In confined hadronic matter, the spontaneous breaking and restoration of chiral symmetry can be described by considering nucleons, $N_{+}(939)$, and excited states of opposite parity, $N_{-}(1535)$. In a cold, dense hadronic phase where chiral symmetry remains spontaneously broken, direct Urca decay processes involving the $N_{-}$ are possible, e.g., $N_{-}\to N_{+}+e^{-}+{\overline{\nu }}_e$. We show that at low temperature and moderate densities, because the $N_{-}$ are much heavier than the $N_{+}$, such cooling dominates over standard $N_{+}$ direct Urca processes. This provides a strong astrophysical signature of the pattern of chiral symmetry restoration in neutron stars.

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• Nuclear astrophysics
• Nuclear forces
• Nuclear matter
• Nuclear matter in neutron stars
• Quantum field theory
• Chiral symmetry