Consequences of increased hypertriton binding for $s$-shell $\Lambda$-hypernuclear systems

TL;DR

This study investigates how increased binding energy of the hypertriton affects $s$-shell hypernuclear systems using pionless EFT, revealing shifts in resonance properties and minimal impact on other hypernuclei binding energies.

Contribution

It introduces a pionless EFT approach constrained by hypernuclear data to analyze the effects of hypertriton binding energy variations on hypernuclear states.

Findings

The $ ext{Lambda} nn$ resonance becomes broader and less observable.

The ${_{ ext{Lambda}}^3} ext{H}(rac{3}{2}^+)$ state moves closer to a bound state.

Moderate increases in hypertriton binding energy do not significantly affect ${_{ ext{Lambda}}^5} ext{He}$ binding energy.

Abstract

Consequences of increasing the binding energy of the hypertriton ground state ${_{\Lambda}^3}{\rm H}(J^P={\frac{1}{2}}^+)$ from the emulsion value $B^{\rm EMUL}_{\Lambda}({_{\Lambda}^3}{\rm H}_{\rm g.s.})$=0.13$\pm$0.05 MeV to the STAR value $B^{\rm STAR}_{\Lambda}(^{3}_{\Lambda}{\rm H}) = (0.41\pm 0.12 \pm 0.11)$ MeV are studied for $s$-shell hypernuclei within a pionless EFT approach at leading order, constrained by the binding energies of the $0^+$ and $1^+$ ${_{\Lambda}^4} {\rm H}$ states. The stochastic variational method is used in bound-state calculations, whereas the inverse analytic continuation in the coupling constant method is used to locate $S$-matrix poles of continuum states. It is found that the $\Lambda nn({\frac{1}{2}}^+)$ resonance becomes broader and less likely to be observed experimentally, whereas the ${_{\Lambda}^3}{\rm H}({\frac{3}{2}}^+)$ spin-flip virtual state moves closer to the $\Lambda d$ threshold to become a shallow bound state for specific $\Lambda N$ interaction strengths. The effect of such a near-threshold ${_{\Lambda}^3}{\rm H}({\frac{3}{2}}^+)$ state on femtoscopic studies of $\Lambda$-deuteron correlations, and its lifetime if bound, are discussed. Increasing $B_{\Lambda}({_{\Lambda}^3} {\rm H}_{\rm g.s.})$ moderately, up to $\sim$0.5 MeV, hardly affects calculated values of $B_{\Lambda}({_{\Lambda}^5}{\rm He})$.