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arXiv · 2609.17328

Imprints of the nuclear liquid-gas phase transition on net-baryon number fluctuations

Mattia Recchi·Shi Yin
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Abstract

We investigate net-baryon number fluctuations in the high-density, low-temperature region of the QCD phase diagram using the parity-doublet model (PDM) under the mean-field approximation. We compute the fluctuation ratios up to sixth order around the nuclear liquid-gas (LG) phase transition, where the high-order ratios are particularly sensitive. To connect the results with heavy-ion experiments, we test several different scenarios of chemical freeze-out. We find that near the LG transition the extracted fluctuations depend strongly on the choice of freeze-out curve. We self-consistently determine four freeze-out points from preliminary results of the STAR Collaboration. Comparing the experimental data with the PDM results along these four points, we find that the model describes the low energy ($\sqrt{s_{NN}}\lesssim$ 4 GeV) data well. This suggests that nucleon interactions and the LG phase transition may contribute significantly to the fluctuations in low energy heavy-ion collisions.

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Mattia Recchi, Shi Yin. 2026-09-15. Imprints of the nuclear liquid-gas phase transition on net-baryon number fluctuations. https://arxiv.org/abs/2609.17328

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