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10 results on '"Sinram, K"'

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

Author

Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Ammosov, V.V., Aschenauer, E.C., Avakian, H., Avakian, R., Avetissian, A., Avetissian, E., Bailey, P., Baturin, V., Baumgarten, C., Beckmann, M., Belostotski, S., Bernreuther, S., Bianchi, N., Blok, H.P., Bottcher, H., Borissov, A., Bouhali, O., Bouwhuis, M., Brack, J., Brauksiepe, S., Brull, A., Brunn, I., Bulten, H.J., Capitani, G.P., Cisbani, E., Ciullo, G., Court, G.R., Dalpiaz, P.F., De Leo, R., De Nardo, L., De Sanctis, E., Devitsin, E., Witt Huberts, P.K.A., Di Nezza, P., Duren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Elschenbroich, U., Ely, J., Fabbri, R., Fantoni, A., Fechtchenko, A., Felawka, L., Filippone, B.W., Fischer, H., Fox, B., Franz, J., Frullani, S., Garber, Y., Gapienko, V., Garibaldi, F., Garutti, E., Gavrilov, G., Gharibyan, V., Graw, G., Grebeniouk, O., Green, P.W., Greeniaus, L.G., Gute, A., Haeberli, W., Hafidi, K., Hartig, M., Hasch, D., Heesbeen, D., Heinsius, F.H., Henoch, M., Hertenberger, R., Hesselink, W.H.A., Hofman, G., Holler, Y., Holt, R.J., Hommez, B., Iarygin, G., Izotov, A., Jackson, H.E., Jgoun, A., Jung, P., Kaiser, R., Kinney, E., Kisselev, A., Kitching, P., Konigsmann, K., Kolster, H., Kopytin, M., Korotkov, V., Kotik, E., Kozlov, V., Krauss, B., Krivokhijine, V.G., Kyle, G., Lagamba, L., Laziev, A., Lenisa, P., Liebing, P., Lindemann, T., Lorenzon, W., Maas, A., Makins, N.C.R., Marukyan, H., Masoli, F., Menden, F., Mexner, V., Meyners, N., Mikloukho, O., Miller, C.A., Muccifora, V., Nagaitsev, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaeva, K., Nowak, W.D., Oganessyan, K., Orlandi, G., Podiatchev, S., Potashov, S., Potterveld, D.H., Raithel, M., Rappoport, V., Reggiani, D., Reimer, P., Reischl, A., Reolon, A.R., Rith, K., Rostomyan, A., Ryckbosch, D., Sakemi, Y., Sanjiev, I., Sato, F., Savin, I., Scarlett, C., Schafer, A., Schill, C., SChmidt, F., Schnell, G., Schuler, K.P., Schwind, A., Seibert, J., Seitz, B., Shanidze, R., Shibata, T.A., Shutov, V., Simani, M.C., Sinram, K., Stancari, M., Steffens, E., Steijger, J.J.M., Stewart, J., Stosslein, U., Suetsugu, K., Taroian, S., Terkulov, A., Tessarin, S., Thomas, E., Tipton, B., Tytgat, M., Urciuoli, G.M., van den Brand, J.F.J., van der Steenhoven, G., Van de Vyver, R., Vetterli, M.C., Vikhrov, V., Vincter, M.G., Visser, J., Volmer, J., Weiskopf, C., Wendland, J., Wilbert, J., Wise, T., Yen, S., Yoneyama, S., Zihlmann, B., and Zohrabian, H.

Subjects
High Energy Physics::Experiment, QC
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 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 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

