Rith, G, Rosner, A, Rostomyan, D, Ryckbosch, I, Sanjiev, I, Savin, C, Scarlett, A, Schäfer, C, Schill, G, Schnell, K P, Schüler, A, Schwind, J, Seibert, B, Seitz, R, Shanidze, T-A, Shibata, V, Shutov, M C, Simani, K, Sinram, M, Stancari, M, Statera, E, Steffens, J J M, Steijger, J, Stewart, U, Stösslein, H, Tanaka, S, Taroian, B, Tchuiko, A, Terkulov, S, Tessarin, E, Thomas, A, Tkabladze, A, Trzcinski, M, Tytgat, G M, Urciuoli, P, Van Der Nat, G, Van Der Steenhoven, R, Van De Vyver, M C, Vetterli, V, Vikhrov, M G, Vincter, J, Visser, M, Vogt, J, Volmer, C, Weiskopf, J, Wendland, J, Wilbert, T, Wise, S, Yen, S, Yoneyama, B, Zihlmann, H, Zohrabian, and P, Zupranski
Abstract: Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.
Published: 2002

19. Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$

Author: Michel Vetterli, N. Akopov, F. Menden, B. Hommez, Klaus Rith, D. Heesbeen, L. G. Greeniaus, E. De Sanctis, U. Stosslein, Franco Garibaldi, C. A. Miller, S. Yen, C. Weiskopf, L. Lagamba, A. Jgoun, B. D. Fox, B. Zihlmann, Z. Akopov, J. Ely, Ralf Kaiser, G. Schnell, A. Rostomyan, A. R. Reolon, A. Avetissian, G. M. Urciuoli, J. Stewart, E. Steffens, E. Kotik, A. Brüll, G. Hofman, W. Haeberli, G. Gavrilov, V. V. Ammosov, F. Masoli, J. Visser, F. Sato, A. Reischl, K. Negodaeva, A. Fechtchenko, G. S. Kyle, I.A. Savin, K. Sinram, H. J. Bulten, L. De Nardo, B. Tipton, K. P. Schüler, U. Elschenbroich, M. Amarian, R. Van de Vyver, G. Ciullo, H. P. Blok, S. Yoneyama, Evaristo Cisbani, Valeria Muccifora, V. Gharibyan, L. Felawka, G. Iarygin, Christian Schill, S. Brauksiepe, B. Krauss, E. Avetissian, Nicola Bianchi, O. Mikloukho, Wolfgang Lorenzon, S. Potashov, H. Zohrabian, C. Scarlett, P. Bailey, H. Marukyan, G. P. Capitani, G.R. Court, Axel Maas, Andreas Schäfer, Eugenio Nappi, J. Franz, Andrey V. Izotov, A. Airapetian, P. Kitching, G. van der Steenhoven, J. Wendland, Michael Tytgat, P.W. Green, D. H. Potterveld, M. Bouwhuis, H. Böttcher, P. Di Nezza, F.H. Heinsius, Frank Ellinghaus, S. Taroian, V. Mexner, T. Lindemann, E. R. Kinney, V. Rappoport, P. Liebing, T. Wise, V. A. Korotkov, A. Schwind, R. Shanidze, S. Podiatchev, F. Schmidt, Martin Raithel, R. J. Holt, Y. Naryshkin, M. Beckmann, J. F. J. van den Brand, E. C. Aschenauer, V. Shutov, O. Grebeniouk, M. Stancari, Salvatore Frullani, J. J. M. Steijger, I. Sanjiev, P. F. Dalpiaz, K. Königsmann, Michael Düren, G. Orlandi, Naomi C R Makins, V. Baturin, S. Tessarin, P. Lenisa, J. Seibert, V. A. Kozlov, B. W. Filippone, D. Reggiani, J. Volmer, G. Elbakian, S. Belostotski, S. Bernreuther, Adel Terkulov, Yasuhiro Sakemi, M. Ehrenfried, R. De Leo, Erika Garutti, Y. Holler, V. Vikhrov, M. C. Simani, Manuella Vincter, Y. Gärber, P.K.A. de Witt Huberts, M. Hartig, E. Thomas, H. Avakian, Ralf Hertenberger, W.H.A. Hesselink, A. Gute, Dirk Ryckbosch, Othmane Bouhali, P. E. Reimer, M. Henoch, K. Suetsugu, R. Fabbri, T. A. Shibata, R.O. Avakian, H. E. Jackson, V. G. Krivokhijine, E. Devitsin, C. Baumgarten, N. Meyners, A. Borissov, K. Hafidi, V. A. Gapienko, H. Kolster, Alessandra Fantoni, G. Graw, M. Kopytin, A. Nass, Peter Jung, B. Seitz, D. Hasch, A. Laziev, K. Oganessyan, J. Wilbert, W.-D. Nowak, I. Brunn, A. Kisselev, H. Fischer, Jeffrey Brack, A. Nagaitsev, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: Quark, Particle physics, media_common.quotation_subject, Hadron, Nuclear Theory, FOS: Physical sciences, General Physics and Astronomy, Inelastic scattering, 01 natural sciences, Asymmetry, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Q(2)-DEPENDENCE, 0103 physical sciences, Proton spin crisis, SCATTERING, 010306 general physics, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, SUM, CONSTRAINTS, Deep inelastic scattering, 3. Good health, Baryon, POLARIMETER, NEUTRON, High Energy Physics::Experiment, POLARIZED HYDROGEN, Nucleon, RESONANCES, BEHAVIOR
Abstract: Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry $A_1$. Longitudinally polarised positrons were scattered off a longitudinally polarised hydrogen target for values of $Q^2$ between 1.2 and 12 GeV$^2$ and values of $W^2$ between 1 and 4 GeV$^2$. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable $x$. This finding implies that the description of $A_1$ in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of $Q^2$ above 1.6 GeV$^2$., 5 pages, 1 eps figure, table added, new references added, in print in Phys. Rev. Lett
Published: 2002

20. Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

Author: M. Henoch, W.H.A. Hesselink, K. Suetsugu, V. Djordjadze, Y. Holler, M. C. Simani, P.K.A. de Witt Huberts, H. J. Bulten, G. Ciullo, Christian Schill, W. Haeberli, S. Brauksiepe, P. Chumney, D. Robinson, V. Vikhrov, A. Rostomyan, A. R. Reolon, A. Avetissian, W.-D. Nowak, N. Meyners, Manuella Vincter, S. Potashov, H. Zohrabian, Michael Tytgat, G. S. Kyle, B. Hommez, B. Seitz, Axel Maas, A. Gute, S. Taroian, Hiroaki Kobayashi, P. Bailey, T. Wise, L. Felawka, F. Schmidt, B. D. Fox, Salvatore Frullani, S. Belostotski, E. De Sanctis, H. E. Jackson, V. G. Krivokhijine, A. Schwind, P. Di Nezza, Franco Garibaldi, M. Beckmann, J. F. J. van den Brand, Jeffrey Brack, P. Liebing, P. F. Dalpiaz, I. Brunn, A. Kisselev, P.W. Green, C. Baumgarten, G. M. Urciuoli, R. Van de Vyver, Klaus Rith, G. P. Capitani, D. Hasch, A. Simon, Thomas O'Neill, K. P. Schüler, D. Heesbeen, F.H. Heinsius, Frank Ellinghaus, E. R. Kinney, K. Negodaeva, M. Amarian, N. Koch, J. Wendland, D. H. Potterveld, E. Kotik, B. R. Owen, Yasuhiro Sakemi, E. Avetissian, Nicola Bianchi, O. Mikloukho, Evaristo Cisbani, M. Ruh, Y. Naryshkin, G. Iarygin, Dirk Ryckbosch, J. Stewart, A. Brüll, A. Airapetian, A. Laziev, A. Borissov, G. Hofman, V. A. Kozlov, M. Hartig, A. Jgoun, M. Ehrenfried, J. van Hunen, H. Marukyan, R. De Leo, B. Krauss, J. Franz, B. Tipton, M. Bouwhuis, C. Scarlett, H. Böttcher, S. F. Pate, O. Grebeniouk, Erika Garutti, U. Stosslein, J. J. M. Steijger, P. Lenisa, J. Seibert, Alessandra Fantoni, L. G. Greeniaus, L. Lagamba, Z. Akopov, B. W. Filippone, Eugenio Nappi, F. Sato, C. Weiskopf, D. Reggiani, K. McIlhany, A. Nass, Peter Jung, K. Sinram, L. De Nardo, V. Gharibyan, I.A. Savin, S. Yoneyama, G.R. Court, Wolfgang Lorenzon, Andreas Schäfer, M. McAndrew, F. Meissner, G. van der Steenhoven, K. Oganessyan, A. Golendukhin, T. Lindemann, H. Fischer, J. Wilbert, V. A. Korotkov, G. Graw, H. Kolster, D. De Schepper, K. Königsmann, V. Baturin, G. Rakness, G. Elbakian, W. Brückner, S. Bernreuther, K. Hafidi, R. J. Holt, F. Masoli, J. Visser, T. A. Shibata, R.O. Avakian, A. Nagaitsev, Michel Vetterli, N. Akopov, E. Devitsin, R. P. Redwine, M. Düren, R. Mussa, V. Rappoport, S. Tessarin, Ross Milner, C. A. Miller, J. Ely, Adel Terkulov, Andrey V. Izotov, H. Avakian, Othmane Bouhali, Y. Gärber, Valeria Muccifora, E. Thomas, G. Schnell, J. Kanesaka, Martin Raithel, E. C. Aschenauer, V. Shutov, B. Bains, I. Sanjiev, Naomi C R Makins, O.V. Teryaev, F. Menden, S. Yen, Ralf Kaiser, E. Steffens, G. Gavrilov, A. Fechtchenko, P. Kitching, Ralf Hertenberger, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: Quark, Nuclear and High Energy Physics, Particle physics, transverse [polarization], media_common.quotation_subject, FRAGMENTATION FUNCTIONS, FOS: Physical sciences, ODD PARTON DISTRIBUTIONS, HERMES, NUCLEONS, transverse momentum dependence, Asymmetry, fragmentation function, energy dependence, x-dependence, High Energy Physics - Experiment, Nuclear physics, 27.5 GeV, High Energy Physics - Experiment (hep-ex), Pion, 13.88.+e, ddc:530, deep inelastic scattering [positron p], Nuclear Experiment, QC, media_common, Physics, 13.60.-r, longitudinal [polarization], electroproduction [pi0], Scattering, QUARK, polarization [quark], Deep inelastic scattering, Polarization (waves), Transverse plane, DESY HERA Stor, 13.87.Fh, 14.20.Dh, analyzing power, polarized target [p], High Energy Physics::Experiment, asymmetry [spin], Lepton, experimental results
Abstract: A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The analysing power in the sin(phi) moment of the cross section is 0.019 +/- 0.007(stat.) +/- 0.003(syst.). This result is compared to single-spin asymmetries for charged pion production measured in the same kinematic range. The pi^0 asymmetry is of the same size as the pi^+ asymmetry and shows a similar dependence on the relevant kinematic variables. The asymmetry is described by a phenomenological calculation based on a fragmentation function that represents sensitivity to the transverse polarization of the struck quark., Comment: 4 pages, 1 figure, replaced to correct eprint author field, 2nd replacement to correct figure; upper limit of model predictions are corrected. No correction to data or conclusions
Published: 2001

