Phys. Rev. D 71, 012003 (2005) [36 pages]
Quark helicity distributions in the nucleon for up, down, and strange quarks from semi-inclusive deep-inelastic scattering
A. Airapetian et al. HERMES Collaboration
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A. Airapetian30, N. Akopov30, Z. Akopov30, M. Amarian6,30, V. V. Ammosov22, A. Andrus15, E. C. Aschenauer6, W. Augustyniak29, R. Avakian30, A. Avetissian30, E. Avetissian10, P. Bailey15, V. Baturin21, C. Baumgarten19, M. Beckmann5, S. Belostotski21, S. Bernreuther8, N. Bianchi10, H. P. Blok20,28, J. Blümlein6, H. Böttcher6, A. Borissov17, A. Borysenko10, M. Bouwhuis15, J. Brack4, A. Brüll16, V. Bryzgalov22, G. P. Capitani10, H. C. Chiang15, G. Ciullo9, M. Contalbrigo9, P. F. Dalpiaz9, R. De Leo3, L. De Nardo1, E. De Sanctis10, E. Devitsin18, P. Di Nezza10, M. Düren13, M. Ehrenfried8, A. Elalaoui-Moulay2, G. Elbakian30, F. Ellinghaus6, U. Elschenbroich12, J. Ely4, R. Fabbri9, A. Fantoni10, A. Fechtchenko7, L. Felawka26, B. Fox4, J. Franz11, S. Frullani24, G. Gapienko22, V. Gapienko22, F. Garibaldi24, K. Garrow1,25, E. Garutti20, D. Gaskell4, G. Gavrilov5,26, V. Gharibyan30, G. Graw19, O. Grebeniouk21, L. G. Greeniaus1,26, I. M. Gregor6, K. Hafidi2, M. Hartig26, D. Hasch10, D. Heesbeen20, M. Henoch8, R. Hertenberger19, W. H. A. Hesselink20,28, A. Hillenbrand8, M. Hoek13, Y. Holler5, B. Hommez12, G. Iarygin7, A. Ivanilov22, A. Izotov21, H. E. Jackson2, A. Jgoun21, R. Kaiser14, E. Kinney4, A. Kisselev21, K. Königsmann11, M. Kopytin6, V. Korotkov6, V. Kozlov18, B. Krauss8, V. G. Krivokhijine7, L. Lagamba3, L. Lapikás20, A. Laziev20,28, P. Lenisa9, P. Liebing6, T. Lindemann5, L. A. Linden-Levy15, K. Lipka6, W. Lorenzon17, J. Lu26, B. Maiheu12, N. C. R. Makins15, B. Marianski29, H. Marukyan30, F. Masoli9, V. Mexner20, N. Meyners5, O. Mikloukho21, C. A. Miller1,26, Y. Miyachi27, V. Muccifora10, A. Nagaitsev7, E. Nappi3, Y. Naryshkin21, A. Nass8, M. Negodaev6, W.-D. Nowak6, K. Oganessyan5,10, H. Ohsuga27, N. Pickert8, S. Potashov18, D. H. Potterveld2, M. Raithel8, D. Reggiani9, P. E. Reimer2, A. Reischl20, A. R. Reolon10, C. Riedl8, K. Rith8, G. Rosner14, A. Rostomyan30, L. Rubacek13, J. Rubin15, D. Ryckbosch12, Y. Salomatin22, I. Sanjiev2,21, I. Savin7, C. Scarlett17, A. Schäfer23, C. Schill11, G. Schnell6, K. P. Schüler5, A. Schwind6, J. Seele15, R. Seidl8, B. Seitz13, R. Shanidze8, C. Shearer14, T.-A. Shibata27, V. Shutov7, M. C. Simani20,28, K. Sinram5, M. Stancari9, M. Statera9, E. Steffens8, J. J. M. Steijger20, H. Stenzel13, J. Stewart6, U. Stösslein4, P. Tait8, H. Tanaka27, S. Taroian30, B. Tchuiko22, A. Terkulov18, A. Tkabladze12, A. Trzcinski29, M. Tytgat12, A. Vandenbroucke12, P. van der Nat20,28, G. van der Steenhoven20, M. C. Vetterli25,26, V. Vikhrov21, M. G. Vincter1, C. Vogel8, M. Vogt8, J. Volmer6, C. Weiskopf8, J. Wendland25,26, J. Wilbert8, G. Ybeles Smit28, S. Yen26, B. Zihlmann20, H. Zohrabian30, and P. Zupranski29 (HERMES Collaboration)
1Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1
2Physics Division, Argonne National Laboratory, Argonne, Illinois 60439-4843, USA
3Istituto Nazionale di Fisica Nucleare, Sezione di Bari, 70124 Bari, Italy
4Nuclear Physics Laboratory, University of Colorado, Boulder, Colorado 80309-0446, USA
