STAR Results from the RHIC Beam Energy Scan-I

TL;DR

The STAR experiment's BES Phase-I at RHIC explored a wide baryon chemical potential range, providing insights into the QCD phase diagram, phase transition signals, and critical point indications, with future plans for extended studies.

Contribution

This paper presents the first comprehensive results from RHIC's BES Phase-I, covering multiple energies and advancing understanding of QCD matter at high baryon density.

Findings

Evidence for particle production mechanisms at high baryon density

Signs of first-order phase transition and QGP 'turn-off'

Hints of a critical point in the QCD phase diagram

Abstract

The Beam Energy Scan (BES) program is being pursued at RHIC to study the QCD phase diagram, and search for the possible QCD phase boundary and possible QCD critical point. The data for Phase-I of the BES program have been collected for Au+Au collisions at center-of-mass energies ($\sqrt{s_{NN}}$) of 7.7, 11.5, 19.6, 27, and 39 GeV. These collision energies allowed the STAR experiment to cover a wide range of baryon chemical potential $\mu_{B}$ (100--400 MeV) in the QCD phase diagram. We report on several interesting results from the BES Phase-I covering the high net-baryon density region. These results shed light on particle production mechanism and freeze-out conditions, first-order phase transition and "turn-off" of QGP signatures, and existence of a critical point in the phase diagram. Finally, we give an outlook for the future BES Phase-II program and a possible fixed target program at STAR.