Phys. Rev. Lett.
86,
2975–2979
(2001)
Polarization Measurements in High-Energy Deuteron Photodisintegration
K. Wijesooriya et al. (Jefferson Lab Hall A Collaboration)
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K. Wijesooriya10,*, A. Afanasev20,26, M. Amarian11, K. Aniol3, S. Becher9, K. Benslama23, L. Bimbot22, P. Bosted16, E. Brash23, J. Calarco18, Z. Chai17, C. C. Chang15, T. Chang10, J. P. Chen26, S. Choi25, E. Chudakov26, S. Churchwell6, D. Crovelli24, S. Dieterich24, S. Dumalski23, D. Dutta17, M. Epstein3, K. Fissum14, B. Fox4, S. Frullani11, H. Gao17, J. Gao2, F. Garibaldi11, O. Gayou1,28, R. Gilman24,26,†, S. Glamazdin13, C. Glashausser24, J. Gomez26, V. Gorbenko13, O. Hansen26, R. J. Holt10,‡, J. Hovdebo23, G. M. Huber23, C. W. de Jager26, X. Jiang24, C. Jones2, M. K. Jones21, J. Kelly15, E. Kinney4, E. Kooijman12, G. Kumbartzki24, M. Kuss26, J. LeRose26, M. Liang26, R. Lindgren27, N. Liyanage26, S. Malov24, D. J. Margaziotis3, P. Markowitz7, K. McCormick5, D. Meekins8, Z.-E. Meziani25, R. Michaels26, J. Mitchell26, L. Morand24, C. F. Perdrisat28, R. Pomatsalyuk13, V. Punjabi19, R. D. Ransome24, R. Roche8, M. Rvachev17, A. Saha26, A. Sarty8,§, E. C. Schulte10, D. Simon9, S. Strauch24, R. Suleiman12, L. Todor21, P. E. Ulmer21, G. M. Urciuoli11, B. Wojtsekhowski26, F. Xiong17, and W. Xu17 (Jefferson Lab Hall A Collaboration)
1Université Blaise Pascal/IN2P3, F-63177 Aubière, France
2California Institute of Technology, Pasadena, California 91125
3California State University, Los Angeles, California 90032
4University of Colorado, CB 446, Boulder, Colorado 80309
5DAPNIA, Saclay, France
6Duke University, Durham, North Carolina 27706
7Florida International University, Miami, Florida 33199
8Florida State University, Tallahassee, Florida 32306
9University of Georgia, Athens, Georgia 30602
10University of Illinois, Urbana-Champaign, Illinois 61801
11INFN, Sezione Sanitá and Istituto Superiore di Sanitá, Laboratorio di Fisica, I-00161 Rome, Italy
12Kent State University, Kent, Ohio 44242
13Kharkov Institute of Physics and Technology, Kharkov 310108, Ukraine
14University of Lund, P.O. Box 118, S-221 00 Lund, Sweden
15University of Maryland, College Park, Maryland 20742
16University of Massachusetts, Amherst, Massachusetts 01003
17Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
18University of New Hampshire, Durham, New Hampshire 03824
19Norfolk State University, Norfolk, Virginia 23504
20North Carolina Central University, Durham, North Carolina 27707
21Old Dominion University, Norfolk, Virginia 23529
22Institut de Physique Nucléaire, F-91406 Orsay, France
23University of Regina, Regina, Saskatchewan, Canada S4S 0A2
24Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
25Temple University, Philadelphia, Pennsylvania 19122
26Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606
27University of Virginia, Charlottesville, Virginia 22901
28College of William and Mary, Williamsburg, Virginia 23187
Received 15 September 2000; revised 19 December 2000; published in the issue dated 2 April 2001
We present measurements of the recoil proton polarization for the d(γ⃗,p⃗)n reaction at θc.m. = 90° for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(γ,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.
© 2001 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.86.2975
DOI:
10.1103/PhysRevLett.86.2975
PACS:
25.20.-x, 24.70.+s, 24.85.+p, 25.10.+s
*Present address: Argonne National Laboratory, Argonne, IL 60439. †Corresponding author. Email address: gilman@jlab.org ‡ §Present address: St. Mary's University, Halifax, Nova Scotia, Canada B3H 3C3.
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