$ π^- p \rightarrow D^- Λ_{c}^{+} $ within the Generalized Parton Picture

Abstract: We investigate the reaction $ \pi^- p \rightarrow D^- \Lambda_{c}^{+} $ within the generalized parton picture. The process is described by a handbag-type mechanism with the charm-quark mass acting as the hard scale. As in the case of preceding work on $\bar{p} p \rightarrow \bar{\Lambda}^-_c \Lambda_{c}^{+} $ we argue that the process amplitude factorizes into one for the perturbatively calculable partonic subprocess $\bar{u} u\rightarrow \bar{c} c$ and hadronic matrix elements that can be parameterized in terms of generalized parton distributions. Modeling the generalized parton distributions by overlaps of (valence-quark) light-cone wave functions for the hadrons involved, we obtain numerical results for unpolarized differential and integrated cross sections as well as spin observables. Our approach works well above the production threshold ($s \gtrsim 20 $GeV$^2$) in the forward hemisphere and predicts unpolarized cross sections of the order of nb, a finding that could be of interest in view of plans to measure $ \pi^- p \rightarrow D^- \Lambda_{c}^{+} $ at J-PARC.