21. Single-spin azimuthal asymmetry in exclusive electroproduction of pi^+ mesons

Author: A. Airapetian, N. Akopov, Z. Akopov, M. Amarian, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, V. Baturin, C. Baumgarten, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H. Böttcher, A. Borissov, O. Bouhali, M. Bouwhuis, J. Brack, S. Brauksiepe, A. Brüll, I. Brunn, H.J. Bulten, G.P. Capitani, P. Chumney, E. Cisbani, G. Ciullo, G.R. Court, P.F. Dalpiaz, R. De Leo, L. De Nardo, E. De Sanctis, D. De Schepper, E. Devitsin, P.K.A. de Witt Huberts, P. Di Nezza, M. Düren, M. Ehrenfried, G. Elbakian, F. Ellinghaus, J. Ely, R. Fabbri, A. Fantoni, A. Fechtchenko, L. Felawka, B.W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, Y. Gärber, F. Garibaldi, E. Garutti, G. Gavrilov, V. Gharibyan, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, A. Gute, W. Haeberli, K. Hafidi, M. Hartig, D. Hasch, D. Heesbeen, F.H. Heinsius, M. Henoch, R. Hertenberger, W.H.A. Hesselink, G. Hofman, Y. Holler, R.J. Holt, B. Hommez, G. Iarygin, A. Izotov, H.E. Jackson, A. Jgoun, P. Jung, R. Kaiser, A. Kisselev, P. Kitching, K. Königsmann, H. Kolster, V. Korotkov, E. Kotik, V. Kozlov, B. Krauss, V.G. Krivokhijine, G. Kyle, L. Lagamba, A. Laziev, P. Lenisa, P. Liebing, T. Lindemann, W. Lorenzon, A. Maas, N.C.R. Makins, H. Marukyan, F. Masoli, K. McIlhany, F. Meissner, F. Menden, V. Mexner, N. Meyners, O. Mikloukho, R. Milner, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, K. Negodaeva, W.-D. Nowak, K. Oganessyan, T.G. O'Neill, B.R. Owen, S.F. Pate, S. Podiatchev, S. Potashov, D.H. Potterveld, M. Raithel, G. Rakness, V. Rappoport, R. Redwine, D. Reggiani, P. Reimer, A.R. Reolon, K. Rith, D. Robinson, A. Rostomyan, D. Ryckbosch, Y. Sakemi, I. Sanjiev, F. Sato, I. Savin, C. Scarlett, A. Schäfer, C. Schill, F. Schmidt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, B. Seitz, T.-A. Shibata, V. Shutov, M.C. Simani, A. Simon, K. Sinram, E. Steffens, J.J.M. Steijger, J. Stewart, U. Stösslein, K. Suetsugu, S. Taroian, A. Terkulov, S. Tessarin, E. Thomas, B. Tipton, M. Tytgat, G.M. Urciuoli, J.F.J. van den Brand, G. van der Steenhoven, R. van de Vyver, M.C. Vetterli, V. Vikhrov, M.G. Vincter, J. Visser, J. Volmer, C. Weiskopf, J. Wendland, J. Wilbert, T. Wise, S. Yen, S. Yoneyama, H. Zohrabian, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: Nuclear and High Energy Physics, Particle physics, Meson, media_common.quotation_subject, Virtual particle, FOS: Physical sciences, 01 natural sciences, Asymmetry, NO, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Positron, 13.88.+e, 0103 physical sciences, 13.60.-r, 13.60.Le, 13.85.Fb, 010306 general physics, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, Scattering, LEADING ORDER, Polarization (waves), Physics and Astronomy, Condensed Matter::Strongly Correlated Electrons, High Energy Physics::Experiment, Nucleon, Lepton
Abstract: A single-spin asymmetry in the distribution of exclusively produced pi^+ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the sin \phi moment of the polarization asymmetry of the cross section is measured to be -0.18 +/- 0.05 (stat.) +/- 0.02 (syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing x and increasing -t and vanish at t -> t_min (where x is the Bjorken scaling variable and t is the squared four-momentum transferred to the nucleon)., Comment: PLB accepted version, 6 pages, 4 figures, LaTex (revtex4), corrected typo
Published: 2001
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22. Measurement of the Beam-Spin Azimuthal Asymmetry associated with Deep Virtual Compton Scattering

