Laser-assisted radiative recombination beyond the dipole approximation

A comprehensive theoretical approach to describe the electron-ion radiative recombination in the presence of intense, short laser pulses, which accounts for $1/c$ corrections, is presented. Its essential step is based on expanding the relativistic Coulomb-Volkov solution describing an electron in a combined Coulomb potential and a laser field in powers of $1/c$. In this way, we can trace the origin of nondipole effects observed in the spectrum of emitted radiation. Hence, as we demonstrate for high-frequency pulses assisting the process, a significant extension of the cutoff and asymmetry in angular distributions of the emitted radiation can be attributed to the electron recoil off the laser pulse. In addition, we investigate the possibility of enhancing the efficiency of the generated high-energy radiation by chirping the pulse.