Accessing chiral-even quark generalised parton distributions in the exclusive photoproduction of a γπ± pair with large invariant mass in both fixed-target and collider experiments

We compute the exclusive photoproduction of a $\gamma\,\pi^\pm$ pair using collinear factorisation framework, in kinematic regime where has large invariant mass. This channel presents new avenue for investigation GPDs. It is particularly interesting as high centre mass energies available at future experiments will allow study GPDs small skewness $ \xi $. scattering amplitude process, leading twist and order $\alpha_s$, which used to estimate its cross-section linear polarisation asymmetries with respect incoming photon, JLab~12-GeV, COMPASS, EIC LHC (in ultra-peripheral collisions) kinematics. find that magnitude estimates are sufficiently dedicated experimental analysis be performed, especially JLab. also compare results from an asymptotic distribution (DA) those recently proposed \textit{holographic} DA.