Measurement of the ${\pi }^{-}$ decay width of ${}_{\mathrm{\Lambda }}^5$He

We have precisely measured $\mathrm{\Lambda }\to p{\pi }^{-}$ decay width of \5LHe and demonstrated significantly larger $\alpha$ -$\mathrm{\Lambda }$ overlap than expected from the central repulsion $\alpha$-$\mathrm{\Lambda }$ potential, which is derived from YNG \Lambda$-nucleon interaction.