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Temperature derivative divergence of the electric conductivity and thermal photon emission rate at the critical end point from holography

Yi-Ping Si1,*, Danning Li2,†, and Mei Huang3,‡

  • *Contact author: siyiping23@mails.ucas.ac.cn
  • †Contact author: lidanning@jnu.edu.cn
  • ‡Contact author: huangmei@ucas.ac.cn
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Phys. Rev. D 113, 056024 – Published 25 March, 2026

DOI: https://doi.org/10.1103/l9jx-d22p

Abstract

The thermal photon emission rate dΓdk and dc electric conductivity σQ of the strongly coupled quark-gluon plasma are investigated around the critical end point in a Nf=2+1 holographic QCD model with parameters obtained from machine learning. It is found that both thermal photon emission rate and electric conductivity grow most obviously around Tc, which agrees with the previous studies, and the result of electric conductivity at zero chemical potential resembles the lattice results. Moreover, it is found that both the temperature derivative of the electric conductivity and thermal photon emission rate diverge at the critical end point.

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Phys. Rev. D 113, 056024– Published 25 March, 2026
  • Received 8 October 2025
  • Accepted 25 February 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. Funded by SCOAP3.

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