Speaker
Description
We report the first measurements of two-particle transverse momentum correlations for mid-rapidity charged particles in Au+Au collisions at $\sqrt{s_{\rm NN}} =$ 3.0–7.7 GeV recorded by the STAR experiment from the Beam Energy Scan Phase-II (BES-II). The results are compared with previous STAR measurements from BES-Iand with transport model calculations. The measured two-particle $p_{\rm T}$ correlators exhibit an approximate power-law scaling with the number of participating nucleons ($N_{\text{part}}$), consistent with expectations from an independent-source scenario. For the first time, we identify a collision-energy region in which this scaling behavior breaks down, most notably at $\sqrt{s_{\rm NN}} = 3.0$ GeV, where the system is hadronic-dominated and the independent-source picture is expected to fail. Furthermore, a non-monotonic energy dependence of the $p_{\rm T}$ correlations is observed in central collisions, representing the first systematic observation of such behavior as a function of collision energy. Transport model calculations that do not include critical dynamics fail to reproduce the observed trend.
| Is the talk given on behalf of the Collaboration? | yes |
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| Topic area | Critical Point |