Phys. Rev. Lett.
91,
222002
(2003)
[6 pages]
Measurement of the Proton Spin Structure Function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS
R. Fatemi et al. The CLAS Collaboration
Show All Authors/Affiliations
Hide All Authors/Affiliations
R. Fatemi37, A. V. Skabelin21, V. D. Burkert35, D. Crabb37, R. De Vita16, S. E. Kuhn27, R. Minehart37, G. Adams29, E. Anciant6, M. Anghinolfi16, B. Asavapibhop22, G. Audit6, T. Auger6, H. Avakian15,35, H. Bagdasaryan39, J. P. Ball2, S. Barrow12, M. Battaglieri16, K. Beard19, M. Bektasoglu27, M. Bellis29, W. Bertozzi21, N. Bianchi15, A. S. Biselli29, S. Boiarinov35, B. E. Bonner30, P. E. Bosted1, S. Bouchigny17, R. Bradford4, D. Branford10, W. K. Brooks35, C. Butuceanu38, J. R. Calarco24, D. S. Carman26, B. Carnahan5, C. Cetina13, L. Ciciani27, R. Clark4, P. L. Cole34, A. Coleman38, J. Connelly13, D. Cords35,*, P. Corvisiero16, H. Crannell5, J. P. Cummings29, E. De Sanctis15, P. V. Degtyarenko35, H. Denizli28, L. Dennis12, K. V. Dharmawardane27, K. S. Dhuga13, C. Djalali32, G. E. Dodge27, D. Doughty7, P. Dragovitsch12, M. Dugger2, S. Dytman28, M. Eckhause38, H. Egiyan38, K. S. Egiyan39, L. Elouadrhiri35, A. Empl29, P. Eugenio12, L. Farhi6, R. J. Feuerbach4, A. Freyberger35, J. Ficenec36, T. A. Forest27, V. Frolov29, H. Funsten38, S. J. Gaff9, M. Garçon6, G. Gavalian24, S. Gilad21, G. P. Gilfoyle31, K. L. Giovanetti19, P. Girard32, C. I. O. Gordon14, K. A. Griffioen38, M. Guidal17, M. Guillo32, L. Guo35, V. Gyurjyan35, C. Hadjidakis17, D. Hancock38, J. Hardie7, D. Heddle7, P. Heimberg13, F. W. Hersman24, K. Hicks26, R. S. Hicks22, M. Holtrop24, J. Hu29, C. E. Hyde-Wright27, Y. Ilieva13, M. M. Ito35, D. Jenkins36, K. Joo8, C. Keith35, J. H. Kelley9, J. D. Kellie14, M. Khandaker25, K. Y. Kim28, K. Kim20, W. Kim20, A. Klein27, F. J. Klein5, A. V. Klimenko27, M. Klusman29, M. Kossov18, V. Koubarovski29, L. H. Kramer11, Y. Kuang38, J. Kuhn29, J. Lachniet4, J. M. Laget6, D. Lawrence22, Ji Li29, K. Livingston14, A. Longhi5, K. Lukashin35, W. Major31, J. J. Manak35, C. Marchand6, S. McAleer12, J. W. C. McNabb4, B. A. Mecking35, S. Mehrabyan28, M. D. Mestayer35, C. A. Meyer4, K. Mikhailov18, M. Mirazita15, R. Miskimen22, L. Morand6, S. A. Morrow17, V. Muccifora15, J. Mueller28, G. S. Mutchler30, J. Napolitano29, R. Nasseripour11, S. O. Nelson9, S. Niccolai13, G. Niculescu26, I. Niculescu13, B. B. Niczyporuk35, R. A. Niyazov27, M. Nozar35, J. T. O’Brien5, G. V. O’Rielly13, M. Osipenko16,23, K. Park20, E. Pasyuk2, G. Peterson22, N. Pivnyuk18, D. Pocanic37, O. Pogorelko18, E. Polli15, S. Pozdniakov18, B. M. Preedom32, J. W. Price3, Y. Prok37, D. Protopopescu24, L. M. Qin27, B. A. Raue11, G. Riccardi12, G. Ricco16, M. Ripani16, B. G. Ritchie2, S. E. Rock1, F. Ronchetti15, P. Rossi15, D. Rowntree21, P. D. Rubin31, F. Sabatié6, K. Sabourov9, C. Salgado25, J. P. Santoro36, V. Sapunenko16, M. Sargsyan11, R. A. Schumacher4, M. Seely35, V. S. Serov18, Y. G. Sharabian35, J. Shaw22, S. Simionatto13, E. S. Smith35, T. Smith24, L. C. Smith37, D. I. Sober5, L. Sorrel1, M. Spraker9, A. Stavinsky18, S. Stepanyan27, P. Stoler29, S. Strauch13, M. Taiuti16, S. Taylor30, D. J. Tedeschi32, U. Thoma35, R. Thompson28, L. Todor4, C. Tur32, M. Ungaro29, M. F. Vineyard33, A. V. Vlassov18, K. Wang37, L. B. Weinstein27, H. Weller9, D. P. Weygand35, C. S. Whisnant19, E. Wolin35, M. H. Wood32, A. Yegneswaran35, J. Yun27, B. Zhang21, J. Zhao21, and Z. Zhou21 (The CLAS Collaboration)
