A ug 2 00 8 Ground state normalization in the nonmesonic weak decay of 12 Λ C hypernucleus

The nonmesonic weak decay width of 12 Λ C hypernucleus has been evaluated within a nuclear matter formalism, using the local density approximation. In addition to the one-body induced decay (ΛN → nN), it has been also considered the two-body induced decay (ΛNN → nNN). This second decay is originated from ground state correlations, where a renormalization procedure to ensure a ground state normalized to one has been implemented. Our results show that the plain addition of the twobody induced decay implies a lost in the ground state-norm, which adds ∼ 38% of spurious intensity to the nonmesonic weak decay width. By an adequate selection of the ΛN -transition potential, our result for the nonmesonic weak decay width of 12 Λ C is 0.956, in good agreement with the most recent data.