Phys. Rev. Lett.
93,
122001
(2004)
[5 pages]
Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering at Q2=0.92 and 1.76 GeV2
G. Laveissière et al. Jefferson Lab Hall A Collaboration
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G. Laveissière1, L. Todor2, N. Degrande3, S. Jaminion1, C. Jutier1,2, R. Di Salvo1, L. Van Hoorebeke3, L. C. Alexa4, B. D. Anderson5, K. A. Aniol6, K. Arundell7, G. Audit8, L. Auerbach9, F. T. Baker10, M. Baylac8, J. Berthot1, P. Y. Bertin1, W. Bertozzi11, L. Bimbot12, W. U. Boeglin13, E. J. Brash4, V. Breton1, H. Breuer14, E. Burtin8, J. R. Calarco15, L. S. Cardman16, C. Cavata8, C.-C. Chang14, J.-P. Chen16, E. Chudakov16, E. Cisbani17, D. S. Dale18, C. W. de Jager16, R. De Leo19, A. Deur1,16, N. d'Hose8, G. E. Dodge2, J. J. Domingo16, L. Elouadrhiri16, M. B. Epstein6, L. A. Ewell14, J. M. Finn7, K. G. Fissum11, H. Fonvieille1, G. Fournier8, B. Frois8, S. Frullani17, C. Furget20, H. Gao11,21, J. Gao11, F. Garibaldi17, A. Gasparian22,18, S. Gilad11, R. Gilman23,16, A. Glamazdin24, C. Glashausser23, J. Gomez16, V. Gorbenko24, P. Grenier1, P. A. M. Guichon8, J. O. Hansen16, R. Holmes25, M. Holtrop15, C. Howell21, G. M. Huber4, C. E. Hyde-Wright2, S. Incerti9, M. Iodice17, J. Jardillier8, M. K. Jones7,16, W. Kahl25, S. Kato26, A. T. Katramatou5, J. J. Kelly14, S. Kerhoas8, A. Ketikyan27, M. Khayat5, K. Kino28, S. Kox20, L. H. Kramer13, K. S. Kumar29, G. Kumbartzki23, M. Kuss16, A. Leone30, J. J. LeRose16, M. Liang16, R. A. Lindgren31, N. Liyanage11,31, G. J. Lolos4, R. W. Lourie32, R. Madey5, K. Maeda28, S. Malov23, D. M. Manley5, C. Marchand8, D. Marchand8, D. J. Margaziotis6, P. Markowitz13, J. Marroncle8, J. Martino8, K. McCormick2,23, J. McIntyre23, S. Mehrabyan27, F. Merchez20, Z. E. Meziani9, R. Michaels16, G. W. Miller29, J. Y. Mougey20, S. K. Nanda16, D. Neyret8, E. A. J. M. Offermann16, Z. Papandreou4, B. Pasquini33, C. F. Perdrisat7, R. Perrino30, G. G. Petratos5, S. Platchkov8, R. Pomatsalyuk24, D. L. Prout5, V. A. Punjabi34, T. Pussieux8, G. Quémenér7,20, R. D. Ransome23, O. Ravel1, J. S. Real20, F. Renard8, Y. Roblin1,16, D. Rowntree11, G. Rutledge7, P. M. Rutt23, A. Saha16, T. Saito28, A. J. Sarty35, A. Serdarevic4,16, T. Smith15, G. Smirnov1, K. Soldi36, P. Sorokin24, P. A. Souder25, R. Suleiman5,11, J. A. Templon10, T. Terasawa28, R. Tieulent20, E. Tomasi-Gustaffson8, H. Tsubota28, H. Ueno26, P. E. Ulmer2, G. M. Urciuoli17, M. Vanderhaeghen37,7,16, R. Van De Vyver3, R. L. J. Van der Meer4,16, P. Vernin8, B. Vlahovic36, H. Voskanyan27, E. Voutier20, J. W. Watson5, L. B. Weinstein2, K. Wijesooriya7, R. Wilson38, B. B. Wojtsekhowski16, D. G. Zainea4, W-M. Zhang5, J. Zhao11, and Z.-L. Zhou11 (Jefferson Lab Hall A Collaboration)
1Université Blaise Pascal/IN2P3, F-63177 Aubière, France
2Old Dominion University, Norfolk, Virginia 23529, USA
3University of Gent, B-9000 Gent, Belgium
4University of Regina, Regina, Saskatchewan S4S OA2, Canada
5Kent State University, Kent, Ohio 44242, USA
6California State University, Los Angeles, California 90032, USA
7College of William and Mary, Williamsburg, Virginia 23187, USA
8CEA Saclay, F-91191 Gif-sur-Yvette, France
9Temple University, Philadelphia, Pennsylvania 19122, USA
10University of Georgia, Athens, Georgia 30602, USA
11Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
12Institut de Physique Nucléaire, F-91406 Orsay, France
13Florida International University, Miami, Florida 33199, USA
14University of Maryland, College Park, Maryland 20742, USA
15University of New Hampshire, Durham, New Hampshire 03824, USA
16Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
17INFN, Sezione Sanità and Istituto Superiore di Sanità, 00161 Rome, Italy
18University of Kentucky, Lexington, Kentucky 40506, USA
19INFN, Sezione di Bari and University of Bari, 70126 Bari, Italy
20Laboratoire de Physique Subatomique et de Cosmologie, F-38026 Grenoble, France
21Duke University, Durham, North Carolina 27706, USA
22Hampton University, Hampton, Virginia 23668, USA
23Rutgers, The State University of New Jersey, Piscataway, New Jersey 08855, USA
24Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine
25Syracuse University, Syracuse, New York 13244, USA
26Yamagata University, Yamagata 990, Japan
27Yerevan Physics Institute, Yerevan 375036, Armenia
28Tohoku University, Sendai 980, Japan
29Princeton University, Princeton, New Jersey 08544, USA
30INFN, Sezione di Lecce, 73100 Lecce, Italy
31University of Virginia, Charlottesville, Virginia 22901, USA
32State University of New York at Stony Brook, Stony Brook, New York 11794, USA
33DFNT, University of Pavia and INFN, Sezione di Pavia, ECT*, Villazzano (Trento), Italy
34Norfolk State University, Norfolk, Virginia 23504, USA
35Florida State University, Tallahassee, Florida 32306, USA
36North Carolina Central University, Durham, North Carolina 27707, USA
37Institut fuer Kernphysik, University of Mainz, D-55099 Mainz, Germany
38Harvard University, Cambridge, Massachusetts 02138, USA
Received 23 December 2003; published 14 September 2004
We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions PLL-PTT/ϵ and PLT, and the electric and magnetic generalized polarizabilities (GPs) αE(Q2) and βM(Q2) at momentum transfer Q2=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from πN intermediate states.
© 2004 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.93.122001
DOI:
10.1103/PhysRevLett.93.122001
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