Massive and massless modes of the triplet phase of neutron matter

Neutron matter at densities on the order of the nuclear saturation density is believed to have neutrons paired in the ${}^{3}P_2$ channel. We study the low-lying modes of this phase and find two massless modes (angulons), resulting from the spontaneous breaking of rotational symmetry as well as three other gapped modes. We compute their masses at arbitrary temperatures.

Figure 1

Masses of the modes associated with ${\mathcal{M}}_{(3,4)}$ in units of the magnitude of the gap at zero temperature as a function of the temperature in units of the critical temperature. The two curves represent the two poles found for a given state, and each curve corresponds to two degenerate states.

Figure 2

Magnitude of the gap as a function of temperature in units of the magnitude of the gap at zero temperature.