Lifetime of the hypertriton

Abstract

We calculate the lifetime of the hypertriton as function of the $\Lambda$ separation energy $B_\Lambda$ in an effective field theory with $\Lambda$ and deuteron degrees of freedom. We also consider the impact of new measurements of the weak decay parameter of the $\Lambda$. While the sensitivity of the total width to $B_\Lambda$ is small, the partial widths for decays into individual final states and the experimentally measured ratio $R=\Gamma_{^3\textrm{He}}/\left(\Gamma_{^3 \text{He}}+\Gamma_{pd}\right)$ show a strong dependence. For the standard value $B_\Lambda=(0.13\pm 0.05)$ MeV, we find $R=0.37\pm 0.05$, which is in good agreement with past experimental studies and theoretical calculations. For the recent STAR value $B_\Lambda=(0.41\pm0.12\pm0.11)$ MeV, we obtain $R=0.57\pm 0.11$.