Production of light nuclei in Au+Au collisions at √s_NN = 7.7−27 GeV from STAR BES-II

¹ Institute of Particle Physics and Key Laboratory of Quark & Lepton Physics (MOE), Central China Normal University, 430079, Wuhan, China
² Physics Institute, Heidelberg University, 69120, Heidelberg, Germany

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Published online: 17 April 2026

Abstract

The studies of the production of light nuclei, such as deuteron and helium nuclei, in heavy-ion collisions are essential for understanding the dynamics of nuclear matter under extreme conditions. The yields and ratios of light nuclei serve as an effective method to distinguish between the thermal and coalescence models of light nuclei formation. Within the coalescence framework, the energy dependence of the coalescence parameters reflects the effective volume of the collision system, while in the thermal model yields are governed by chemical freeze-out conditions. The significantly larger datasets from the STAR Beam Energy Scan Phase II (BES-II), combined with enhanced detector capabilities, allow more precise and comprehensive measurements than phase I.

In these proceedings, we present measurements of light nuclei production, including p, p̅, d, d̅, ³He, in Au+Au collisions at BES-II energies of √sNN = 7.7−27 GeV. The results include centrality-dependent transverse momentum spectra and yields (dN/dy), along with coalescence parameters B_A and particle yield ratios. The physics implications of these results are discussed.