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 black triangles. Model calculations from JAM plus afterburner coalescence are shown as dash line and dotted 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. Both yield ratios given by the
JAM model plus afterburner coalescence are shown as dotted line and dotted line . Yield ratios of He4L/H4L and He3/t given by the thermal model are shown by blue and green lines, respectively.

Conclusions: