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1. Measurement of the Spin Asymmetry in the Photoproduction of Pairs of High-pTHadrons at HERMES

Author

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

Subjects
HERMES experiment, Physics, Particle physics, media_common.quotation_subject, Hadron, General Physics and Astronomy, HERA, Polarization (waves), Deep inelastic scattering, Asymmetry, Gluon, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment, Storage ring, media_common
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
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2. Observation of a Coherence Length Effect in Exclusiveρ0Electroproduction

Author

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

Subjects
Physics, HERMES experiment, Particle physics, Meson, 010308 nuclear & particles physics, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, General Physics and Astronomy, Virtual particle, 01 natural sciences, Coherence length, Positron energy, Nuclear physics, Deuterium, Nuclear transparency, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
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
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3. Measurement of the proton spin structure function g(1)(p) with a pure hydrogen target

Author

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

Subjects
Nuclear and High Energy Physics, Particle physics, POLARIZATION, Hydrogen, Positron beam, FOS: Physical sciences, chemistry.chemical_element, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), DEUTERON STRUCTURE FUNCTIONS, 0103 physical sciences, Proton spin crisis, Nuclear Experiment, 010306 general physics, Physics, DEEP-INELASTIC-SCATTERING, Range (particle radiation), F-2(P), 010308 nuclear & particles physics, Scattering, Structure function, HERA, 3. Good health, chemistry, Physics::Accelerator Physics, High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, Storage ring
Abstract

A measurement of the proton spin structure function g1p(x,Q^2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021, Comment: 7 pages, 3 figures, 1 table, RevTeX latex

Published
1998
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4. COSY-11, an internal experimental facility for threshold measurements

Author

K. Zwoll, M. Jochmann, Paweł Moskal, D. Grzonka, H. Stockhorst, S. Martin, M. Wolke, A. Strzałkowski, G. Schepers, R. Santo, H. Gutschmidt, Ulf Bechstedt, T. Sefzick, H. Schneider, M. Rook, L. Jarczyk, R. Maier, J. Majewski, A. Budzanowski, K.H. Watzlawik, A. Khoukaz, R. Reinartz, R. Tölle, H. Stechemesser, P. Turek, U. Seddik, W. Oelert, J. T. Balewski, H. Dombrowski, M. Sokolowski, S. Bowes, K. Kilian, K.H. Diart, A. Misiak, M. Ziolkowski, D. Prasuhn, P. Wüstner, J. Dietrich, E. Roderburg, C. D. Goodman, C. Quentmeier, A. Schnase, S. Brauksiepe, F. Klehr, Jerzy Smyrski, W. Hamsink, A. Kozela, M. Köhler, A. Hardt, M. Karnadi, T. Lister, and R. Nellen

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Meson, Synchrotron, law.invention, Semiconductor detector, Nuclear physics, law, Dipole magnet, Cluster (physics), Nuclear Experiment, Instrumentation, Storage ring, Beam (structure)
Abstract

The COSY-11 installation is an internal experiment at the cooler synchrotron and storage ring COSY Julich. It has been designed for full geometrical acceptance close to threshold for meson production studies, especially in the 1 GeV/c2 mass range. The experimental setup makes use of a regular C-type COSY dipole magnet, following a cluster target, to separate reaction products from the beam and to analyze their momenta, thus allowing the observation of charged reaction products at small angles with beam energies close to threshold. Resonances will be identified by missing mass reconstructions from measured four-momenta of two outgoing protons in the predominantly studied pp → ppX reaction. In addition, charged mesons either produced directly or from decays of X will be detected. The different components of the experimental facility are presented.

Published
1996
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5. 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
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6. 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
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7. 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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8. 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
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9. The Q2 dependence of the generalized Gerasimov-Drell-Hearn integral for the proton

Author

A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, J. Arrington, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, B. Bains, C. Baumgarten, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H. Böttcher, A. Borissov, M. Bouwhuis, J. Brack, S. Brauksiepe, B. Braun, W. Brückner, A. Brüll, P. Budz, H.J. Bulten, G.P. Capitani, P. Carter, P. Chumney, E. Cisbani, 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, V. Djordjadze, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, A. Fantoni, A. Fechtchenko, M. Ferro-Luzzi, K. Fiedler, B.W. Filippone, H. Fischer, B. Fox, J. Franz, S. Frullani, Y. Gärber, F. Garibaldi, E. Garutti, G. Gavrilov, V. Gharibyan, A. Golendukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, A. Gute, W. Haeberli, M. Hartig, D. Hasch, D. Heesbeen, F.H. Heinsius, M. Henoch, R. Hertenberger, W. Hesselink, P. Hoffmann-Rothe, G. Hofman, Y. Holler, R.J. Holt, B. Hommez, G. Iarygin, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, P. Jung, R. Kaiser, J. Kanesaka, E. Kinney, A. Kisselev, P. Kitching, H. Kobayashi, N. Koch, K. Königsmann, H. Kolster, V. Korotkov, E. Kotik, V. Kozlov, V.G. Krivokhijine, G. Kyle, L. Lagamba, A. Laziev, P. Lenisa, T. Lindemann, W. Lorenzon, N.C.R. Makins, J.W. Martin, H. Marukyan, F. Masoli, M. McAndrew, K. McIlhany, R.D. McKeown, F. Menden, A. Metz, N. Meyners, O. Mikloukho, C.A. Miller, R. Milner, V. Mitsyn, V. Muccifora, R. Mussa, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, K. Negodaeva, W.-D. Nowak, T.G. O'Neill, R. Openshaw, J. Ouyang, B.R. Owen, S.F. Pate, S. Potashov, D.H. Potterveld, G. Rakness, V. Rappoport, R. Redwine, D. Reggiani, A.R. Reolon, R. Ristinen, K. Rith, D. Robinson, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, A. Schäfer, C. Schill, F. Schmidt, G. Schnell, K.P. Schüler, A. Schwind, J. Seibert, B. Seitz, T.-A. Shibata, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, E. Steffens, J.J.M. Steijger, J. Stewart, U. Stösslein, K. Suetsugu, M. Sutter, H. Tallini, 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, J.J. van Hunen, M.C. Vetterli, V. Vikhrov, M.G. Vincter, J. Visser, E. Volk, C. Weiskopf, J. Wendland, J. Wilbert, T. Wise, S. Yen, S. Yoneyama, H. Zohrabian, (Astro)-Particles Physics, and Photo Conversion Materials

