  We investigate the intense X-ray laser-induced proton emission from halo
nuclei within the framework of a nonperturbative quantum $S$-matrix approach.
We have analytically deduced the angular differential as well as the total
multi-photon rates of the proton emissions. For a linearly polarized X-ray
laser field, we find that the angular distributions of proton emission
sensitively depend on the laser frequency and show an interesting petal
structure with increasing the laser frequency as well as the number of absorbed
photons. Meanwhile, we find the Coulomb repulsion potential between the proton
and the remainder nucleus has a strong hindering effect on the total
multi-photon rates of the proton emissions and leads to the blue shifts of the
multi-photon transition frequency. Moreover, the polarization effects of laser
fields on total rates of proton emission have also been addressed. We find that
the polarized ellipticity corresponding to the maximum of the total rates
depend on the laser frequency showing a transition from perturbative to
nonperturbative proton emission. The underlying mechanism of the above findings
is uncovered, and some implications are discussed.
