Fully correlated variational Monte Carlo study of Λ4H and Λ4H* hypernuclei

A variational Monte Carlo study of Λ4H (0+) and Λ4H∗ (1+) hypernuclear states using a realistic Hamiltonian and a fully correlated wavefunction including ΛN space-exchange correlation (SEC) is presented. For the strange sector of the Hamiltonian, phenomenological charge symmetric ΛN and ΛNN potentials are used along with Argonne NN(AV18) and Urbana NNN(UIX) potentials for the non-strange sector. Complete energy breakdown, Λ-separation energy, polarization of the nuclear core, nucleon radii (〈rp2〉1/2 and 〈rn2〉1/2) and nucleon and Λ density profiles are calculated for the Λ4H hypernuclear state. The 0+–1+ energy splitting and complete energy breakdown for 1+ excited state is also calculated. For the exact assessment of charge symmetry breaking energy, Coulomb energies for the rearranged distributions of protons in Λ4He hypernucleus are calculated. Results for all these physical observables both with and without SEC in the wavefunction are essential to extract SEC effects. Best set of variational parameters of optimized wavefunctions, both with and without SEC, are found. Dependence of results on various sets of ΛN potential strengths is investigated. This leads to some interesting results. Nucleons are pushed towards periphery as well as towards centre by the Λ hyperon which stays in the interior region most of the time. SEC effects are found to be significant. Nuclear core is found to be compact having more polarization energy with SEC in the wavefunction. (paper)