Nucleon-nucleon Bremsstrahlung emission of massive axions

We consider the problem of axion production by bremsstrahlung emission in a nuclear medium. The usual assumption of a massless axion is replaced by more general hypotheses, so that we can describe the emission process for axions with mass up to a few MeV. We point out that in certain physical situations the contribution from nonzero mass is non-negligible. In particular, in the mechanism for the production of gamma ray bursts via emission of heavy axions the axion mass (ma 1 MeV) is comparable with the temperature of the nuclear medium, and thus can not be disregarded. Looking at our results we find, in fact, a fairly considerable reduction of the axion luminosity in that mechanism.