2. Measurement of longitudinal spin transfer to Lambda hyperons in deep-inelastic lepton scattering

Author

Airapetian, A., Akopov, N., Amarian, M., Aschenauer, E.C., Avakian, H., Avakian, R., Avetissian, A., Bains, B., Baumgarten, C., Beckmann, M., Belostotski, S., Belz, J.E., Benisch, T., Bernreuther, S., Bianchi, N., Blouw, J., Bottcher, H., Borissov, A., Bouwhuis, M., Brack, J., Brauksiepe, S., Braun, B., Bray, B., Brons, S., Bruckner, W., Brull, A., Bruins, E.E.W., Bulten, H.J., Capitani, G.P., Carter, P., Chumney, P., Cisbani, E., Court, G.R., Dalpiaz, P.F., De Sanctis, E., De Schepper, D., Devitsin, E., Witt Huberts, P.K.A., Di Nezza, P., Duren, M., Dvoredsky, A., Elbakian, G., Ely, J., Fantoni, A., Fechtchenko, A., Ferstl, M., Fiedler, K., Filippone, B.W., Fischer, H., Fox, B., Franz, J., Frullani, S., Funk, M.A., Garber, Y., Gao, H., Garibaldi, F., Gavrilov, G., Geiger, P., Gharibyan, V., Golendukhin, A., Graw, G., Grebeniouk, O., Green, P.W., Greeniaus, L.G., Grosshauser, C., Guidal, M., Gute, A., Gyurjyan, V., Haas, J.P., Haeberli, W., Hausser, O., Hansen, J.O., Hartig, M., Hasch, D., Heinsius, F.H., Henderson, R., Henoch, M., Hertenberger, R., Holler, Y., Holt, R.J., Hoprich, W., Ihssen, H., Iodice, M., Izotov, A., Jackson, H.E., Jgoun, A., Kaiser, R., Kinney, E., Kirsch, M., Kisselev, A., Kitching, P., Kobayashi, H., Koch, N., Konigsmann, K., Kolstein, M., Kolster, H., Korotkov, V., Korsch, W., Kozlov, V., Kramer, L.H., Krivokhijine, V.G., Kurisuno, M., Kyle, G., Lachnit, W., Lenisa, P., Lorenzon, W., Makins, N.C.R., Manaenkov, S.I., Martens, F.K., Martin, J.W., Masoli, F., Mateos, A., McAndrew, M., McIlhany, K., Mckeown, R.D., Meissner, F., Menden, F., Metz, A., Meyners, N., Mikloukho, O., Miller, C.A., Miller, M.A., Milner, R., Most, A., Muccifora, V., Mussa, R., Nagaitsev, A., Naryshkin, Y., Nathan, A.M., Neunreither, F., Niczyporuk, J.M., Nowak, W.D., Nupieri, M., O'Neill, T.G., Openshaw, R., Ouyang, J., Owen, B.R., Papavassiliou, V., Pate, S.F., Pitt, M., Potashov, S., Potterveld, D.H., Rakness, G., Reali, A., Redwine, R., Reolon, A.R., Ristinen, R., Rith, K., Rossi, P., Rudnitsky, S., Ruh, M., Ryckbosch, D., Sakemi, Y., Savin, I., Scarlett, C., Schmidt, F., Schmitt, H., Schnell, G., Schuler, K.P., Schwind, A., Seibert, J., Shibata, T.A., Shibatani, K., Shin, T., Shutov, V., Simani, C., Simon, A., Sinram, K., Slavich, P., Spengos, M., Steffens, E., Stenger, J., Stewart, J., Stosslein, U., Sutter, M., Tallini, H., Taroian, S., Terkulov, A., Thomas, E., Tipton, B., Tytgat, M., Urciuoli, G.M., van den Brand, J.F.J., van der Steenhoven, G., Van de Vyver, R., van Hunen, J.J., Vetterli, M.C., Vikhrov, V., Vincter, M.G., Visser, J., Volk, E., Wander, W., Wendland, J., Williamson, S.E., Wise, T., Woller, K., Yoneyama, S., and Zohrabian, H.

Subjects
High Energy Physics::Experiment, QC
Abstract

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the DESY HERA storage ring. For an average fractional energy transfer [z]=0.45, the longitudinal spin transfer from the virtual photon to the Lambda has been extracted. The spin transfer along the Lambda momentum direction is found to be 0.11+or-0.17(stat)+or-0.03(syst); similar values are found for other possible choices for the longitudinal spin direction of the Lambda . This result is the most precise value obtained to date from deep-inelastic scattering with charged lepton beams, and is sensitive to polarized up quark fragmentation to hyperon states. The experimental result is found to be in general agreement with various models of the Lambda spin content, and is consistent with the assumption of helicity conservation in the fragmentation process

