Recent theoretical progress in hypernuclear decay

Some progress experienced recently in the field of hypernuclear weak decay is briefly summarized. Theoretical analyses of the double-coincidence nucleon spectra measured at KEK points towards a solution of the long-standing puzzle on the ratio Gamma(n)/Gamma(p) between the neutron(An Lambda n -> nn) and proton-induced (Lambda p -> np) decay. rates. Despite this improvement, the reaction mechanism for the hypernuclear non-mesonic weak decay seems to be not fully understood. Indeed, an intriguing problem, of more recent origin, is open: it concerns the asymmetry of the angular emission of non-mesonic weak decay protons from polarized hypernuclei. The important role played by final state interactions and two-nucleon induced decay channels, Lambda NN -> nNN, in the determination of Gamma(n)/Gamma(p) and the decay asymmetries is pointed out.