Results are reported on precise measurements of the weak-decay processes of 4ΛH and 4ΛHe hypernuclei formed via the 4He(K-stopped, π-) reaction. The lifetimes of 4ΛH (194+24-26 ps) and 4ΛHe (256 ± 27 ps) were obtained. The π0 and π- decay branching ratios of 4ΛHe (0.515 ± 0.035 and 0.322 ± 0.034, respectively) were precisely determined and they are compared with recent theoretical estimates and related experimental values. Our results favor a Λnucleus interaction with an inner repulsive core. The non-mesonic weak decay widths of 4ΛH and 4ΛHe are reexamined on the basis of our measurements and updated knowledge of the mesonic decay processes. It is found that the non-mesonic decay of 4ΛHe predominantly takes place via the Λ + p → n + p process.
|Journal||Nuclear Physics A|
|Publication status||Published - 1998 Aug 24|