Theoretical developments in weak hypernuclear decay

We present a theoretical overview of the developments in hypernuclear weak decay occurred in the last ten years or so, with special emphasis on the one- and two-nucleon-induced non-mesonic modes. Recent progress is discussed which lead to the solution of long-standing puzzles on the Γn/Γp ratio and the asymmetry parameter for Λ-hypernuclei. The theory-experiment agreement reached for the two-nucleon-induced rates is also analyzed. The various theoretical approaches adopted in the literature are summarized, highlighting those key ingredients of the baryon-baryon weak interaction that turned out to be relevant for the explanation of data. Perspectives for future studies on the ΔI=1/2 isospin rule in non-mesonic weak decay and on rare non-mesonic weak decays allowed to strangeness −2 hypernuclei are also indicated.