Production of the 4 ΛHe hypernucleus in Au+Au collisions at √s NN = 3 GeV with STAR

The STAR experiment reports the first measurement of the ⁴ΛHe hypernuclei yield as a function of rapidity and transverse momentum in 0–50% central Au+Au collisions at √s NN = 3 GeV. The ⁴ΛHe is reconstructed through its three-body decay channel, ⁴ΛHe → ³He + p + π⁻, with a statistical significance of about 9.5 standard deviations. We find that the yield of ⁴ΛHe as a function of rapidity is consistent with that of ⁴ΛH, and the rapidity-dependent yield ratio of ⁴ΛHe/⁴ΛH is consistent with that of ³He/t. All the measurements, as well as the transverse-momentum spectra, can be reasonably described by the JAM with a coalescence afterburner, suggesting a coalescence-based formation scenario for hyper-nuclei at this energy. The canonical thermal model reproduces the observed yield ratios but overpredicts the absolute hypernuclei yields.