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arXiv · 2512.03493

Precision Measurements of Kinematic Scan for Fluctuations of (Net-)proton Multiplicity Distributions in Au+Au Collisions from RHIC-STAR

Yige Huang
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Abstract

This work presents measurements of the rapidity-window dependence of event-by-event net-proton cumulants and proton factorial cumulants in Au+Au collisions at $\sqrt{s_\mathrm{NN}}=$7.7 -- 27 GeV, using high-statistics data from RHIC BES-II. Protons and antiprotons are identified with improved detector performance within $0.4<p_\mathrm{T}<2.0$ GeV/$c$ and $|y|<0.6$, enabling a wide coverage in momentum space to probe long-range correlations near the QCD critical point. In the most central collisions, the proton number $κ_2/κ_1$ and $κ_3/κ_1$ exhibit power-law scaling with the rapidity window, but with exponents below the theoretical expectation, suggesting that the critical point, if it exists, may lie at higher baryon densities. A finite-size scaling analysis of the susceptibility and Binder cumulant study points out a critical baryon chemical potential region in 550 -- 650 MeV.

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Yige Huang. 2025-12-03. Precision Measurements of Kinematic Scan for Fluctuations of (Net-)proton Multiplicity Distributions in Au+Au Collisions from RHIC-STAR. https://arxiv.org/abs/2512.03493

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