IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
The Non--Mesonic Weak Decay of Double--$\Lambda$ Hypernuclei: A Microscopic Approach
Autor/es:
BAUER, E; GARBARINO, G; RODRÍGUEZ PEÑA, C.A
Revista:
PHYS. REV. - C
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 2015 vol. 92 p. 14301 - 14310
ISSN:
0556-2813
Resumen:
The non--mesonic weak decay of double--$Lambda$ hypernuclei is studied within a microscopic diagrammatic approach. Besides the nucleon--induced mechanism, $Lambda No nN$ and $Lambda NNo nNN$, widely studied in single--$Lambda$ hypernuclei, additional hyperon--induced mechanisms, $Lambda Lambdao Lambda n$, $Lambda Lambdao Sigma^0 n$ and $Lambda Lambdao Sigma^-p$, are accessible in double--$Lambda$ hypernuclei and are investigated here. As in previous works on single--$Lambda$ 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 $^{10}_{LambdaLambda}$Be and $^{13}_{LambdaLambda}$B. Our predictions are compared with a few previous evaluations. The rate for the $Lambda Lambdao Lambda n$ decay is dominated by $K$--, $K^*$-- and $eta$--exchange and turns out to be about 2.5% of the free $Lambda$ decay rate, $Gamma_{Lambda}^{m free}$, while the total rate for the $Lambda Lambdao Sigma^0 n$ and $Lambda Lambdao Sigma^- p$ decays, dominated by $pi$--exchange, amounts to about 0.25% of $Gamma_{Lambda}^{m free}$. The experimental measurement of these decays would be essential for the beginning of a systematic study of the non--mesonic decay of strangeness $-2$ hypernuclei. This field of research could also shed light on the possible existence and nature of the $H$--dibaryon.