Author: J. Wilbert, D. De Schepper, S. Potashov, H. Zohrabian, W.-D. Nowak, G. S. Kyle, J. Stewart, I. Brunn, A. Kisselev, H. Fischer, L. Felawka, G. Graw, V. A. Korotkov, P. Lenisa, J. Seibert, H. Kolster, K. McIlhany, I.A. Savin, K. Königsmann, V. Baturin, B. D. Fox, W. Haeberli, B. Seitz, Yasuhiro Sakemi, E. Thomas, G. Schnell, H. J. Bulten, G. Ciullo, K. Sinram, P. Di Nezza, L. De Nardo, G. M. Urciuoli, B. W. Filippone, D. Reggiani, G.R. Court, Andreas Schäfer, Christian Schill, G. Elbakian, W. Brückner, B. Hommez, S. Bernreuther, H. Avakian, Othmane Bouhali, K. Negodaeva, M. McAndrew, M. Amarian, G. P. Capitani, P. Liebing, S. Brauksiepe, R. Van de Vyver, R. J. Holt, Michael Tytgat, F. Masoli, J. Visser, Klaus Rith, D. Heesbeen, M. Ruh, N. Meyners, V. Gharibyan, P. Chumney, E. Kotik, Evaristo Cisbani, S. Taroian, U. Stosslein, Salvatore Frullani, A. Rostomyan, R. Fabbri, T. A. Shibata, L. Lagamba, M. Hartig, A. R. Reolon, R.O. Avakian, Z. Akopov, P. F. Dalpiaz, G. van der Steenhoven, A. Avetissian, A. Golendukhin, T. Lindemann, Andrey V. Izotov, A. Airapetian, G. Iarygin, O. Grebeniouk, E. Devitsin, Axel Maas, A. Borissov, J. Wendland, A. Brüll, M. Bouwhuis, Dirk Ryckbosch, B. Tipton, H. Böttcher, D. H. Potterveld, S. F. Pate, H. Marukyan, F. Meissner, Jeffrey Brack, E. De Sanctis, Franco Garibaldi, G. Hofman, C. A. Miller, R. P. Redwine, J. van Hunen, Martin Raithel, Ralf Hertenberger, J. Franz, K. Oganessyan, L. G. Greeniaus, C. Weiskopf, J. Ely, Thomas O'Neill, K. Hafidi, Eugenio Nappi, A. Schwind, V. Vikhrov, V. Rappoport, J. Kanesaka, Manuella Vincter, W.H.A. Hesselink, Ross Milner, K. P. Schüler, F. Sato, E. C. Aschenauer, D. Hasch, V. Shutov, J. J. M. Steijger, G. Rakness, T. Wise, A. Laziev, Y. Holler, V. A. Kozlov, S. Yoneyama, N. Koch, F. Schmidt, A. Nagaitsev, Wolfgang Lorenzon, Michel Vetterli, M. Beckmann, J. F. J. van den Brand, B. Bains, M. C. Simani, Erika Garutti, N. Akopov, P.K.A. de Witt Huberts, Valeria Muccifora, A. Gute, Alessandra Fantoni, I. Sanjiev, E. Avetissian, Nicola Bianchi, O. Mikloukho, A. Nass, Peter Jung, M. Düren, R. Mussa, Naomi C R Makins, S. Tessarin, M. Ehrenfried, R. De Leo, F. Menden, Adel Terkulov, S. Yen, Ralf Kaiser, Y. Gärber, E. Steffens, G. Gavrilov, A. Simon, B. R. Owen, A. Fechtchenko, A. Jgoun, M. Henoch, K. Suetsugu, Hiroaki Kobayashi, P. Bailey, P.W. Green, H. E. Jackson, V. G. Krivokhijine, C. Baumgarten, P. Kitching, D. Robinson, B. Krauss, C. Scarlett, F.H. Heinsius, Frank Ellinghaus, E. R. Kinney, Y. Naryshkin, S. Belostotski, (Astro)-Particles Physics, and Photo Conversion Materials
Subjects: HERMES experiment, Particle physics, Photon, media_common.quotation_subject, interference, General Physics and Astronomy, HERMES, dependence [helicity], Asymmetry, High Energy Physics - Experiment, 24.85.+p, Nuclear physics, 13.60.Fz, ddc:550, deep inelastic scattering [positron p], 26.7 GeV, Nuclear Experiment, NUCLEON, media_common, Physics, longitudinal [polarization], Scattering, ELECTROPRODUCTION, 14.20.Dh, Compton scattering, DESY, HERA, Bethe-Heitler [approximation], DESY HERA Stor, asymmetry [angular distribution], off-shell [Compton scattering], analyzing power, Physics::Accelerator Physics, High Energy Physics::Experiment, polarized beam [positron], electroproduction [photon], Beam (structure), experimental results
Abstract: The beam-spin asymmetry in hard electroproduction of photons has been measured for the first time. The data have been accumulated by the HERMES experiment at DESY using the HERA 27.6 GeV longitudinally polarized positron beam and an unpolarized hydrogen gas target. The asymmetry in the azimuthal distribution of the produced photons in the angle phi relative to the lepton scattering plane was determined with respect to the helicity state of the incoming positron beam. The beam-spin analyzing power in the sin(phi) moment was measured to be -0.23 +/- 0.04(stat) +/- 0.03(syst) in the missing-mass range below 1.7 GeV. The observed asymmetry is attributed to the interference of the Bethe-Heitler and deeply-virtual Compton scattering processes., Comment: 6 pages, 5 figures, revised experimental description
Published: 2001

23. Double-hadron leptoproduction in the nuclear medium.

Author: Airapetian A, Akopov N, Akopov Z, Amarian M, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Belostotski S, Bianchi N, Blok HP, Böttcher H, Borissov A, Borysenko A, Brüll A, Bryzgalov V, Capiluppi M, Capitani GP, Ciullo G, Contalbrigo M, Dalpiaz PF, Deconinck W, De Leo R, Demey M, De Nardo L, De Sanctis E, Devitsin E, Diefenthaler M, Di Nezza P, Dreschler J, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Fabbri R, Fantoni A, Felawka L, Frullani S, Funel A, Gapienko G, Gapienko V, Garibaldi F, Garrow K, Gavrilov G, Gharibyan V, Giordano F, Grebeniouk O, Gregor IM, Griffioen K, Guler H, Hadjidakis C, Hartig M, Hasch D, Hasegawa T, Hesselink WH, Hillenbrand A, Hoek M, Holler Y, Hommez B, Hristova I, Iarygin G, Ivanilov A, Izotov A, Jackson HE, Jgoun A, Kaiser R, Keri T, Kinney E, Kisselev A, Kobayashi T, Kopytin M, Korotkov V, Kozlov V, Krauss B, Kravchenko P, Krivokhijine VG, Lagamba L, Lapikás L, Lenisa P, Liebing P, Linden-Levy LA, Lorenzon W, Lu J, Lu S, Ma BQ, Maiheu B, Makins NC, Mao Y, Marianski B, Marukyan H, Masoli F, Mexner V, Meyners N, Michler T, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Murray M, Nagaitsev A, Nappi E, Naryshkin Y, Negodaev M, Nowak WD, Ohsuga H, Osborne A, Perez-Benito R, Pickert N, Raithel M, Reggiani D, Reimer PE, Reischl A, Roelon AR, Riedl C, Rith K, Rosner G, Rostomyan A, Rubacek L, Rubin J, Ryckbosch D, Salomatin Y, Sanjiev I, Savin I, Schäfer A, Schnell G, Schüler KP, Seele J, Seidl R, Seitz B, Shearer C, Shibata TA, Shutov V, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stenzel H, Stewart J, Stinzing F, Streit J, Tait P, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Trzcinski A, Tytgat M, Vandenbroucke A, van der Nat PB, van der Steenhoven G, van Haarlem Y, Veretennikov D, Vikhrov V, Vogel C, Wang S, Ye Y, Ye Z, Yen S, Zihlmann B, and Zupranski P
Abstract: The first measurements of double-hadron production in deep-inelastic scattering within the nuclear medium were made with the HERMES spectrometer at DESY HERA using a 27.6 GeV positron beam. By comparing data for deuterium, nitrogen, krypton, and xenon nuclei, the influence of the nuclear medium on the ratio of double-hadron to single-hadron yields was investigated. Nuclear effects on the additional hadron are clearly observed, but with little or no difference among nitrogen, krypton, or xenon, and with smaller magnitude than effects seen on previously measured single-hadron multiplicities. The data are compared with models based on partonic energy loss or prehadronic scattering and with a model based on a purely absorptive treatment of the final-state interactions. Thus, the double-hadron ratio provides an additional tool for studying modifications of hadronization in nuclear matter.
Published: 2006
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24. Measurement of the tensor structure function b1 of the deuteron.

