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...
Lattice QCD calculations predict the existence of a crossover between a deconfined, thermalised partonic phase and the hadronic phase under conditions of exact baryon–antibaryon symmetry. Fourth-order baryon-number susceptibilities show significant deviations from the hadron resonance gas across the crossover, carrying information on residual criticality associated with the chiral phase...
Baryon ($\mu_B$), electric charge ($\mu_Q$) and strange quark ($\mu_S$) chemical potentials, and temperature ($T$) are fundamental thermodynamic parameters characterizing QCD matter under extreme conditions. Their differentials ($\Delta\mu_B/\Delta\mu_Q$, $\Delta\mu_S/\Delta\mu_Q$) provide insight into the system’s constituent correlation, response, and trajectory in the multidimensional (4D)...
It has recently been realized that in the ultra-central heavy-ion collisions, mean transverse momentum of hadrons contains the information of the fundamental thermodynamic properties of quark-gluon plasma (QGP). In particular, in nucleus-nucleus collisions, the linear correlation between the mean transverse momentum and the charged multiplicity is attributed to the QCD speed of sound, which...
Although calculations of QCD thermodynamics from first-principle lattice simulations are limited to zero net-density due to the fermion sign problem, it is possible to extend the equation of state (EoS) to finite values of the $\mu_B, \mu_Q, \mu_S$ chemical potentials via expansions around zero chemical potentials. Thanks to a new method based on a T'-expansion scheme, it was possible to...
We present a study of net-proton number fluctuations in central Au+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 7.7 - 200$ GeV using viscous hydrodynamic simulations. Proton and antiproton fluctuations are evaluated on the hydrodynamic freeze-out hypersurface via a Cooper–Frye procedure adapted to an interacting hadron resonance gas. Effects of limited experimental acceptance and global charge...
Directed flow $v_1$ has been used to probe early dynamics in high-energy nuclear collisions. The vector meson $\phi(s \overline{s})$, with a mass comparable to that of light baryons, exhibits a small interaction cross section with other hadrons. Therefore, the measurement of $\phi$-meson directed flow $v_1$ provides clean access to the early collision dynamics and the production mechanisms of...
We explore the properties of strongly interacting matter at finite temperature and baryon chemical potential as created in relativistic heavy-ion collisions, focusing on the QCD phase structure probed via dilepton observables. The equilibrium description of the non-perturbative quark–gluon plasma (QGP) is realized within the Dynamical QuasiParticle Model (DQPM), which reproduces lattice QCD...
Recently, a new equation of state based on the two-dimensional T'-expansion scheme with a parametrizable critical point from the 3D Ising model was released [1]. It allows to produce a family of equations of state which can be used to study the effect of the critical point on the QCD phase diagram, crucial to infer its existence and location from experimental results. Employing the newly...
Measurements of identical pion femtoscopy offer insights into collision dynamics, such as collective expansion, geometry of the collision zone at freeze-out, final state interactions, etc. In addition to the quantum interference and Coulomb interactions among the pion pairs, Coulomb interactions between the pair and the net positive charge in the emitting source affect the final correlation...