Continuity from neutron matter to color-superconducting quark matter with $^3 P_2$ superfluidity

I clarify how the concept of quark-hadron continuity, which was previously considered in the context of the asymptotic color-flavor locked phase with ideal three-flavor symmetry, is applied to two-flavor matter. Our observation is that neutron star matter can continuously be connected to two-flavor color-superconducting (2SC) phase with an additional condensate of $d$-quarks in the $^3P_2$ channel. I discuss here two aspects of this novel phase. First, I introduce the notion of continuity based on the patterns of symmetry breaking and the corresponding order parameters, and then explain qualitatively the physics mechanism of $d$-quark $^3P_2$ pairing in analogy to nuclear physics. Our finding serves as the theoretical underpinning for the phenomenological construction of the equation of state in the neutron star environment.