Author: Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Balin D, Baturin V, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Borysenko A, Bouwhuis M, Brack J, Brüll A, Bryzgalov V, Capitani GP, Chen T, Chiang HC, Ciullo G, Contalbrigo M, Dalpiaz PF, De Leo R, Demey M, De Nardo L, De Sanctis E, Devitsin E, Di Nezza P, Dreschler J, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Fox B, Frullani S, Gapienko G, Gapienko V, Garibaldi F, Garrow K, Garutti E, Gaskell D, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Greeniaus LG, Gregor IM, Hafidi K, Hartig M, Hasch D, Heesbeen D, Henoch M, Hertenberger R, Hesselink WH, Hillenbrand A, Hoek M, Holler Y, Hommez B, Iarygin G, Ivanilov A, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Linden-Levy LA, Lipka K, Lorenzon W, Lu H, Lu J, Lu S, Ma BQ, Maiheu B, Makins NC, Mao Y, Marianski B, Marukyan H, Masoli F, Mexner V, Meyners N, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaev M, Nowak WD, Oganessyan K, Ohsuga H, Pickert N, Potashov S, Potterveld DH, Raithel M, Reggiani D, Reimer PE, Reischl A, Reolon AR, Riedl C, Rith K, Rosner G, Rostomyan A, Rubacek L, Rubin J, Ryckbosch D, Salomatin Y, Sanjiev I, Savin I, Schäfer A, Schill C, Schnell G, Schüler KP, Seele J, Seidl R, Seitz B, Shanidze R, Shearer C, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stenzel H, Stewart J, Stinzing F, Stösslein U, Tait P, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Tkabladze A, Trzcinski A, Tytgat M, Vandenbroucke A, van der Nat PB, van der Steenhoven G, Vetterli MC, Vikhrov V, Vincter MG, Vogel C, Vogt M, Volmer J, Weiskopf C, Wendland J, Wilbert J, Ye Y, Ye Z, Yen S, Zihlmann B, and Zupranski P
Abstract: The Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry A(d)zz and the tensor structure function b(d)1 for average values of the Bjorken variable 0.01< <0.45 and of the negative of the squared four-momentum transfer 0.5 GeV2 < <5 GeV2. The quantities A(d)zz and b(d)1 are found to be nonzero. The rise of b(d)1 for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering.
Published: 2005
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25. Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target.

Author: Airapetian A, Akopov N, Akopov Z, Amarian M, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bacchetta A, Bailey P, Balin D, Beckmann M, Belostotski S, Bianchi N, Blok HP, Böttcher H, Borissov A, Borysenko A, Bouwhuis M, Brüll A, Bryzgalov V, Capitani GP, Cappiluppi M, Chen T, Ciullo G, Contalbrigo M, Dalpiaz PF, Leo RD, Demey M, Nardo LD, Sanctis ED, Devitsin E, Nezza PD, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Frullani S, Gapienko G, Gapienko V, Garibaldi F, Garrow K, Gavrilov G, Gharibyan V, Grebeniouk O, Gregor IM, Hadjidakis C, Hafidi K, Hartig M, Hasch D, Henoch M, Hesselink WH, Hillenbrand A, Hoek M, Holler Y, Hommez B, Hristova I, Iarygin G, Ilyichev A, Ivanilov A, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Kobayashi T, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Linden-Levy LA, Lorenzon W, Lu H, Lu J, Lu S, Ma BQ, Maiheu B, Makins NC, Mao Y, Marianski B, Marukyan H, Masoli F, Mexner V, Meyners N, Michler T, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaev M, Nowak WD, Oganessyan K, Ohsuga H, Osborne A, Pickert N, Potterveld DH, Raithel M, Reggiani D, Reimer PE, Reischl A, Reolon AR, Riedl C, Rith K, Rosner G, Rostomyan A, Rubacek L, Rubin J, Ryckbosch D, Salomatin Y, Sanjiev I, Savin I, Schäfer A, Schill C, Schnell G, Schüler KP, Seele J, Seidl R, Seitz B, Shanidze R, Shearer C, Shibata TA, Shutov V, Sinram K, Sommer W, Stancari M, Statera M, Steffens E, Steijger JJ, Stenzel H, Stewart J, Stinzing F, Tait P, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Trzcinski A, Tytgat M, Vandenbroucke A, van der Nat PB, van der Steenhoven G, van Haarlem Y, Vetterli MC, Vikhrov V, Vincter MG, Vogel C, Volmer J, Wang S, Wendland J, Wilbert J, Smit GY, Ye Y, Ye Z, Yen S, Zihlmann B, and Zupranski P
Abstract: Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (phi) and the target spin axis (phi(S)) about the virtual-photon direction and relative to the lepton scattering plane. The extracted Fourier component sin((phi+phi(S))(pi)(UT) is a signal of the previously unmeasured quark transversity distribution, in conjunction with the Collins fragmentation function, also unknown. The component sin((phi-phi(S)(pi)(UT) arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production.
Published: 2005
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26. Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering.

