Exclusive photoproduction of charmed $D^*$ vector mesons, $\gamma+N\to Y_c+ \bar{D}^*$, $Y_c=\Lambda_c^+$ or $\Sigma_c$

Abstract

The spin structure of the matrix element for the reactions $\gamma+ N\to Y_c +{D}^*$, where $Y_c=\Lambda_c^+(2285)$, $\Sigma_c(2455)$ are charmed baryons with spin 1/2, and $D^*(2010)$ is the vector charmed meson, can be parametrized, in collinear regime, in terms of three independent scalar amplitudes, which are functions of the photon energy $E_{\gamma}$, only. In framework of an effective Lagrangian approach generalized to charm photoproduction, we calculate the energy dependence of the differential cross section, the density matrix element of $\bar{D}^*$, $\rho_{11}$, the asymmetry $A_z$ in the collision of circularly polarized photons with polarized nucleons, and the polarization of the produced $Y_c$-hyperon, $P_z$, in the collision of circularly polarized photons with unpolarized target. All these polarization observables either vanish or are large, in absolute value, with a smooth $E_{\gamma}$-dependence, and differ for $\Lambda_c^+$ and $\Sigma_c$ --production.