Impact of spin-isospin fluctuations on single-particle degrees of freedom in dense neutron matter

The Fermi surface of dense neutron matter may experience a rearrangement ne ar the onset of pion condensation, due to a strong momentum dependence of t he effective interaction by spin-isospin fluctuations. For example, a secon d (inner) Fermi surface may arise as high-momentum single-particle stares a re filled and low-momentum states are vacated. The influence of this phenom enon on the superfluid-transition temperature is investigated with the aid of a separation transformation of the BCS gap equation. Attention is also g iven to modifications of the specific-heat discontinuity at the transition temperature and the relation between the transition temperature and the zer o-temperature energy gap. (C) 2001 MAIK "Nauka/lnterperiodica".