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QCD matter at a finite magnetic field and nonzero chemical potential

Zhi-Ying Qin1,2, Bo Feng1, Ya-Hui Hou1, Hong-Yue Song1, Wen-Chao Zhang1,*, Hua Zheng1, and Shi-Jun Mao3

  • *Contact author: wenchao.zhang@snnu.edu.cn
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Phys. Rev. D 114, 016028 – Published 27 July, 2026

DOI: https://doi.org/10.1103/r8b2-3bnp

Abstract

We construct a hybrid equation of state (EoS) by smoothly interpolating the EoS in the hadron resonance gas at low temperatures to that in the ideal parton gas at high temperatures, and employ it to study the properties of the quantum chromodynamics (QCD) matter under a finite magnetic field and nonzero chemical potential. In this work, we neglect the anomalous magnetic moment effects of both charged and neutral particles. Our results show that the thermodynamic observables such as the entropy density, the pressure, the energy density, the trace anomaly, and the specific heat at constant volume are sensitive to both the finite magnetic field and chemical potential. As the chemical potential increases from zero, these quantities rise in both the hadronic and quark-gluon plasma phases. In contrast, introducing a magnetic field suppresses them at low temperatures but enhances them at high temperatures. Furthermore, nonzero chemical potential and magnetic field introduce nontrivial modifications to the squared speed of sound. Both effects increase its value near the critical temperature while reducing it at lower temperatures. When both the chemical potential and the magnetic field are present, their influences superimpose, leading to more intricate changes in the thermodynamic behavior. Finally, we compare our results with the lattice QCD data for the quadratic fluctuations of conserved charges and their correlations. The model successfully reproduces the temperature dependence of these observables at eB=0 and 0.04  GeV2. However, at the stronger field strength eB=0.14  GeV2, the model underestimates the magnitudes while still capturing the overall temperature trend.

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Phys. Rev. D 114, 016028– Published 27 July, 2026
  • Received 12 February 2026
  • Accepted 6 July 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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