ACCESSING GPDs THROUGH THE EXCLUSIVE PHOTOPRODUCTION OF A PHOTON-MESON PAIR WITH A LARGE INVARIANT MASS

We study the exclusive photoproduction of a photon-meson pair with a large invariant mass, working in the QCD factorisation framework. Explicitly, we consider a rho-meson or a charged pi in the final state. This process gives access to chiral-even GPDs as well as chiral-odd GPDs. We focus here on the chiral-even sector. The computation is performed at the leading order and leading twist. We discuss the prospects of measuring them in various experiments such as the JLab 12-GeV, COMPASS, future EIC, and LHC (in ultraperipheral collisions). In particular, the high center-of-mass energies available at collider experiments can be used to probe GPDs at small skewness xi. We also compute the polarisation asymmetries with respect to the incoming photon. The results for an alternative distribution amplitude ('holographic' form) are also compared with the predictions obtained with an asymptotic distribution amplitude.

Automated summary

We study the exclusive photoproduction of a photon-meson pair with a large invariant mass in the framework of QCD factorisation. The focus is on the chiral-even sector of the generalised parton distributions (GPDs). The potential measurements of these distributions in various experiments, such as JLab 12-GeV, COMPASS, future EIC, and LHC, are discussed. The polarisation asymmetries with respect to the incoming photon are also computed.