1American University, Washington, D.C. 20016, USA
2Arizona State University, Tempe, Arizona 85287-1504, USA
3University of California at Los Angeles, Los Angeles, California 90095-1547, USA
4Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
5Catholic University of America, Washington, D.C. 20064, USA
6CEA-Saclay, Service de Physique Nucléaire, F91191 Gif-sur-Yvette, CEDEX, France
7Christopher Newport University, Newport News, Virginia 23606, USA
8University of Connecticut, Storrs, Connecticut 06269, USA
9Duke University, Durham, North Carolina 27708-0305, USA
10Edinburgh University, Edinburgh EH9 3JZ, United Kingdom
11Florida International University, Miami, Florida 33199, USA
12Florida State University, Tallahassee, Florida 32306, USA
13The George Washington University, Washington, D.C. 20052, USA
14University of Glasgow, Glasgow G12 8QQ, United Kingdom
15INFN, Laboratori Nazionali di Frascati, Frascati, Italy
16INFN, Sezione di Genova, 16146 Genova, Italy
17Institut de Physique Nucleaire ORSAY, Orsay, France
18Institute of Theoretical and Experimental Physics, Moscow, 117259, Russia
19James Madison University, Harrisonburg, Virginia 22807, USA
20Kyungpook National University, Daegu 702-701, South Korea
21Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
22University of Massachusetts, Amherst, Massachusetts 01003, USA
23Moscow State University, Moscow, 119899, Russia
24University of New Hampshire, Durham, New Hampshire 03824-3568, USA
25Norfolk State University, Norfolk, Virginia 23504, USA
26Ohio University, Athens, Ohio 45701, USA
27Old Dominion University, Norfolk, Virginia 23529, USA
28University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
29Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA
30Rice University, Houston, Texas 77005-1892, USA
31University of Richmond, Richmond, Virginia 23173, USA
32University of South Carolina, Columbia, South Carolina 29208, USA
33Union College, Schenectady, New York 12308, USA
34University of Texas at El Paso, El Paso, Texas 79968, USA
35Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
36Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0435, USA
37University of Virginia, Charlottesville, Virginia 22901, USA
38College of Willliam and Mary, Williamsburg, Virginia 23187-8795, USA
39Yerevan Physics Institute, 375036 Yerevan, Armenia
Received 16 June 2003; published 25 November 2003
Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g1(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q2=0.15–1.64 GeV2. The contributions to the first moment Γ1(Q2)=∫g1(x,Q2) dx were determined up to Q2=1.2 GeV2. Using a parametrization for g1 in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Γ1 is observed for Q2<1 GeV2, with a sign change near Q2=0.3 GeV2, indicating dominant contributions from the resonance region. At Q2=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.
© 2003 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.91.222002
DOI:
10.1103/PhysRevLett.91.222002
PACS:
13.40.Gp, 13.60.Hb, 14.20.Dh
|
|
