Proton cumulants from hydrodynamics in light of new STAR data

Abstract

New measurements of proton number cumulants from the Beam Energy Scan Phase II (BES-II) program at RHIC by the STAR Collaboration provide unprecedented precision and insights into the properties of strongly interacting matter. This report discusses the measurements in the context of predictions from hydrodynamics, emphasizing the enhanced sensitivity of factorial cumulants and their implications for the search for the QCD critical point. The experimental data shows enhancement of second-order factorial cumulants and suppression of third-order factorial cumulants relative to the non-critical baseline at $7.7 < \sqrt{s_{\rm NN}} \lesssim 10$ GeV. We discuss implications of this observation for the possible location of the critical point in the QCD phase diagram and opportunities for future measurements of acceptance dependence of factorial cumulants.