Measurement of the lifetime and $\mathrm{\Lambda }$ separation energy of ${}_{\mathrm{\Lambda }}^3\mathrm{H}$

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