D-3(2) pairing in asymmetric nuclear matter

The superfluid D-3(2) pairing instability in isospin-asymmetric nuclear matter is studied, using the Paris nucleon-nucleon interaction as an input. It is found that the critical temperature associated with the transition to the superfluid phase becomes strongly suppressed with increasing isospin asymmetry, and vanishes for asymmetry parameter values alpha (= (n(n) - n(p))/(n(n) + n(p))) that are larger than several percent. It is shown that for neutron star models based on relativistic, field-theoretical equations of state, a large fraction of their interior may exist in a D-3(2)-paired supefluid phase. The implications of such a D-3(2) superfluid in massive neutron stars is discussed with respect to observable pulsar phenomena. Another interesting phenomenon, discussed in the paper, concerns the numerical finding of two critical superfluid temperatures for a given density in the case of isospin-asymmetric matter. Using the BCS cut-off ansatz, a mathematical expression for the critical temperature is derived which confirms this finding analytically.