Status and perspectives of experimental studies on hypernuclear weak decays

From the first beginning the weak decay of Λ-hypernuclei has been considered a very interesting physics case, since its study could shed light on several topics in nuclear and particle physics, among which the ΛN → N N four-baryon weak interaction not otherwise accessible. However, only in the last decade a substantial series of reliable experimental data samples has been produced thanks to the synergic effort of dedicated facilities at some laboratories in the world. The existing pattern of data on lifetimes, partial decay widths for mesonic and non-mesonic decay (both one- and two-nucleon induced) and energy spectra and correlations of the emitted particles is reviewed and compared with existing theoretical predictions. Updated tables and plots summarizing the existing experimental information are presented. For each item a brief account of possible new experimental efforts, approved, planned or futuristic is given. From these analyses the full pattern of partial decay widths for 4 He, 5 He, 11B and 12C is discussed. Rare decay channels and polarization studies ΛΛΛΛ are also briefly analyzed.