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High-order fluctuations of temperature in hot QCD matter

Jinhui Chen1,2,*, Wei-jie Fu3,†, Shi Yin4,‡, and Chunjian Zhang1,2,§

  • *Contact author: chenjinhui@fudan.edu.cn
  • †Contact author: wjfu@dlut.edu.cn
  • ‡Contact author: Shi.Yin@theo.physik.uni-giessen.de
  • §Contact author: chunjianzhang@fudan.edu.cn
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Phys. Rev. D 114, 014064 – Published 29 July, 2026

DOI: https://doi.org/10.1103/919p-wjfl

Abstract

A new thermodynamic state function is introduced to describe the thermodynamics relevant for the mean transverse momentum fluctuations of charged particles in heavy-ion collisions, which allows us to compute the temperature fluctuations of different orders in hot quantum chromodynamics (QCD) matter for the first time. Consequently, it is found that the temperature fluctuations are suppressed remarkably as the system transitions from the hadron resonance gas (HRG) to the quark-gluon plasma (QGP) with increasing temperature or baryon chemical potential, alongside a negative skewness. This is attributed to the general fact that the heat capacity of QCD matter increases significantly in QGP in comparison to that in HRG. These predictions provide a candidate observable to discover the thermodynamic temperature fluctuations in upcoming heavy-ion collision experiments, which also paves a novel way to study QCD thermodynamics and QCD phase diagram through measurements of the mean transverse momentum fluctuations of charged particles.

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Phys. Rev. D 114, 014064– Published 29 July, 2026
  • Received 14 April 2025
  • Revised 10 June 2026
  • Accepted 14 July 2026
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