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High Energy Physics - Phenomenology, hep-ph,High Energy Physics - Theory, hep-th
Abstract:
The cumulants of baryon number fluctuations serve as a good probe for
experimentally exploring the QCD phase diagram at finite density, giving rise
to characteristic fluctuation patterns associated with a possible critical
endpoint (CEP). We compute the higher-order baryon number susceptibilities at
finite temperature and baryon chemical potential using a holographic QCD model
to address the non-perturbative aspect of strongly coupled QCD matter. The
model can accurately confront lattice QCD data on a quantitative level and the
location of the CEP is found to fall within the range accessible to upcoming
experimental measurements. The baryon number susceptibilities up to the twelfth
order are computed, and the collision energy dependence of different ratios of
these susceptibilities is examined along the chemical freeze-out line. The
holographic results show quantitative agreement with experimental data and the
functional renormalization group results in a large collision energy range,
with all ratios exhibiting a peak structure around 5-10 GeV. The mismatching
between our holographic results with experimental data for sufficiently low
collision energy is possibly due to non-equilibrium effects and complex
experimental environments. The future experiments with measurements in the low
collision energy range $\sqrt{S_{NN}}\approx 1-10~\text{GeV}$ and reduced
experimental uncertainty could reveal more non-monotonic behavior signals which
can be used to locate the CEP.