Published
2001

3. Measurement of the Spin Asymmetry in the Photoproduction of Pairs of High- pT Hadrons at HERMES

Author

Airapetian, A., Akopov, N., Amarian, M., Aschenauer, E. C., Avakian, H., Avakian, R., Avetissian, A., Bains, B., Baumgarten, C., Beckmann, M., Belostotski, S., Belz, J. E., Benisch, Th., Bernreuther, S., Bianchi, N., Blouw, J., Böttcher, H., Borissov, A., Brack, J., Brauksiepe, S., Braun, B., Brückner, W., Brüll, A., Bulten, H. J., Capitani, G. P., Carter, P., Chumney, P., Cisbani, E., Court, G. R., Dalpiaz, P. F., De-Sanctis, E., De-Schepper, D., Devitsin, E., de-Witt-Huberts, P. K. A., Di-Nezza, P., Düren, M., Dvoredsky, A., Elbakian, G., Ely, J., Fantoni, A., Ferstl, M., Fiedler, K., Filippone, B. W., Fischer, H., Fox, B., Franz, J., Frullani, S., Funk, M.-A., Gärber, Y., Garibaldi, F., Gavrilov, G., Geiger, P., Gharibyan, V., Golendukhin, A., Graw, G., Grebeniouk, O., Green, P. W., Greeniaus, L. G., Grosshauser, C., Guidal, M., Gute, A., Haeberli, W., Hansen, J.-O., Hasch, D., Häusser, O., Heinsius, F. H., Henderson, R., Henoch, M., Hertenberger, R., Holler, Y., Holt, R. J., Hoprich, W., Ihssen, H., Iodice, M., Izotov, A., Jackson, H. E., Jgoun, A., Kaiser, R., Kinney, E., Kisselev, A., Kitching, P., Kobayashi, H., Koch, N., Königsmann, K., Kolstein, M., Kolster, H., Korotkov, V., Korsch, W., Kozlov, V., Kramer, L. H., Kurisuno, M., Kyle, G., Lachnit, W., Lorenzon, W., Makins, N. C. R., Martens, F. K., Martin, J. W., Masoli, F., Mateos, A., McAndrew, M., McIlhany, K., McKeown, R. D., Meissner, F., Menden, F. M., Metz, A., Meyners, N., Mikloukho, O., Miller, C. A., Miller, M. A., Milner, R., Most, A., Muccifora, V., Naryshkin, Y., Nathan, A. M., Neunreither, F., Niczyporuk, M., Nowak, W.-D., O'Neill, T. G., Openshaw, R., Ouyang, J., Owen, B. R., Pate, S. F., Potashov, S., Potterveld, D. H., Rakness, G., Redwine, R., Reolon, A. R., Ristinen, R., Rith, K., Rossi, P., Rudnitsky, S., Ruh, M., Ryckbosch, D., Sakemi, Y., Scarlett, C., Schäfer, A., Schmidt, F., Schmitt, H., Schnell, G., Schüler, K. P., Schwind, A., Seibert, J., Shibata, T.-A., Shibatani, K., Shin, T., Shutov, V., Simani, C., Simon, A., Sinram, K., Slavich, P., Spengos, M., Steffens, E., Stenger, J., Stewart, J., Stoesslein, U., Sutter, M., Tallini, H., Taroian, S., Terkulov, A., Tipton, B., Tytgat, M., Uriuoli, G. M., van-de-Vyver, R., van-den-Brand, J. F. J., van-der-Steenhoven, G., van-Hunen, J. J., Vetterli, M. C., Vikhrov, V., Vincter, M. G., Visser, J., Volk, E., Wander, W., Wendland, J., Williamson, S. E., Wise, T., Woller, K., Yoneyama, S., and Zohrabian, H.

Subjects
High Energy Physics::Experiment, Nuclear Experiment
Abstract

We present a measurement of the longitudinal spin asymmetry A|| in photoproduction of pairs of hadrons with high transverse momentum pT. Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h^+h^- pairs with _(pT)^(h1)>1.5GeV/c and _(pT)^(h2)>1.0GeV/c, the measured asymmetry is A_(||) = -0.28±0.12(stat)±0.02(syst). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization.

