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Abstract

The emission of a proton from a halo-nucleus by absorption of a γ-photon in the presence of a strong laser beam is studied. It is shown that the maximum value of the total cross section, when plotted as a function of the γ-photon energy, is considerably larger than those obtained from experimental data of photoproton cross sections in stable nuclei. Furthermore, the angular distribution and the energy spectrum of the emitted proton exhibit a strong dependence on field geometries, polarizations and strengths. The second project deals with the photoproduction of π⁺π⁻ pairs via multiphoton absorption from an intense x-ray laser wave colliding with an ultrarelativistic proton. By setting the pion-proton coupling constant to gσ ≈ 7.8, we reproduce the photoproduction cross section for the process γ + p → p + π⁺ + π⁻ at 440 MeV as measured with the DAPHNE detector at MAMI. With this choice, we find reasonable agreement with the experimental data in the energy range from threshold up to ≈ 480 MeV. The results was compared with other works on multiphoton μ⁺μ⁻ production. Although the muon mass is substantially smaller than the pion mass, π⁺π⁻ production is found to be dominant in the frequency range between approximately 150 and 210 MeV.