Interplay Between Reggeon and Photon in Proton-Nucleus Collisions

In high energy collisions of proton and nucleus of charge Z ≳ 100, the Reggeon process that involves an exchange of a pair of quark and anti-quark, is subject to non-pertubative QED interaction with the electromagnetic field of the nucleus projectile, with the effective coupling constant Zα_EM ∼ $\mathcal{O}$(1). We study the interplay between non-perturbative QCD and QED in the Reggeon process of proton-nucleus collisions, using an effective theory of confined QCD strings. We find a qualitative change of large s behavior of the amplitude.