DAPNIA-03-270 |
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Polarization phenomena in open charm photoproduction processes |
E. Tomasi-Gustafsson, M. P. Rekalo |
We analyze polarization effects in associative photoproduction of pseudoscalar ($\\overline{D}$) charmed mesons in exclusive processes $\\gamma+ N\\to Y_c +\\overline{D}$, $Y_c=\\Lambda_c^+$, $\\Sigma_c$. Circularly polarized photons induce nonzero polarization of the $Y_c$-hyperon with $x$- and $z$-components (in the reaction plane) and non vanishing asymmetries ${\\cal A}_x$ and ${\\cal A}_z$ for polarized nucleon target. These polarization observables can be predicted in model-independent way for exclusive $\\overline{D}$-production processes in collinear kinematics. The T-even $Y_c$-polarization and asymmetries for non-collinear kinematics can be calculated in framework of an effective Lagrangian approach. The depolarization coefficients $D_{ab}$, characterizing the dependence of the $Y_c$-polarization on the nucleon polarization are also calculated. |