Author: Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Baturin V, Baumgarten C, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Bouwhuis M, Brack J, Brüll A, Bryzgalov V, Capitani GP, Chiang HC, Ciullo G, Contalbrigo M, Dalpiaz PF, De Leo R, De Nardo L, De Sanctis E, Devitsin E, Di Nezza P, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Ely J, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Fox B, Franz J, Frullani S, Gärber Y, Gapienko G, Gapienko V, Garibaldi F, Garrow K, Garutti E, Gaskell D, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Greeniaus LG, Hafidi K, Hartig M, Hasch D, Heesbeen D, Henoch M, Hertenberger R, Hesselink WH, Hillenbrand A, Hoek M, Holler Y, Hommez B, Iarygin G, Ivanilov A, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Königsmann K, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Lindemann T, Lipka K, Lorenzon W, Lu J, Maiheu B, Makins NC, Marianski B, Marukyan H, Masoli F, Mexner V, Meyners N, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaev M, Nowak WD, Oganessyan K, Ohsuga H, Orlandi G, Pickert N, Potashov S, Potterveld DH, Raithel M, Reggiani D, Reimer PE, Reischl A, Reolon AR, Riedl C, Rith K, Rosner G, Rostomyan A, Rubacek L, Ryckbosch D, Salomatin Y, Sanjiev I, Savin I, Scarlett C, Schäfer A, Schill C, Schnell G, Schüler KP, Schwind A, Seele J, Seidl R, Seitz B, Shanidze R, Shearer C, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stewart J, Stösslein U, Tait P, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Tkabladze A, Trzcinski A, Tytgat M, Vandenbroucke A, Van Der Nat P, Van Der Steenhoven G, Vetterli MC, Vikhrov V, Vincter MG, Visser J, Vogel C, Vogt M, Volmer J, Weiskopf C, Wendland J, Wilbert J, Ybeles Smit G, Yen S, Zihlmann B, Zohrabian H, and Zupranski P
Abstract: Double-spin asymmetries of semiinclusive cross sections for the production of identified pions and kaons have been measured in deep inelastic scattering of polarized positrons on a polarized deuterium target. Five helicity distributions including those for three sea quark flavors were extracted from these data together with reanalyzed previous data for identified pions from a hydrogen target. These distributions are consistent with zero for all three sea flavors. A recently predicted flavor asymmetry in the polarization of the light quark sea appears to be disfavored by the data.
Published: 2004
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27. Evidence for quark-hadron duality in the proton spin asymmetry A1.

Author: Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Aschenauer EC, Avakian H, Avakian R, Avetissian A, Avetissian E, Bailey P, Baturin V, Baumgarten C, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Bouhali O, Bouwhuis M, Brack J, Brauksiepe S, Brüll A, Brunn I, Bulten HJ, Capitani GP, Cisbani E, Ciullo G, Court GR, Dalpiaz PF, De Leo R, De Nardo L, De Sanctis E, Devitsin E, de Witt Huberts PK, Di Nezza P, Düren M, Ehrenfried M, Elbakian G, Ellinghaus F, Elschenbroich U, Ely J, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Filippone BW, Fischer H, Fox B, Franz J, Frullani S, Gärber Y, Gapienko V, Garibaldi F, Garutti E, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Green PW, Greeniaus LG, Gute A, Haeberli W, Hafidi K, Hartig M, Hasch D, Heesbeen D, Heinsius FH, Henoch M, Hertenberger R, Hesselink WH, Hofman G, Holler Y, Holt RJ, Hommez B, Iarygin G, Izotov A, Jackson HE, Jgoun A, Jung P, Kaiser R, Kinney E, Kisselev A, Kitching P, Königsmann K, Kolster H, Kopytin M, Korotkov V, Kotik E, Kozlov V, Krauss B, Krivokhijine VG, Kyle G, Lagamba L, Laziev A, Lenisa P, Liebing P, Lindemann T, Lorenzon W, Maas A, Makins NC, Marukyan H, Masoli F, Menden F, Mexner V, Meyners N, Mikloukho O, Miller CA, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaeva K, Nowak WD, Oganessyan K, Orlandi G, Podiatchev S, Potashov S, Potterveld DH, Raithel M, Rappoport V, Reggiani D, Reimer P, Reischl A, Reolon AR, Rith K, Rostomyan A, Ryckbosch D, Sakemi Y, Sanjiev I, Sato F, Savin I, Scarlett C, Schäfer A, Schill C, Schmidt F, Schnell G, Schüler KP, Schwind A, Seibert J, Seitz B, Shanidze R, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Steffens E, Steijger JJ, Stewart J, Stösslein U, Suetsugu K, Taroian S, Terkulov A, Tessarin S, Thomas E, Tipton B, Tytgat M, Urciuoli GM, van den Brand JF, van der Steenhoven G, van de Vyver R, Vetterli MC, Vikhrov V, Vincter MG, Visser J, Volmer J, Weiskopf C, Wendland J, Wilbert J, Wise T, Yen S, Yoneyama S, Zihlmann B, and Zohrabian H
Abstract: Spin-dependent lepton-nucleon scattering data have been used to investigate the validity of the concept of quark-hadron duality for the spin asymmetry A1. Longitudinally polarized positrons were scattered off a longitudinally polarized hydrogen target for values of Q2 between 1.2 and 12 GeV2 and values of W2 between 1 and 4 GeV2. The average double-spin asymmetry in the nucleon resonance region is found to agree with that measured in deep-inelastic scattering at the same values of the Bjorken scaling variable x. This finding implies that the description of A1 in terms of quark degrees of freedom is valid also in the nucleon resonance region for values of Q2 above 1.6 GeV2.
Published: 2003
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28. Q2 dependence of nuclear transparency for exclusive rho0 production.

