Relativistic proton-impact excitation of hydrogen atom in the presence of intense laser field

A theoretical treatment, using the first Born approximation, is presented to analyse the results of relativistic laser-assisted proton - hydrogen atom scattering. Specific calculations are carried out for excitation of hydrogen atoms from 1s_1/2 to 2s_1/2 states by proton impact. We work in an approximation in which the incoming proton may be described by Dirac-Volkov states in the presence of a laser field. Semi-relativistic Darwin wave functions are used to describe the hydrogen atom in its initial and final states, while relativistic, spin, and laser interaction effects are also accounted for. The results presented in this paper show that the differential cross section for this process depends not only upon the energy of the incident proton, but also upon its interaction with the laser field through intensity and frequency. (author)