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Neutrino absorption in two-flavor color-superconducting quark matter

M. G. Alford1,*, L. Brodie1,†, M. Buballa2,3,‡, H. Gholami2,§, A. Haber1,4,∥, and M. Hofmann1,2,¶

  • *Contact author: alford@physics.wustl.edu
  • †Contact author: b.liam@wustl.edu
  • ‡Contact author: michael.buballa@tu-darmstadt.de
  • §Contact author: mohammadhossein.gholami@tu-darmstadt.de
  • ∥Contact author: a.haber@soton.ac.uk
  • Contact author: marco.hofmann.physics@protonmail.com
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Phys. Rev. C 114, 055801 – Published 2 November, 2026

DOI: https://doi.org/10.1103/dg6d-6cv3

Abstract

We calculate the absorption mean free paths of electron and muon neutrinos in two-flavor color-superconducting (2SC) quark matter in the density and temperature range that is relevant to binary neutron star mergers. We model the strong interaction between quarks using a Nambu–Jona-Lasinio model, performing calculations self-consistently in the mean-field approximation. Since the 2SC gap is large we restrict our analysis to the contribution of unpaired quarks. We find that at low temperatures absorption by a down quark ν+d→u+e−/μ− is kinematically not allowed, so absorption by a strange quark, ν+s→u+e−/μ−, dominates the mean free path. As temperature or neutrino energy rises, the d quark absorption channel becomes active, and the mean free path shrinks. We find that in equilibrated 2SC matter with an electron lepton fraction YLe=0.1, the neutrinos form a degenerate gas with a mean free path of meters or less, independently of the temperature.

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Phys. Rev. C 114, 055801– Published 2 November, 2026
  • Received 4 November 2025
  • Accepted 20 August 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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