$ pi^- p rightarrow D^- Lambda_{c}^{+} $ within the Generalized Parton Picture

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 $bar{u} urightarrow bar{c} c$ 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.

Hard exclusive photoproduction of charmed mesons

{We investigate the photoproduction process $ p gamma rightarrow Lambda_{c}^{+} overline{D^{0}}$ within the handbag approach, which we assume to be the dominant mechanism at energies well above the production threshold and in the forward scattering hemisphere.

First results of proton antiproton annihilation into a pion pair at large scattering angles within the handbag approach

We propose to describe the process $ p ~ bar{p} rightarrow pi^+ ~ pi^-$ in a perturbative, QCD motivated framework in which a hard $ud , bar{u} bar{d} rightarrow d , bar{d} $ annihilation factorizes from soft transition distribution amplitudes. We advocate that the scale allowing for this factorization is the large transverse momentum transfer. In our simplified model, in which the proton is considered as a (scalar)diqark-quark system, a transition distribution amplitude describes the non-perturbative transition of the proton to the meson by emission of a scalar, isoscalar $ ud $-diquark and absorption of an antiquark (analogously for $ bar{p} rightarrow pi^- $). We model the transition distribution amplitudes as an overlap of light-cone wave functions and present first results for the differential cross section. This process will be measured by the $ bar{mbox{P}}$ANDA experiment at GSI-FAIR.