One meson radiative tau decays

We have studied the one meson radiative tau decays: tau- -> nu(tau) pi-(K-) gamma, computing the structure dependent contributions within a Lagrangian approach based on the large-N(C) limit of QCD that ensures the proper low-energy limit dictated by chiral symmetry. Upon imposing the short-distance QCD constraints to the form-factors we are able to predict without any free parameter the structure dependent radiation and, therefore, the relevant observables for the decay tau- -> nu(tau) pi- gamma: the photon energy spectrum, the invariant mass spectrum of the meson-photon system and the integrated decay rate. We also discuss the remaining uncertainties in these observables for the tau- -> nu(tau) K- gamma decay. According to our results, the present facilities could detect these rare decays for the first time in the near future allowing for a stringent test of our predictions.