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, 3.2, 3.5, 3.9, 4.5, and 7.7 GeV recorded by the STAR experiment.The results are compared with previous STAR measurements from the Beam Energy Scan Phase I (BES-I) and 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 where this scaling behavior breaks down at collision energies of $\sqrt{s_{NN}}$ = 3.0 and 3.2 GeV. 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 without a critical point fail to reproduce the observed trend.
