First order phase transitions in neutron star matter: droplets and coherent neutrino scattering

A first order phase transition at high baryon density implies that a mixed phase can occupy a significant region of the interior of a neutron star. In this article, we investigate the effect of a droplet phase on neutrino tra nsport inside the core. Two specific scenarios of the phase transition, one having a kaon condensate and the other having quark matter in the high den sity phase, are examined. The coherent scattering of neutrinos off the drop lets greatly increases the neutrino opacity of the mixed phase. We comment on how the existence of such a phase will affect a supernova neutrino signa l. (C) 2000 Elsevier Science B.V. All rights reserved.