We report the triton () production in midrapidity () collisions at measured by the STAR experiment from the first phase of the beam energy scan at the Relativistic Heavy Ion Collider. The nuclear compound yield ratio (), which is predicted to be sensitive to the fluctuation of local neutron density, is observed to decrease monotonically with increasing charged-particle multiplicity () and follows a scaling behavior. The dependence of the yield ratio is compared to calculations from coalescence and thermal models. Enhancements in the yield ratios relative to the coalescence baseline are observed in the 0%-10% most central collisions at 19.6 and 27 GeV, with a significance of and , respectively, giving a combined significance of . The enhancements are not observed in peripheral collisions or model calculations without critical fluctuation, and decreases with a smaller acceptance. The physics implications of these results on the QCD phase structure and the production mechanism of light nuclei in heavy-ion collisions are discussed.
- Received 20 September 2022
- Revised 21 February 2023
- Accepted 30 March 2023
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