Diffusion of neutrinos in proto-neutron star matter with quarks

Neutrino opacities important in the evolution of a proto-neutron star conta ining quark matter are studied. The results for pure quark matter are compa red with limiting expressions previously derived, and are generalized to th e temperatures, neutrino degeneracies and lepton contents encountered in a proto-neutron star's evolution. We find that the appearance of quarks in ba ryonic matter drastically reduces the neutrino opacity for a given entropy, the reduction being sensitive to the thermodynamic conditions in the mixed quark-hadron phase. (C) 2001 Elsevier Science B.V. All rights reserved.