Enhancing dark matter annihilation into neutrinos

We perform a detailed and quasi model-independent analysis of direct annihilation of dark matter into neutrinos. Considering different cases for scalar and fermionic dark matter, we identify several settings in which this annihilation is enhanced, contrary to some statements in the literature. The key point is that several restrictions of, e. g., a supersymmetric framework do not hold in general. The mass generation mechanism of the neutrinos plays an important role, too. We illustrate our considerations by two examples that are not (as usually) suppressed by the smallness of the neutrino mass, for which we also present a numerical analysis. Our results can be easily used as guidelines for model building.