Nuclear Modification Factor of Inclusive Charged Particles in Au+Au Collisions at Snn = 19.6 and 27 GeV with the STAR Experiment

The Quantum Chromodynamics (QCD) phase diagram, characterized by temperature (T) and baryon chemical potential (mu(B)), features a transition from hadronic matter to a deconfined Quark Gluon Plasma (QGP) at certain values of T and mu(B). The Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider (RHIC) explores this phase structure by sys-tematically varying the collision energy of Au+ Au collisions, with a key focus on locating the QCD phase boundary and the critical point. During the first phase (BES-I, 2010 2014), STAR experiment measured the nuclear modifica tion factor (R-cp) of inclusive charged particles in Au + Au collisions in the energy range from root(NN)-N-S 7.7 to 39 GeV. In 2018, the STAR experiment initiated the second phase of the BES program (BES-II), which has a tenfold increase in statistics compared to the first phase. This enables better precision Rer measurements. By 2018 2019, STAR collected more than 500 million Au + Au events at root(NN)-N-S 19.6 and 27 GeV, two orders of magnitude larger than the BES-I dataset at these energies. In these proceedings, we present new measurements of charged-particle production and R-CP measurements on the high-statistics BES-II data at root(NN)-N-S 19.6 and 27 GeV, comparing them with BES-I results. We further evaluate theoretical expectations using UrQMD and hydrody-namic (SMASH + VHLLE) model predictions, testing their description of the experimental observations. By extending the analysis to higher transverse momenta (p(T)), we probe potential jet quenching effects and assess implications for QGP formation and properties at lower collision encrrics