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arXiv · 1201.2735

Evidence for the Onset of Color Transparency in $\rho^0$ Electroproduction off Nuclei

Abstract

We have measured the nuclear transparency of the incoherent diffractive $A(e,e'\rho^0)$ process in $^{12}$C and $^{56}$Fe targets relative to $^2$H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced $\rho^0$'s on a nucleus relative to deuterium, which is sensitive to $\rho A$ interaction, was studied as function of the coherence length ($l_c$), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared ($Q^2$). While the transparency for both $^{12}$C and $^{56}$Fe showed no $l_c$ dependence, a significant $Q^2$ dependence was measured, which is consistent with calculations that included the color transparency effects.

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L. El Fassi, L. Zana, K. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, X. Zheng, K. P. Adhikari, D. Adikaram, M. Aghasyan, M. J. Amaryan, M. Anghinolfi, J. Arrington, H. Avakian, H. Baghdasaryan, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, C. Bookwalter, D. Branford, W. J. Briscoe, S. Bultmann, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, P. L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, A. Daniel, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, B. Dey, R. Dickson, C. Djalali, G. E. Dodge, D. Doughty, R. Dupre, H. Egiyan, A. El Alaoui, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, M. Y. Gabrielyan, M. Garcon, N. Gevorgyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, C. Hanretty, D. Heddle, K. Hicks, R. J. Holt, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, S. S. Jawalkar, D. Keller, M. Khandaker, P. Khetarpal, A. Kim, W. Kim, A. Klein, F. J. Klein, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, V. Kuznetsov, J. M. Laget, H. Y. Lu, I. J. D. MacGregor, Y. Mao, N. Markov, M. Mayer, J. McAndrew, B. McKinnon, C. A. Meyer, T. Mineeva, M. Mirazita, V. Mokeev, B. Moreno, H. Moutarde, E. Munevar, P. Nadel-Turonski, A. Ni. 2012-01-13. Evidence for the Onset of Color Transparency in $\rho^0$ Electroproduction off Nuclei. https://doi.org/10.1016/j.physletb.2012.05.019

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