Exclusive photoproduction of charmed $D^{\ast }$ vector mesons, $\gamma +N\to Y_c+{\bar{D}}^{\ast }$, $Y_c={\Lambda }_c^{+}$ or ${\Sigma }_c$

Abstract

The spin structure of the matrix element for the reactions $\gamma +N\to Y_c+D^{\ast }$, where $Y_c={\Lambda }_c^{+}(2285)$, ${\Sigma }_c(2455)$ are charmed baryons with spin 1/2, and $D^{\ast }(2010)$ 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 ${\bar{D}}^{\ast }$, ${\rho }_{11}$, 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.

Comments: 15 pages, 4 figures