Forward hadron production in ultraperipheral proton-heavy-ion collisions at the LHC and RHIC

We discuss hadron production in the forward rapidity region in ultraperipheral proton-lead collisions at the LHC and proton-gold collisions at RHIC. Our discussion is based on the Monte Carlo simulations of the interactions of virtual photons emitted by a fast moving nucleus with a proton beam. We simulate the virtual photon flux with the STARLIGHT event generator and then particle production with the SOPHIA, DPMJET, and PYTHIA event generators. We show the rapidity distributions of charged and neutral particles, and the momentum distributions of neutral pions and neutrons at forward rapidities. According to the Monte Carlo simulations, we find large cross sections of ultraperipheral collisions for particle production especially in the very forward region, leading to substantial background contributions to investigations of collective nuclear effects and spin physics. Finally we can distinguish between proton-nucleus inelastic interactions and ultraperipheral collisions with additional requirements of either of the charged particles at midrapidity and a certain level of activities at negative forward rapidity.