Light nuclei in supernova envelopes: a quasiparticle gas model

We present an equation of state and the composition of low-density supernova matter composed of light nuclei with mass number A \le 13. We work within the quasiparticle gas model, which accounts for bound states with decay time scales larger than the relevant time scale of supernova and protoneutron star evolution. The mean-field contribution is included in terms of Skyrme density functional. Deuterons, tritons, and 3H(e) nuclei appear in matter in concentrations that are substantially higher than those of heavier nuclei. We calculate the critical temperature of deuteron condensation in such matter, and demonstrate that the appearance of clusters substantially lowers the critical temperature.