Variational Monte Carlo calculations for the ground- and excited-state binding energies of s-shell hypernuclei using a new form of dispersive spin-dependent noncentral $\Lambda \mathrm{NN}$ force have been made to study its effect on the overbinding problem of ${}_{\mathrm{\Lambda }}^5\mathrm{He}$ and on the spin dependence of $\Lambda N$ force. A detailed analysis shows that the strength of the dispersive $\Lambda \mathrm{NN}$ force can be adjusted to resolve the overbinding problem using two-body correlations alone. Consequently, the ambiguity in the strength of the dispersive $\Lambda \mathrm{NN}$ force masks the effect of 2π-exchange $\Lambda \mathrm{NN}$ force and $\Lambda \mathrm{NN}$ correlations on the data. The contribution of the dispersive force to the $0^{+}{-1\mathrm{}}^{+}$ spin-flip splitting of $A=4\mathrm{}$ hypernuclei is not uniquely determined. Further $B_{\Lambda }$ data favor a small spin dependence of the $\Lambda N$ potential, a situation characteristically similar to other versions of dispersive $\Lambda \mathrm{NN}$ potentials.

• Received 8 May 1998

DOI:https://doi.org/10.1103/PhysRevC.59.2807