Thermodynamics of $n$-$p$ condensate in asymmetric nuclear matter

Abstract

We study the neutron-proton pairing in nuclear matter as a function of isospin asymmetry at finite temperatures and the saturation density using realistic nuclear forces and Brueckner-renormalized single particle spectra. Our computation of the thermodynamic quantities shows that while the difference of the entropies of the superconducting and normal phases anomalously changes its sign as a function of temperature for arbitrary asymmetry, the grand canonical potential does not; the superconducting state is found to be stable in the whole temperature-asymmetry plane. The pairing gap completely disappears for density-asymmetries exceeding ${\alpha }_c=(n_n-n_p)/n\simeq 0.11$.

Comments: 7 pages, including 3 figures, uses revtex