Polarization Measurements in High-Energy Deuteron Photodisintegration

K. Wijesooriya, A. Afanasev, M. Amarian, K. Aniol, S. Becher, K. Benslama, L. Bimbot, P. Bosted, E. Brash, J. Calarco, Z. Chai, C. C. Chang, T. Chang, J. P. Chen, S. Choi, E. Chudakov, S. Churchwell, D. Crovelli, S. Dieterich, S. Dumalski, D. Dutta, M. Epstein, K. Fissum, B. Fox, S. Frullani, H. Gao, J. Gao, F. Garibaldi, O. Gayou, R. Gilman, S. Glamazdin, C. Glashausser, J. Gomez, V. Gorbenko, O. Hansen, R. J. Holt, J. Hovdebo, G. M. Huber, C. W. de Jager, X. Jiang, C. Jones, M. K. Jones, J. Kelly, E. Kinney, E. Kooijman, G. Kumbartzki, M. Kuss, J. LeRose, M. Liang, R. Lindgren, N. Liyanage, S. Malov, D. J. Margaziotis, P. Markowitz, K. McCormick, D. Meekins, Z.-E. Meziani, R. Michaels, J. Mitchell, L. Morand, C. F. Perdrisat, R. Pomatsalyuk, V. Punjabi, R. D. Ransome, R. Roche, M. Rvachev, A. Saha, A. Sarty, E. C. Schulte, D. Simon, S. Strauch, R. Suleiman, L. Todor, P. E. Ulmer, G. M. Urciuoli, B. Wojtsekhowski, F. Xiong, W. Xu

We present measurements of the recoil proton polarization for the d(gamma-->,p-->)n reaction at straight theta(c.m.) = 90 degrees 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 p(y) 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(gamma,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.