Phys. Rev. C
75,
035205
(2007)
[25 pages]
First measurement of beam-recoil observables Cx and Cz in hyperon photoproduction
R. K. Bradford et al. CLAS Collaboration
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R. K. Bradford1,*, R. A. Schumacher1, G. Adams32, M. J. Amaryan30, P. Ambrozewicz13, E. Anciant7, M. Anghinolfi19, B. Asavapibhop25, G. Asryan41, G. Audit7, H. Avakian18,36, H. Bagdasaryan30, N. Baillie40, J. P. Ball3, N. A. Baltzell35, S. Barrow14, V. Batourine23, M. Battaglieri19, K. Beard22, I. Bedlinskiy21, M. Bektasoglu30, M. Bellis1, N. Benmouna15, B. L. Berman15, N. Bianchi18, A. S. Biselli12,32, B. E. Bonner33, S. Bouchigny20,36, S. Boiarinov21,36, D. Branford11, W. J. Briscoe15, W. K. Brooks36, S. Bültmann30, V. D. Burkert36, C. Butuceanu40, J. R. Calarco27, S. L. Careccia30, D. S. Carman36, B. Carnahan6, S. Chen14, P. L. Cole17,36, A. Coleman40, P. Collins3, P. Coltharp14, D. Cords36,†, P. Corvisiero19, D. Crabb39, H. Crannell6, V. Crede14, J. P. Cummings32, R. De Masi7, E. De Sanctis18, R. De Vita19, P. V. Degtyarenko36, H. Denizli31, L. Dennis14, A. Deur36, K. V. Dharmawardane30, R. Dickson1, C. Djalali35, G. E. Dodge30, J. Donnelly16, D. Doughty8,36, P. Dragovitsch14, M. Dugger3, S. Dytman31, O. P. Dzyubak35, H. Egiyan27,36,40, K. S. Egiyan41,†, L. El Fassi2, L. Elouadrhiri8,36, A. Empl32, P. Eugenio14, R. Fatemi39, G. Fedotov26, G. Feldman15, R. J. Feuerbach1,36, T. A. Forest30, H. Funsten40, M. Garçon7, G. Gavalian27,30,41, G. P. Gilfoyle34, K. L. Giovanetti22, F. X. Girod7, J. T. Goetz4, A. Gonenc13, R. W. Gothe35, K. A. Griffioen40, M. Guidal20, M. Guillo35, N. Guler30, L. Guo36, V. Gyurjyan36, C. Hadjidakis20, K. Hafidi2, H. Hakobyan41, R. S. Hakobyan6, J. Hardie8,36, D. Heddle8,36, F. W. Hersman27, K. Hicks29, I. Hleiqawi29, M. Holtrop27, J. Hu32, M. Huertas35, C. E. Hyde-Wright30, Y. Ilieva15, D. G. Ireland16, B. S. Ishkhanov26, E. L. Isupov26, M. M. Ito36, D. Jenkins38, H. S. Jo20, K. Joo9,39, H. G. Juengst30, N. Kalantarians30, J. D. Kellie16, M. Khandaker28, K. Y. Kim31, K. Kim23, W. Kim23, A. Klein30, F. J. Klein6,36, M. Klusman32, M. Kossov21, L. H. Kramer13,36, V. Kubarovsky32, J. Kuhn1, S. E. Kuhn30, S. V. Kuleshov21, J. Lachniet30, J. M. Laget7,36, J. Langheinrich35, D. Lawrence25, A. C. S. Lima15, K. Livingston16, H. Y. Lu35, K. Lukashin36, M. MacCormick20, J. J. Manak36, C. Marchand7, N. Markov9, S. McAleer14, B. McKinnon16, J. W. C. McNabb1, B. A. Mecking36, M. D. Mestayer36, C. A. Meyer1, T. Mibe29, K. Mikhailov21, M. Mirazita18, R. Miskimen25, V. Mokeev26, K. Moriya1, S. A. Morrow7,20, M. Moteabbed13, V. Muccifora18, J. Mueller31, G. S. Mutchler33, P. Nadel-Turonski15, J. Napolitano32, R. Nasseripour35, N. Natasha41, S. Niccolai15,20, G. Niculescu22,29, I. Niculescu15,22, B. B. Niczyporuk36, M. R. Niroula30, R. A. Niyazov30,36, M. Nozar36, G. V. O'Rielly15, M. Osipenko19,26, A. I. Ostrovidov14, K. Park23, E. Pasyuk3, C. Paterson16, S. A. Philips15, J. Pierce39, N. Pivnyuk21, D. Pocanic39, O. Pogorelko21, E. Polli18, I. Popa15, S. Pozdniakov21, B. M. Preedom35, J. W. Price5, Y. Prok24,39, D. Protopopescu16, L. M. Qin30, B. P. Quinn1, B. A. Raue13,36, G. Riccardi14, G. Ricco19, M. Ripani19, B. G. Ritchie3, F. Ronchetti18, G. Rosner16, P. Rossi18, D. Rowntree24, P. D. Rubin34, F. Sabatié7,30, J. Salamanca17, C. Salgado28, J. P. Santoro6,36,38, V. Sapunenko19,36, V. S. Serov21, A. Shafi15, Y. G. Sharabian36,41, J. Shaw25, N. V. Shvedunov26, S. Simionatto15,‡, A. V. Skabelin24, E. S. Smith36, L. C. Smith39, D. I. Sober6, D. Sokhan11, M. Spraker10, A. Stavinsky21, S. S. Stepanyan23, S. Stepanyan36,41, B. E. Stokes14, P. Stoler32, I. I. Strakovsky15, S. Strauch35, M. Taiuti19, S. Taylor33, D. J. Tedeschi35, U. Thoma36,§, R. Thompson31, A. Tkabladze15, S. Tkachenko30, L. Todor1, C. Tur35, M. Ungaro9,32, M. F. Vineyard34,37, A. V. Vlassov21, K. Wang39, D. P. Watts11,16, L. B. Weinstein30, H. Weller10, D. P. Weygand36, M. Williams1, E. Wolin36, M. H. Wood35, A. Yegneswaran36, J. Yun30, L. Zana27, J. Zhang30, B. Zhao9, and Z. W. Zhao35 (CLAS Collaboration)
1Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
2Argonne National Laboratory, Argonne, Illinois 60439, USA
3Arizona State University, Tempe, Arizona 85287-1504, USA
4University of California at Los Angeles, Los Angeles, California 90095-1547, USA
5California State University, Dominguez Hills, Carson, California 90747, USA
6Catholic University of America, Washington, DC 20064, USA
7CEA-Saclay, Service de Physique Nucléaire, F-91191 Gif-sur-Yvette, France
8Christopher Newport University, Newport News, Virginia 23606, USA
9University of Connecticut, Storrs, Connecticut 06269, USA
10Duke University, Durham, North Carolina 27708-0305, USA
11Edinburgh University, Edinburgh EH9 3JZ, United Kingdom
12Fairfield University, Fairfield, Connecticut 06824, USA
13Florida International University, Miami, Florida 33199, USA
14Florida State University, Tallahassee, Florida 32306, USA
15The George Washington University, Washington, DC 20052, USA
16University of Glasgow, Glasgow G12 8QQ, United Kingdom
17Idaho State University, Pocatello, Idaho 83209, USA
18INFN, Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
19INFN, Sezione di Genova, I-16146 Genova, Italy
20Institut de Physique Nucleaire ORSAY, Orsay, France
21Institute of Theoretical and Experimental Physics, Moscow, RU-117259, Russia
22James Madison University, Harrisonburg, Virginia 22807, USA
23Kyungpook National University, Daegu 702-701, South Korea
24Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
25University of Massachusetts, Amherst, Massachusetts 01003, USA
26Moscow State University, General Nuclear Physics Institute, RU-119899 Moscow, Russia
27University of New Hampshire, Durham, New Hampshire 03824-3568, USA
28Norfolk State University, Norfolk, Virginia 23504, USA
29Ohio University, Athens, Ohio 45701, USA
30Old Dominion University, Norfolk, Virginia 23529, USA
31University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
32Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA
33Rice University, Houston, Texas 77005-1892, USA
34University of Richmond, Richmond, Virginia 23173, USA
35University of South Carolina, Columbia, South Carolina 29208, USA
36Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
37Union College, Schenectady, New York 12308, USA
38Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0435, USA
39University of Virginia, Charlottesville, Virginia 22901, USA
40College of William and Mary, Williamsburg, Virginia 23187-8795, USA
41Yerevan Physics Institute, 375036 Yerevan, Armenia
Received 21 November 2006; published 21 March 2007
Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions γ⃗+p→K++Λ⃗ and γ⃗+p→K++Σ⃗0. The data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS) detector at the Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85<cosθK+c.m.<+0.95. For the Λ, the polarization transfer coefficient along the photon momentum axis, Cz, was found to be near unity for a wide range of energy and kaon production angles. The associated transverse polarization coefficient Cx is smaller than Cz by a roughly constant difference of unity. Most significantly, the total Λ polarization vector, including the induced polarization P, has magnitude consistent with unity at all measured energies and production angles when the beam is fully polarized. For the Σ0 this simple phenomenology does not hold. All existing hadrodynamic models are in poor agreement with these results.
© 2007 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevC.75.035205
DOI:
10.1103/PhysRevC.75.035205
PACS:
25.20.Lj, 13.40.-f, 13.60.Le, 14.20.Gk
*Current address: University of Rochester, Rochester, New York 14627, USA. †Deceased. ‡Current address: San Paulo University, Brazil. §Current address: Helmholtz-Institut für Strahlen-und Kernphysik, Nussallee 14-16, D-53115 Bonn, Germany.
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