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Range (particle radiation), Proton, Nuclear Theory, FOS: Physical sciences, Virtual particle, Square (algebra), High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Quantum electrodynamics, High Energy Physics::Experiment, Twist, Nuclear Experiment, Sign (mathematics)
Abstract

The dependence on Q^2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the proton has been measured in the range 1.2 GeV^2 < Q^2 < 12 GeV^2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep-inelastic regions to this integral have been evaluated separately. The latter has been found to dominate for Q^2 > 3 GeV^2, while both contributions are important at low Q^2. The total integral shows no significant deviation from a 1/Q^2 behaviour in the measured Q^2 range, and thus no sign of large effects due to either nucleon-resonance excitations or non-leading twist., 9 pages, 3 figures, 1 table

Published
2000
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10. Determination of the Deep Inelastic Contribution to the generalised Gerasimov-Drell-Hearn Intregral for the Proton and Neutron

Author

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

Subjects
Nuclear and High Energy Physics, Particle physics, Proton, Nuclear Theory, PARTON MODEL, Virtual particle, FOS: Physical sciences, 01 natural sciences, High Energy Physics - Experiment, POLARIZED HE-3, SUM-RULES, Cross section (physics), High Energy Physics - Experiment (hep-ex), 0103 physical sciences, SCATTERING, Neutron, STRUCTURE-FUNCTION G(1)(N), 010306 general physics, Nuclear Experiment, NUCLEON, Quantum chromodynamics, Physics, 010308 nuclear & particles physics, Absorption cross section, Deep inelastic scattering, SPIN STRUCTURE-FUNCTION, RESONANCE REGION, High Energy Physics::Experiment, E-P, Nucleon
Abstract

The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2] for the proton and neutron have been determined from measurements of polarised cross section asymmetries in deep inelastic scattering of 27.5 GeV longitudinally polarised positrons from polarised 1H and 3He internal gas targets. The data were collected in the region above the nucleon resonances in the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the proton the contribution to the generalised Gerasimov-Drell-Hearn integral was found to be substantial and must be included for an accurate determination of the full integral. Furthermore the data are consistent with a QCD next-to-leading order fit based on previous deep inelastic scattering data. Therefore higher twist effects do not appear significant., 6 pages, 3 figures, 1 table, revtex

Published
1998
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11. The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering

Author

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

Subjects
Quark, Particle physics, Proton, media_common.quotation_subject, High Energy Physics::Lattice, Nuclear Theory, General Physics and Astronomy, FOS: Physical sciences, PROTON, 01 natural sciences, 7. Clean energy, Asymmetry, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Pion, DRELL-YAN PROCESS, 0103 physical sciences, 010306 general physics, NUCLEON, Nuclear Experiment, media_common, Physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Deep inelastic scattering, Deuterium, PARTON DISTRIBUTIONS, High Energy Physics::Experiment, Nucleon, BREAKING
Abstract

The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02, Comment: 7 Pages, 2 figures, RevTeX format; slight revision in text, small change in extraction of dbar-ubar and comparison with a high q2 parameterization

Published
1998
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12. Measurement of Longitudinal Spin Transfer to Lambda Hyperons in Deep Inelastic Lepton Scattering

Author

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

Subjects
Photon, HERMES, (p pi-) [mass spectrum], PROTON, 01 natural sciences, polarization [up], High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 27.5 GeV, angular distribution, deep inelastic scattering [positron p], STRUCTURE-FUNCTION G(1)(P), NUCLEON, Nuclear Experiment, Physics, BARYONS, Spin polarization, HERA, Helicity, DESY HERA Stor, polarization [Lambda], +p+pi%22">Lambda --> p pi, Quark, fragmentation [up], Nuclear and High Energy Physics, Particle physics, electroproduction [Lambda], MUON SCATTERING, FOS: Physical sciences, Nuclear physics, ASYMMETRIES, 0103 physical sciences, ddc:530, SDG 7 - Affordable and Clean Energy, 010306 general physics, Z-DECAYS, quark model parton, 010308 nuclear & particles physics, Hyperon, (LAMBDA)OVER-BAR POLARIZATION, Deep inelastic scattering, conservation law [helicity], DEUTERON, High Energy Physics::Experiment, polarized beam [positron], +Lambda%22">positron p --> Lambda, POLARIZED QUARK DISTRIBUTIONS, Lepton, experimental results
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 HERA storage ring. For an average fractional energy transfer = 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 +/- 0.17 (stat) +/- 0.03 (sys); 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., Comment: 8 pages, 3 figures; new version has an expanded discussion and small format changes

Published
2001
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