Effects of strong magnetic fields on neutron ${}^3{P}_2$ superfluidity with spin-orbit interactions

Abstract

We discuss neutron ${}^3{P}_2$ phases in the core of neutron stars in strong magnetic field (magnetars). The neutron ${}^3{P}_2$ pairing provides a wide variety of condensates, such as the uniaxial nematic and (D${}_2$ and D${}_4$) biaxial nematic, with different symmetries stemming from the combinations of spin and momentum. Based on the spin-orbital angular momentum coupling and the spin-magnetic field coupling of the neutrons, we derive the Ginzburg-Landau equation containing higher order terms of the magnetic field. We investigate the phase diagram of the neutron ${}^3{P}_2$ superfluidity, and find that the D${}_2$ biaxial nematic phase is extended by the higher order terms of the magnetic field. We also discuss the thermodynamic properties, the heat capacity and the spin susceptibility.

Comments: Prepared for proceedings of QNP-2018, "The 8th International Conference on Quarks and Nuclear Physics" to be published in JPS Conf. Proc. Based on the original paper arXiv:1810.04901 [nucl-th]