Double parton interactions initiated by direct photons in $\gamma p$ and $\gamma A$ collisions revisited

Abstract

We consider the double parton scattering (DPS) initiated by direct photons in $\gamma p$ and $\gamma A$ collisions. We extend the previously known results for photoproduction to the case of electroproduction with nonzero photon virtuality $Q^2$, and then consider the DPS for both photo and electroproduction for HERA and IEC ( electron ion collider) kinematics. The number of DPS events at IEC is shown to be of the same order as in HERA and is even larger, with increase in luminocity compensating the decrease of the center of mass energy.