FRESH LOOK AT AXIONS AND SN 1987A

We reexamine the very stringent limit on the axion mass based on the s trength and duration of the neutrino signal from SN 1987A, in the ligh t of new measurements of the axial-vector coupling strength of nucleon s, possible suppression of axion emission due to many-body effects, an d additional emission processes involving pions. The suppression of ax ion emission due to nucleon spin fluctuations induced by many-body eff ects degrades previous limits by a factor of about 2. Emission process es involving thermal pions can strengthen the limits by a factor of 3- 4 within a perturbative treatment that neglects saturation of nucleon spin fluctuations. Inclusion of saturation effects, however, tends to make the limits less dependent on pion abundances. The resulting upper limit to the axion mass also depends on the precise couplings of the axion and ranges from 0.5 x 10(-3) eV to 6 x 10(-3) eV, consistent wit h previous results.