Target journal: Chinese Physics C

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Abstract:
Hypernuclei, bound states of nuclei with one or more hyperons, serve as a natural laboratory to investigate the hyperon-nucleon interaction. Hypernuclei production in heavy-ion collisions at high-baryon density region, shall provide valuable information for studying hyper-cluster formation mechanism. In Au+Au collisions at √s_NN = 3 GeV preformed by the STAR experiment, hyper-nuclei He4L are identified by its three-body decay channel, i.e He4L->3He +p+π-, and He4L yield as a function of rapidity and transverse momentum in 0-50% centrality are measured for first time. We found that yields of He4L along the rapidity are overall lower than these of H4L, and differential yield ratios of He4L/H4L are consistent with these of He3/t within uncertainties.  The observed yield ratios can be described by both the JAM plus an afterburner coalescence and canonical thermal model.

Proposed figures:

Figure 1: Rigidity (p/q) verses energy loss ⟨dE/dx⟩ obtained with the TPC detector in √s_NN = 3.0 GeV Au+Au collisions, lines represents the Bichsel functions for different particle species.


Figure 2: (Left panel) Invariant mass of He3+p+pi distributions from √s_NN = 3.0 GeV Au+Au collisions. Open circle and filled-red-circles are raw data and background subtracted distributions, respectively; (right panel) Acceptance of the He4L raw yields shown in transverse momentum p_T vs. rapidity y.


Figure 3: Transverse momentum distributions d²N/p_Tdydp_T of He4L from 0-50\% central √s_NN=3.0 GeV Au+Au collisions. Data points from four rapidity bins are shown. Blast-wave fit results are shown as dashed-lines while the JAM plus afterburner coalescence model results are shown as blue bands.


Figure 4: (Left panel) Rapidity dependence of the He4L yields (filled-black-circle) from 0-50% central √s_NN = 3.0 GeV Au+Au collisions; (right panel) Rapidity dependence of the averaged transverse momentum <p_T> of He4L. For comparison, the results of H4L are also shown as Green triangles. Model calculations from JAM plus afterburner coalescence are shown as orange- and green-lines for He4L and H4L, respectively.


Figure 5: Rapidity dependence of the yield ratio for He4L/H4L (filled circle) and He3/t (open triangle) from the 0-50% √s_NN = 3.0 GeV  Au+Au collisions. He4L/H4L yield ratio given by the JAM model plus afterburner coalescence is shown as the blue band. Yield ratios of He4L/H4L and He3/t given by the thermal model are shown by magenta and gray lines, respectively.

Conclusions: