Phys. Rev. Lett.
98,
152001
(2007)
[5 pages]
Compton-Scattering Cross Section on the Proton at High Momentum Transfer
A. Danagoulian et al. Jefferson Lab Hall A Collaboration
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A. Danagoulian1, V. H. Mamyan2,3, M. Roedelbronn1, K. A. Aniol4, J. R. M. Annand5, P. Y. Bertin6, L. Bimbot7, P. Bosted8, J. R. Calarco9, A. Camsonne6, C. C. Chang10, T.-H. Chang1, J.-P. Chen3, Seonho Choi11, E. Chudakov3, P. Degtyarenko3, C. W. de Jager3, A. Deur12, D. Dutta13, K. Egiyan2,*, H. Gao13, F. Garibaldi14, O. Gayou15, R. Gilman3,16, A. Glamazdin17, C. Glashausser16, J. Gomez3, D. J. Hamilton5, J.-O. Hansen3, D. Hayes18, D. W. Higinbotham3, W. Hinton18, T. Horn10, C. Howell13, T. Hunyady18, C. E. Hyde18, X. Jiang16, M. K. Jones3, M. Khandaker19, A. Ketikyan2, V. Kubarovsky20, K. Kramer15, G. Kumbartzki16, G. Laveissière6, J. LeRose3, R. A. Lindgren12, D. J. Margaziotis4, P. Markowitz21, K. McCormick18, D. G. Meekins3, Z.-E. Meziani11, R. Michaels3, P. Moussiegt22, S. Nanda3, A. M. Nathan1, D. M. Nikolenko23, V. Nelyubin24, B. E. Norum12, K. Paschke8, L. Pentchev15, C. F. Perdrisat15, E. Piasetzky25, R. Pomatsalyuk17, V. A. Punjabi19, I. Rachek23, A. Radyushkin3,18, B. Reitz3, R. Roche26, G. Ron25, F. Sabatié18, A. Saha3, N. Savvinov10, A. Shahinyan2, Y. Shestakov23, S. Širca27, K. Slifer11, P. Solvignon11, P. Stoler20, S. Tajima13, V. Sulkosky15, L. Todor18, B. Vlahovic28, L. B. Weinstein18, K. Wang12, B. Wojtsekhowski3, H. Voskanyan2, H. Xiang27, X. Zheng27, and L. Zhu27 (Jefferson Lab Hall A Collaboration)
1University of Illinois, Urbana-Champaign, Illinois 61801, USA
2Yerevan Physics Institute, Yerevan 375036, Armenia
3Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
4California State University Los Angeles, Los Angeles, California 90032, USA
5University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
6Université Blaise Pascal/IN2P3, F-63177 Aubière, France
7IPN Orsay, Boîte Postale n1 F-91406, Orsay, France
8University of Massachusetts, Amherst, Massachusetts 01003, USA
9University of New Hampshire, Durham, New Hampshire 03824, USA
10University of Maryland, College Park, Maryland 20742, USA
11Temple University, Philadelphia, Pennsylvania 19122, USA
12University of Virginia, Charlottesville, Virginia 22901, USA
13Duke University and TUNL, Durham, North Carolina 27708, USA
14INFN, Sezione di Sanitá and Institute Superiore di Sanitá, I-00161 Rome, Italy
15College of William and Mary, Williamsburg, Virginia 23187, USA
16Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
17Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine
18Old Dominion University, Norfolk, Virginia 23529, USA
19Norfolk State University, Norfolk, Virginia 23504, USA
20Rensselaer Polytechnic Institute, Troy, New York 12180, USA
21Florida International University, Miami, Florida 33199, USA
22Institut des Sciences Nucleiares, CNRS-IN2P3, F-38016 Grenoble, France
23Budker Institute for Nuclear Physics, Novosibirsk 630090, Russia
24St. Petersburg Nuclear Physics Institute, Gatchina, 188350, Russia
25Tel Aviv University, Tel Aviv 69978, Israel
26Florida State University, Tallahassee, Florida 32306, USA
27Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
28North Carolina Central University, Durham, North Carolina 27707, USA
Received 29 January 2007; published 9 April 2007
Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s=5–11 and -t=2–7 GeV2 with a statistical accuracy of a few percent. The scaling power for the s dependence of the cross section at fixed center-of-mass angle was found to be 8.0±0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross-section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark.
© 2007 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.98.152001
DOI:
10.1103/PhysRevLett.98.152001
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