RPA response functions in neutron matter and their effect on pairing
ABSTRACT :
Uniform neutron matter can serve as a simplified model for the unbound neutrons in the inner crust of neutron stars. Its superfluidity has important consequences for astrophysical observables such as neutron-star cooling and pulsar glitches. But the pairing gap and critical temperature are not well known. The largest theoretical uncertainty comes probably from the medium polarization (screening) effects, in particular from the strong cancellations between the exchange of spin and density fluctuations. Using the framework of phenomenological Skyrme energy-density functionals, I will discuss the response functions in the spin and density channels within the random-phase approximation (RPA). These response functions are then used to compute the screened pairing interaction. The results indicate that the medium polarization effects reduce the critical temperature at all relevant densities, in contrast to what was found previously within the widely used Landau approximation.