The acceleration of electrons by very intense lasers in vacuum is studied for different forms of laser pulses: finite plane and three-dimensional laser pulses. The latter case is treated by introducing an approximation of the laser frequency as a function of the Cartesian components of the wave number. Various examples which lead to high accelerations of electrons are given.

Pion production by antiproton annihilation on neutron-or proton-rich nuclei is studied in a fully quantum mechanical description of the reaction process in terms of a distorted wave approach. The elementary elastic NN and the NN → nπ annihilation vertices are obtained from a t-matrix accounting for coupled channels effects. The theoretical amplitudes are used to derive a microscopic N A optical model potential and the meson production vertices. Nuclear structure effects are taken into account microscopically. Results for meson production cross sections are presented.

Abstract. Pion production in coherent antiproton annihilation reactions on nuclei is studied in a fully quantum mechanical description. The elementary elastic NN and the NN → nπ annihilation vertices are obtained from a t-matrix accounting for coupled channels effects. The theoretical amplitudes are used to derive a microscopic NA optical model potential and the meson production vertices. Pion nucleus final state interaction are taken into account by adding higher pion-nucleon resonances beyond the ∆-resonance. Nuclear structure aspects are described by HFB-theory. Results for pA, πA and meson production cross sections are presented.

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