Author: Airapetian A, Akopov N, Akopov Z, Amarian M, Ammosov VV, Andrus A, Aschenauer EC, Augustyniak W, Avakian R, Avetissian A, Avetissian E, Bailey P, Baturin V, Baumgarten C, Beckmann M, Belostotski S, Bernreuther S, Bianchi N, Blok HP, Böttcher H, Borissov A, Bouwhuis M, Brack J, Brüll A, Brunn I, Capitani GP, Chiang HC, Ciullo G, Contalbrigo M, Court GR, Dalpiaz PF, De Leo R, De Nardo L, De Sanctis E, Devitsin E, Di Nezza P, Düren M, Ehrenfried M, Elalaoui-Moulay A, Elbakian G, Ellinghaus F, Elschenbroich U, Ely J, Fabbri R, Fantoni A, Fechtchenko A, Felawka L, Fox B, Franz J, Frullani S, Gärber Y, Gapienko G, Gapienko V, Garibaldi F, Garutti E, Gaskell D, Gavrilov G, Gharibyan V, Graw G, Grebeniouk O, Greeniaus LG, Haeberli W, Hafidi K, Hartig M, Hasch D, Heesbeen D, Henoch M, Hertenberger R, Hesselink WH, Hillenbrand A, Holler Y, Hommez B, Iarygin G, Izotov A, Jackson HE, Jgoun A, Kaiser R, Kinney E, Kisselev A, Königsmann K, Kolster H, Kopytin M, Korotkov V, Kozlov V, Krauss B, Krivokhijine VG, Lagamba L, Lapikás L, Laziev A, Lenisa P, Liebing P, Lindemann T, Lorenzon W, Makins NC, Marukyan H, Masoli F, Menden F, Mexner V, Meyners N, Mikloukho O, Miller CA, Miyachi Y, Muccifora V, Nagaitsev A, Nappi E, Naryshkin Y, Nass A, Negodaeva K, Nowak WD, Oganessyan K, Ohsuga H, Orlandi G, Podiatchev S, Potashov S, Potterveld DH, Raithel M, Reggiani D, Reimer P, Reischl A, Reolon AR, Rith K, Rosner G, Rostomyan A, Ryckbosch D, Sanjiev I, Savin I, Scarlett C, Schäfer A, Schill C, Schnell G, Schüler KP, Schwind A, Seibert J, Seitz B, Shanidze R, Shibata TA, Shutov V, Simani MC, Sinram K, Stancari M, Statera M, Steffens E, Steijger JJ, Stewart J, Stösslein U, Tanaka H, Taroian S, Tchuiko B, Terkulov A, Tessarin S, Thomas E, Tkabladze A, Trzcinski A, Tytgat M, Urciuoli GM, Van Der Nat P, Van Der Steenhoven G, Van De Vyver R, Vetterli MC, Vikhrov V, Vincter MG, Visser J, Vogt M, Volmer J, Weiskopf C, Wendland J, Wilbert J, Wise T, Yen S, Yoneyama S, Zihlmann B, Zohrabian H, and Zupranski P
Abstract: Exclusive coherent and incoherent electroproduction of the rho(0) meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (l(c)), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon (-Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing l(c) for coherent (incoherent) rho(0) electroproduction. For fixed l(c), a rise of nuclear transparency with Q2 is observed for both coherent and incoherent rho(0) production, which is in agreement with theoretical calculations of color transparency.
Published: 2003
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28 results on '"I. Sanjiev"'

1. Measurement of parton distributions of strange quarks in the nucleon from charged-kaon production in deep-inelastic scattering on the deuteron

2. Hard exclusive electroproduction of π+π− pairs

3. Measurement of Azimuthal Asymmetries With Respect To Both Beam Charge and Transverse Target Polarization in Exclusive Electroproduction of Real Photons

4. Transverse polarization ofΛandΛ¯hyperons in quasireal photoproduction

5. Precise determination of the spin structure function g(1) of the proton, deuteron, and neutron

6. Beam-charge azimuthal asymmetry and deeply virtual Compton scattering

7. Beam-spin asymmetries in the azimuthal distribution of pion electroproduction

8. Double-hadron leptoproduction in the nuclear medium

9. Longitudinal spin transfer to the Lambda hyperon in semiinclusive deep-inelastic scattering

10. Measurement of the tensor structure function b1 of the deuteron

11. Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target

12. Search for an exoticS=−2,Q=−2baryon resonance at a mass near 1862 MeV in quasireal photoproduction

13. Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering

14. The HERMES Polarized Hydrogen and Deuterium Gas Target in the HERA Electron Storage Ring

15. Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction

16. Q2Dependence of Nuclear Transparency for Exclusiveρ0Production

17. Quark fragmentation to π±, π0, K±, p and p_bar in the nuclear environment

18. Q2 dependence of nuclear transparency for exclusive rho0 production

19. Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$

20. Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

21. Single-spin azimuthal asymmetry in exclusive electroproduction of pi^+ mesons

22. Measurement of the Beam-Spin Azimuthal Asymmetry associated with Deep Virtual Compton Scattering

23. Double-hadron leptoproduction in the nuclear medium.

24. Measurement of the tensor structure function b1 of the deuteron.

25. Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target.

26. Flavor decomposition of the sea-quark helicity distributions in the nucleon from semiinclusive deep inelastic scattering.

27. Evidence for quark-hadron duality in the proton spin asymmetry A1.

28. Q2 dependence of nuclear transparency for exclusive rho0 production.

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