5DESY, Deutsches Elektronen-Synchrotron, 22603 Hamburg, Germany
6DESY Zeuthen, 15738 Zeuthen, Germany
7Joint Institute for Nuclear Research, 141980 Dubna, Russia
8Physikalisches Institut, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
9Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara and Dipartimento di Fisica, Università di Ferrara, 44100 Ferrara, Italy
10Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, 00044 Frascati, Italy
11Fakultät für Physik, Universität Freiburg, 79104 Freiburg, Germany
12Department of Subatomic and Radiation Physics, University of Gent, 9000 Gent, Belgium
13Physikalisches Institut, Universität Gießen, 35392 Gießen, Germany
14Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
15Department of Physics, University of Illinois, Urbana, Illinois 61801-3080, USA
16Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
17Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120, USA
18Lebedev Physical Institute, 117924 Moscow, Russia
19Sektion Physik, Universität München, 85748 Garching, Germany
20Nationaal Instituut voor Kernfysica en Hoge-Energiefysica (NIKHEF), 1009 DB Amsterdam, The Netherlands
21Petersburg Nuclear Physics Institute, St. Petersburg, Gatchina, 188350 Russia
22Institute for High Energy Physics, Protvino, Moscow region, 142281 Russia
23Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
24Istituto Nazionale di Fisica Nucleare, Sezione Roma 1, Gruppo Sanità and Physics Laboratory, Istituto Superiore di Sanità, 00161 Roma, Italy
25Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
26TRIUMF, Vancouver, British Columbia, Canada V6T 2A3
27Department of Physics, Tokyo Institute of Technology, Tokyo 152, Japan
28Department of Physics and Astronomy, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands
29Andrzej Soltan Institute for Nuclear Studies, 00-689 Warsaw, Poland
30Yerevan Physics Institute, 375036 Yerevan, Armenia
Received 19 July 2004; published 24 January 2005
Polarized deep-inelastic scattering data on longitudinally polarized hydrogen and deuterium targets have been used to determine double-spin asymmetries of cross sections. Inclusive and semi-inclusive asymmetries for the production of positive and negative pions from hydrogen were obtained in a reanalysis of previously published data. Inclusive and semi-inclusive asymmetries for the production of negative and positive pions and kaons were measured on a polarized deuterium target. The separate helicity densities for the up and down quarks and the anti-up, anti-down, and strange sea quarks were computed from these asymmetries in a “leading order” QCD analysis. The polarization of the up-quark is positive and that of the down-quark is negative. All extracted sea quark polarizations are consistent with zero, and the light quark sea helicity densities are flavor symmetric within the experimental uncertainties. First and second moments of the extracted quark helicity densities in the measured range are consistent with fits of inclusive data.
©2005 The American Physical Society
URL: http://link.aps.org/doi/10.1103/PhysRevD.71.012003
DOI: 10.1103/PhysRevD.71.012003
PACS: 13.60.–r, 13.88.+e, 14.20.Dh, 14.65.–q
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