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| Autor principal: | |
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| Formato: | Preprint |
| Publicado: |
2025
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| Materias: | |
| Acceso en línea: | https://arxiv.org/abs/2504.00817 |
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| _version_ | 1866912303808512000 |
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| author | The STAR Collaboration |
| author_facet | The STAR Collaboration |
| contents | We report precision measurements on cumulants ($C_{n}$) and factorial cumulants ($κ_{n}$) of (net-)proton number distributions up to fourth-order in Au+Au collisions from phase II of the Beam Energy Scan program at RHIC. (Anti-)protons are selected at midrapidity ($|y|<0.5$) within a transverse momentum range of $0.4 < p_T < 2.0$ GeV/$c$. The collision energy and centrality dependence of these cumulants are studied over center-of-mass energies $\sqrt{s_{NN}}$ = 7.7 -- 27 GeV. Relative to various non-critical-point model calculations and peripheral collision 70-80\% data, the net-proton $C_4/C_2$ measurement in 0-5\% collisions shows a minimum around 19.6 GeV for significance of deviation at $\sim2$ -- $5σ$. In addition, deviations from non-critical baselines around the same collision energy region are also seen in proton factorial cumulant ratios, especially in $κ_2/κ_1$ and $κ_3/κ_1$. Dynamical model calculations including a critical point are called for in order to understand these precision measurements. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_00817 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Precision Measurement of (Net-)proton Number Fluctuations in Au+Au Collisions at RHIC The STAR Collaboration Nuclear Experiment We report precision measurements on cumulants ($C_{n}$) and factorial cumulants ($κ_{n}$) of (net-)proton number distributions up to fourth-order in Au+Au collisions from phase II of the Beam Energy Scan program at RHIC. (Anti-)protons are selected at midrapidity ($|y|<0.5$) within a transverse momentum range of $0.4 < p_T < 2.0$ GeV/$c$. The collision energy and centrality dependence of these cumulants are studied over center-of-mass energies $\sqrt{s_{NN}}$ = 7.7 -- 27 GeV. Relative to various non-critical-point model calculations and peripheral collision 70-80\% data, the net-proton $C_4/C_2$ measurement in 0-5\% collisions shows a minimum around 19.6 GeV for significance of deviation at $\sim2$ -- $5σ$. In addition, deviations from non-critical baselines around the same collision energy region are also seen in proton factorial cumulant ratios, especially in $κ_2/κ_1$ and $κ_3/κ_1$. Dynamical model calculations including a critical point are called for in order to understand these precision measurements. |
| title | Precision Measurement of (Net-)proton Number Fluctuations in Au+Au Collisions at RHIC |
| topic | Nuclear Experiment |
| url | https://arxiv.org/abs/2504.00817 |