The Λ(1405)N → YN transition in the nuclear medium for non-mesonic absorption of a in nuclei

The non-mesonic transition Λ(1405)N→YN is investigated as one of the essential processes for the non-mesonic absorption of a in nuclei. Using a one-meson exchange model in the calculation of the transition, we find that the non-mesonic transition ratio ΓΛN/ΓΣN depends strongly on the ratio of the Λ(1405) (Λ*) couplings to and πΣ. Especially, a larger Λ*- coupling leads to enhancement of the transition to ΛN. Using the chiral unitary model for the description of the Λ*, we obtain ΓΛN/ΓΣ0N≈1.2 which is almost independent of the nucleon density, and find the total non-mesonic decay width of the Λ* in uniform nuclear matter to be 22MeV at the normal density.