Measurement of the lifetime and $Λ$ separation energy of $^{3}_Λ\mathrm H$

Abstract

The most precise measurements to date of the $^{3}_Λ\mathrm H$ lifetime $τ$ and $Λ$ separation energy ${\rm B}_Λ$ are obtained using the data sample of Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV collected by ALICE at the LHC. The $^{3}_Λ\mathrm H$ is reconstructed via its charged two-body mesonic decay channel ($^{3}_Λ\mathrm{H} \rightarrow$ $^3$He + $π^-$ and the charge-conjugate process). The measured values $τ= [253 \pm 11 \text{ (stat.)} \pm 6 \text{ (syst.)}]$ ps and ${\rm B}_Λ= [102 \pm 63 \text{ (stat.)} \pm 67 \text{ (syst.)}]$ keV are compatible with predictions from effective field theories and confirm that the $^{3}_Λ\mathrm H$ structure is consistent with a weakly-bound system.