Published
2000

4. Observation of a coherence length effect in exclusive ρ(0) electroproduction

Author

Ackerstaff, K., Airapetian, A., Akopov, N., Akushevich, I., Amarian, M., Aschenauer, E. C., Avakian, H., Avakian, R., Avetissian, A., Bains, B., Barrow, S., Baumgarten, C., Beckmann, M., Belostotski, St., Belz, J. E., Benisch, Th., Bernreuther, S., Bianchi, N., Blanchard, S., Blouw, J., Böttcher, H., Borissov, A., Brack, J., Brauksiepe, S., Braun, B., Bray, B., Brons, St., Brückner, W., Brüll, A., Bruins, E. E. W., Bulten, H. J., Cadman, R. V., Capitani, G. P., Carter, P., Chumney, P., Cisbani, E., Court, G. R., Dalpiaz, P. F., Delheij, P. P. J., De Sanctis, E., De Schepper, D., Devitsin, E., de Witt Huberts, P. K. A., Di Nezza, P., Düren, M., Dvoredsky, A., Elbakian, G., Ely, J., Emerson, J., Fantoni, A., Fechtchenko, A., Ferstl, M., Fick, D., Fiedler, K., Filippone, B. W., Fischer, H., Fortune, H. T., Fox, B., Frabetti, S., Franz, J., Frullani, S., Funk, M.-A., Gagunashvili, N. D., Galumian, P., Gao, H., Gärber, Y., Garibaldi, F., Gavrilov, G., Geiger, P., Gharibyan, V., Giordjian, V., Golendukhin, A., Graw, G., Grebeniouk, O., Green, P. W., Greeniaus, L. G., Grosshauser, C., Guidal, M. G., Gute, A., Gyurjyan, V., Haas, J. P., Haeberli, W., Hansen, J.-O., Hasch, D., Häusser, O., Heinsius, F. H., Henderson, R. S., Henkes, Th., Henoch, M., Hertenberger, R., Holler, Y., Holt, R. J., Hoprich, W., Ihssen, H., Iodice, M., Izotov, A., Jackson, H. E., Jgoun, A., Jones, C., Kaiser, R., Kinney, E., Kirsch, M., Kisselev, A., Kitching, P., Kobayashi, H., Koch, N., Königsmann, K., Kolstein, M., Kolster, H., Korotkov, V., Korsch, W., Kozlov, V., Kramer, L. H., Krause, B., Krivokhijine, V. G., Kückes, M., Kümmell, F., Kyle, G., Lachnit, W., Lorenzon, W., Lung, A., Makins, N. C. R., Martens, F. K., Martin, J. W., Masoli, F., Mateos, A., McAndrew, M., McIlhany, K., McKeown, R. D., Meissner, F., Menden, F., Mercer, D., Metz, A., Meyners, N., Mikloukho, O., Miller, C. A., Miller, M. A., Milner, R. G., Mitsyn, V., Most, A., Mozzetti, R., Muccifora, V., Nagaitsev, A., Naryshkin, Y., Nathan, A. M., Neunreither, F., Niczyporuk, M., Nowak, W.-D., Nupieri, M., Oelwein, P., Ogami, H., O'Neill, T. G., Openshaw, R., Ouyang, J., Owen, B. R., Papavassiliou, V., Pate, S. F., Pitt, M., Poolman, H. R., Potashov, S., Potterveld, D. H., Povh, B., Rakness, G., Reali, A., Redwine, R., Reolon, A. R., Ristinen, R., Rith, K., Roloff, H., Röper, G., Rossi, P., Rudnitsky, S., Ruh, M., Ryckbosch, D., Sakemi, Y., Savin, I., Scarlett, C., Schmidt, F., Schmitt, H., Schnell, G., Schüler, K. P., Schwind, A., Seibert, J., Shibata, T.-A., Shin, T., Shutov, V., Simani, C., Simon, A., Sinram, K., Slavich, P., Sowinski, J., Spengos, M., Steffens, E., Stenger, J., Stewart, J., Stock, F., Stoesslein, U., Sutter, M., Tallini, H., Taroian, S., Terkulov, A., Thiessen, D. M., Thomas, E., Tipton, B., Trudel, A., Tytgat, M., Urciuoli, G. M., van Hunen, J. J., van de Vyver, R., van den Brand, J. F. J., van der Steenhoven, G., Vetterli, M. C., Vikhrov, V., Vincter, M., Visser, J., Volk, E., Wander, W., Welch, T. P., Williamson, S. E., Wise, T., Wölfel, T., Woller, K., Yoneyama, S., Zapfe-Düren, K., Zohrabian, H., and Zurmühle, R.

Subjects
High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract

Exclusive incoherent electroproduction of the ρ0(770) meson from 1H, 2H, 3He, and 14N targets has been studied by the HERMES experiment at squared four-momentum transfer Q^2>0.4 GeV^2 and positron energy loss ν from 9 to 20 GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the nuclear transparency, was found to decrease with increasing coherence length of quark-antiquark fluctuations of the virtual photon. The data provide clear evidence of the interaction of the quark-antiquark fluctuations with the nuclear medium.

Published
1999

5. 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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6. 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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7. 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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8. 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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9. 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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10. 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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