Variational Monte Carlo calculations ofΛ5Hehypernucleus

Abstract

We perform a realistic study of ${}_{\ensuremath{\Lambda}}^{5}\mathrm{He}$ hypernucleus using variational Monte Carlo technique. The Hamiltonian for ${}^{4}\mathrm{He}$ nuclear core of the hypernucleus is written using Argonne ${v}_{18}$ $\mathrm{NN}$ potential and Urbana model-IX $\mathrm{NNN}$ potential, where N stands for nucleon. For the strange sector, we use phenomenological $\ensuremath{\Lambda}N$ potential having central, spin, and exchange components and $\ensuremath{\Lambda}\mathrm{NN}$ potential which includes spin-dependent dispersive force and two-pion exchange force. Using this Hamiltonian and a fully correlated variational wave function, we reproduce the experimental $\ensuremath{\Lambda}$ binding energy. Without three-body $\ensuremath{\Lambda}\mathrm{NN}$ potential in the Hamiltonian and its corresponding correlation in the wave function, the hypernucleus is overbound by 0.56(4) MeV, which is about a quarter of the previous reported values of 2--3 MeV due to the use of central forces. We present the detailed energy breakdown of the hypernucleus and also show the effect of $\ensuremath{\Lambda}\mathrm{NN}$ correlation on it. The one-body density profiles for nucleon and $\ensuremath{\Lambda}$ in the hypernucleus and in its nuclear core have been critically examined. The nuclear core polarization due to presence of $\ensuremath{\Lambda}$ is precisely determined.