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 image 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 image isospin rule in non-mesonic weak decay and on rare non-mesonic weak decays allowed to strangeness −2 hypernuclei are also indicated.