Phys. Rev. Lett.
95,
162003
(2005)
[5 pages]
Beam-Helicity Asymmetries in Double-Charged-Pion Photoproduction on the Proton
S. Strauch et al. CLAS Collaboration
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S. Strauch1,32, B. L. Berman1, G. Adams29, P. Ambrozewicz10, M. Anghinolfi15, B. Asavapibhop21, G. Asryan38, G. Audit6, H. Avakian14,33, H. Bagdasaryan27, N. Baillie37, J. P. Ball2, N. A. Baltzell32, S. Barrow11, V. Batourine19, M. Battaglieri15, K. Beard18, I. Bedlinskiy17, M. Bektasoglu27,26, M. Bellis4, N. Benmouna1, C. Bennhold1, A. S. Biselli29,4, S. Boiarinov17,33, S. Bouchigny33,16, R. Bradford4, D. Branford9, W. J. Briscoe1, W. K. Brooks33, S. Bültmann27, V. D. Burkert33, C. Butuceanu37, J. R. Calarco24, S. L. Careccia27, D. S. Carman26, B. Carnahan5, S. Chen11, P. L. Cole33,13, A. Coleman37, P. Coltharp11, D. Cords33,*, P. Corvisiero15, D. Crabb36, H. Crannell5, J. P. Cummings29, P. V. Degtyarenko33, H. Denizli28, L. Dennis11, E. De Sanctis14, A. Deur33, R. DeVita15, K. V. Dharmawardane27, K. S. Dhuga1, C. Djalali32, G. E. Dodge27, J. Donnelly12, D. Doughty7,33, P. Dragovitsch11, M. Dugger2, S. Dytman28, O. P. Dzyubak32, H. Egiyan37,33,24, K. S. Egiyan38, L. Elouadrhiri7,33, A. Empl29, P. Eugenio11, R. Fatemi36, G. Fedotov23, G. Feldman1, R. J. Feuerbach4, A. Fix22, T. A. Forest27, H. Funsten37, G. Gavalian38,27,24, G. P. Gilfoyle31, K. L. Giovanetti18, F. X. Girod6, J. T. Goetz3, R. W. Gothe32, K. A. Griffioen37, M. Guidal16, N. Guler27, L. Guo33, V. Gyurjyan33, C. Hadjidakis16, R. S. Hakobyan5, J. Hardie7,33, D. Heddle7,33, F. W. Hersman24, K. Hicks26, I. Hleiqawi26, M. Holtrop24, J. Hu29, M. Huertas32, C. E. Hyde-Wright27, Y. Ilieva1, D. G. Ireland12, B. S. Ishkhanov23, M. M. Ito33, D. Jenkins35, H. S. Jo16, K. Joo36,8, H. G. Juengst1,27, J. D. Kellie12, M. Khandaker25, K. Y. Kim28, K. Kim19, W. Kim19, A. Klein27, F. J. Klein33,5, A. V. Klimenko27, M. Klusman29, M. Kossov17, L. H. Kramer10,33, V. Kubarovsky29, J. Kuhn4, S. E. Kuhn27, J. Lachniet4, J. M. Laget6,33, J. Langheinrich32, D. Lawrence21, T. Lee24, A. C. S. Lima1, K. Livingston12, K. Lukashin33,5, J. J. Manak33, C. Marchand6, S. McAleer11, B. McKinnon12, J. W. C. McNabb4, B. A. Mecking33, M. D. Mestayer33, C. A. Meyer4, T. Mibe26, K. Mikhailov17, R. Minehart36, M. Mirazita14, R. Miskimen21, V. Mokeev33,23, S. A. Morrow6,16, V. Muccifora14, J. Mueller28, G. S. Mutchler30, P. Nadel-Turonski1, J. Napolitano29, R. Nasseripour10,32, S. Niccolai1,16, G. Niculescu26,18, I. Niculescu1,18, B. B. Niczyporuk33, R. A. Niyazov27,33, M. Nozar33, G. V. O’Rielly1, M. Osipenko15,23, A. I. Ostrovidov11, K. Park19, E. Pasyuk2, C. Paterson9, S. A. Philips1, J. Pierce36, N. Pivnyuk17, D. Pocanic36, O. Pogorelko17, E. Polli14, S. Pozdniakov17, B. M. Preedom32, J. W. Price3, Y. Prok33,20, D. Protopopescu12, L. M. Qin27, B. A. Raue10,33, G. Riccardi11, G. Ricco15, M. Ripani15, B. G. Ritchie2, W. Roberts27, F. Ronchetti14, G. Rosner12, P. Rossi14, D. Rowntree20, P. D. Rubin31, F. Sabatié6,27, C. Salgado25, J. P. Santoro5,35, V. Sapunenko15,33, R. A. Schumacher4, V. S. Serov17, A. Shafi1, Y. G. Sharabian28,33, J. Shaw21, A. V. Skabelin20, E. S. Smith33, L. C. Smith36, D. I. Sober5, A. Stavinsky17, S. S. Stepanyan19, S. Stepanyan33,38, B. E. Stokes11, P. Stoler29, I. I. Strakovsky1, R. Suleiman20, M. Taiuti15, S. Taylor30,26, D. J. Tedeschi32, U. Thoma33,†, R. Thompson28, A. Tkabladze26,1, S. Tkachenko27, L. Todor31, C. Tur32, M. Ungaro29,8, M. F. Vineyard34,31, A. V. Vlassov17, K. Wang36, L. B. Weinstein27, D. P. Weygand33, M. Williams4, E. Wolin33, M. H. Wood32,21, A. Yegneswaran33, J. Yun27, L. Zana24, and J. Zhang27 (CLAS Collaboration)
1The George Washington University, Washington, District of Columbia 20052, 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, District of Columbia 20064, USA
6Service de Physique Nucléaire, CEA-Saclay, F91191 Gif-sur-Yvette,Cedex, France
7Christopher Newport University, Newport News, Virginia 23606, USA
8University of Connecticut, Storrs, Connecticut 06269, USA
9Edinburgh University, Edinburgh EH9 3JZ, United Kingdom
10Florida International University, Miami, Florida 33199, USA
11Florida State University, Tallahassee, Florida 32306, USA
12University of Glasgow, Glasgow G12 8QQ, United Kingdom
13Idaho State University, Pocatello, Idaho 83209, USA
14Laboratori Nazionali di Frascati, INFN, Frascati, Italy
15Sezione di Genova, INFN, 16146 Genova, Italy
16Institut de Physique Nucleaire ORSAY, Orsay, France
17Institute of Theoretical and Experimental Physics, Moscow, 117259, Russia
18James Madison University, Harrisonburg, Virginia 22807, USA
19Kyungpook National University, Daegu 702-701, South Korea
20Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
21University of Massachusetts, Amherst, Massachusetts 01003, USA
22Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
23Skobeltsyn Nuclear Physics Institute, Moscow State University, 119899 Moscow, 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
33Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
34Union College, Schenectady, New York 12308, USA
35Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0435, USA
36University of Virginia, Charlottesville, Virginia 22901, USA
37College of William and Mary, Williamsburg, Virginia 23187-8795, USA
38Yerevan Physics Institute, 375036 Yerevan, Armenia
Received 31 July 2005; published 10 October 2005
Beam-helicity asymmetries for the two-pion-photoproduction reaction γ⃗p→pπ+π- have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the behavior of this new observable.
© 2005 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.95.162003
DOI:
10.1103/PhysRevLett.95.162003
*Deceased. †Current address: Physikalisches Institut der Universität Gießen, 35392 Gießen, Germany.
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