GaGaRes: A Monte Carlo generator for resonance production in two-photon physics

In this paper a Monte Carlo generator, GaGaRes, is presented which can be used to describe two-photon resonance production in e^+e^- collisions. The program can generate the five lowest-lying C=+1 meson states of any q\bar{q} combination together with the outgoing electron and positron. The dependence on the photon virtualities Q_1^2 and Q_2^2 is fully taken into account. The program also generates the density matrices of the resonance, which form an essential tool in the description of the decay of the resonances. Furthermore, the program is applicable for all tagging conditions.