Ground state of stressed two-flavor quark matter

Determine whether stressed two-flavor quark matter in neutron-star cores realizes conventional 2SC, a gapless or crystalline phase, or a phase with secondary pairing of nominally unpaired quarks, and establish whether the realized phase is a superfluid.

Background

Strange-quark mass effects, beta equilibrium, and electric and color neutrality create Fermi-surface mismatches that may destabilize ideal 2SC pairing. The resulting phase determines whether rotational vortices exist in the quark core.

References

It remains unclear whether the resulting state is conventional 2SC, a gapless or crystalline phase, or a phase with secondary pairing of the nominally unpaired quarks.

— Superfluidity and Vortex Dynamics in Neutron Stars  (2609.01022 - Link et al., 1 Sep 2026) in Section “Open questions and perspectives” under “Quantum vorticity in quark matter”