FFLO state with angle-dependent gap in asymmetric nuclear matter

We consider the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state with an angle-dependent gap (ADG) for the arbitrary angle ${\theta }_0$ between the direction of the Cooper pair momentum and the symmetry axis of the ADG in asymmetric nuclear matter. We find two kinds of locally stable states, i.e., the FFLO–ADG–orthogonal and FFLO–ADG–parallel states, which correspond to ${\theta }_0=\frac{\pi }{2}$ and ${\theta }_0=0$, respectively. Furthermore, the FFLO–ADG–orthogonal state is located at small asymmetry, whereas the FFLO–ADG–parallel state is favored for large asymmetry. The critical isospin asymmetry ${\alpha }_c$, where the superfluid vanishes, is enhanced largely by considering the Cooper pair momentum with an ADG. (paper)