Lifetime of the hypertriton

TL;DR

This paper calculates the hypertriton lifetime as a function of the $ ext{Lambda}$ separation energy using effective field theory, analyzing how new measurements influence decay widths and ratios, with results aligning with experimental data.

Contribution

It introduces a detailed calculation of hypertriton lifetime dependence on $ ext{Lambda}$ separation energy within an effective field theory framework, considering recent experimental updates.

Findings

Partial decay widths depend strongly on $B_\Lambda$

The ratio $R$ varies with $B_\Lambda$, matching experimental values

Calculated $R$ agrees with past data for standard $B_\Lambda$

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 $R=0.57\pm 0.11$.