Measurement of ${}_{\hat{\mathrm{I}}}^4›\mathrm{H}$ and ${}_{\hat{\mathrm{I}}}^4›\mathrm{He}$ binding energy in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV

Abstract

Measurements of mass and $\hat{I}›$ binding energy of ${}_{\hat{\mathrm{I}}}^4›\mathrm{H}$ and ${}_{\hat{\mathrm{I}}}^4›\mathrm{He}$ in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=3$ GeV are presented, with an aim to address the charge symmetry breaking (CSB) problem in hypernuclei systems with atomic number A = 4. The $\hat{I}›$ binding energies are measured to be $2.22\pm 0.06(stat.)\pm 0.14(syst.)$ MeV and $2.38\pm 0.13(stat.)\pm 0.12(syst.)$ MeV for ${}_{\hat{\mathrm{I}}}^4›\mathrm{H}$ and ${}_{\hat{\mathrm{I}}}^4›\mathrm{He}$, respectively. The measured $\hat{I}›$ binding-energy difference is $0.16\pm 0.14(stat.)\pm 0.10(syst.)$ MeV for ground states. Combined with the ${\hat{I}}^3$-ray transition energies, the binding-energy difference for excited states is $-0.16\pm 0.14(stat.)\pm 0.10(syst.)$ MeV, which is negative and comparable to the value of the ground states within uncertainties. These new measurements on the $\hat{I}›$ binding-energy difference in A = 4 hypernuclei systems are consistent with the theoretical calculations that result in $\hat{\mathrm{I}}”{\mathrm{B}}_{\hat{\mathrm{I}}}{›}^4(1_{\mathrm{exc}}^{+})\approx -\hat{\mathrm{I}}”{\mathrm{B}}_{\hat{\mathrm{I}}}{›}^4(0_{g.s.}^{+})<0$ and present a new method for the study of CSB effect using relativistic heavy-ion collisions.

8 pages, 5 figures