The Non-Mesonic Weak Decay of Double- Hypernuclei: A Microscopic Approach

The non–mesonic weak decay of double–� hypernuclei is studied within a microscopic diagrammatic approach. Besides the nucleon–induced mechanism, �N → nN, widely studied in single–� hypernuclei, additional hyperon–induced mechanisms, �� → �n, �� → � 0 n and �� → � − p, are accessible in double–� hypernuclei and are investigated here. As in previous works on single–� hypernuclei, we adopt a nuclear matter formalism extended to finite nuclei via the local density approximation and a one–meson exchange weak transition potential (including the ground state pseudoscalar and vector octets mesons) supplemented by correlated and uncorrelated two–pion– exchange contributions. The weak decay rates are evaluated for hypernuclei in the region of the experimentally accessible light hypernuclei 10 Be and 13 B. Our predictions are compared with a few previous evaluations. The rate for the �� → �n decay is dominated by K–, K ∗ – and �– � � � � � � � � � � � − � � �   ,