Production of a pion in association with a high-Q2 dilepton pair in antiproton-proton annihilation at GSI-FAIR

We evaluate the cross section for (p) over barp -> l(+) l(-) pi(0) in the forward direction and for a large lepton pair invariant mass. In this kinematical region, the leading-twist amplitude factorizes into a short-distance matrix element, long-distance antiproton-distribution amplitudes, and proton to pion transition distribution amplitudes (TDAs). Using a modeling inspired from the chiral limit for these TDAs, we obtain a first estimate of this cross section, which demonstrates that this process can be measured at GSI-FAIR.