Nonmesonic weak decay of Λ hypernuclei: The three-nucleon induced mode

Abstract

The nonmesonic weak decay of Λ hypernuclei is studied within a microscopic diagrammatic approach which is extended to include the three-nucleon induced mechanism. We adopt a nuclear matter formalism which, through the local density approximation, allows us to model finite hypernuclei, a one-meson-exchange weak transition potential and a Bonn nucleon-nucleon strong potential. One-, two-and three-nucleon induced weak decay rates are predicted for 12 Λ C by including ground state correlations up to second order in the nucleon-nucleon potential and the recoil of the residual nucleus. Three-nucleon stimulated decays, ΛN N N → nN N N (N = n or p), are considered here for the first time. The obtained decay rates compare well with the latest KEK and FINUDA data. The three-nucleon induced rate turns out to be dominated by nnp-and npp-induced decays, it amounts to ∼ 7% of the total nonmesonic rate and it is ∼ 1/2 of the neutron-induced decay rate. The reduction effect of the nuclear recoil is particularly relevant for the three-nucleon induced rates (∼ 15%), less important for the two-nucleon induced rates (∼ 4%) and negligible for the one-nucleon induced rates. Given the non-negligible size of the three-nucleon induced contribution and consequently its importance in the precise determination of the complete set of decay rates, new measurements and/or experimental analysis are encouraged.

Bulk viscosity in neutron stars with hyperon cores

“…[15] (see Eqs. (37), (38), and Appen- Second, we calculated the r-mode instability windows following the approach of [16]. We show that the posi-tions of the critical frequency curve maxima are shifted to lower temperatures compared to previous calculations (cf.…”

“…[15] (see Eqs. (37), (38), and Appen- dices A, B). Expressions for ζ and λ's are derived within the non-superfluid hydrodynamics (Eqs.…”

“…(15) and the reaction rates from combining Eqs. (37), (41), and (42), into Eq. (13) for the bulk viscosity.…”

“…[24] for a review. In particular, the nucleon-induced Λ decay and formation, np ↔ Λp and nn ↔ Λn, is explored in hypernuclear physics [35][36][37] and in nucleonnucleon scatterings [38]. These processes are studied, e.g., within the one meson exchange (OME) approach, including the full pseudoscalar and vector meson octets [35], as well as with one-loop corrections [39] and account for decay of the virtual meson into a couple of others [36].…”

Effects of ΛΛ−ΞN mixing in the decay of S=−2 hypernuclei

“…The large amount of experimental and theoretical work in the strangeness −1 sector (see the reviews [6][7][8] ) has led to a consistent interpretation of the experimental data [9][10][11][12][13][14][15] , which includes not only lifetimes but also partial decay widths and asymmetries in the angular distribution of the emitted particles. Crucial elements for this success have been the inclusion of a scalar-isoscalar component [16][17][18][19] , in the weak decay mechanism, or the consideration of medium effects [20][21][22][23][24][25] in the decay observables through the incorporation of multiabsorption processes and final state interactions in the data analysis, among others. Little is known, comparatively, about the double strangeness systems, due to the small yields for binding two Λ particles after Ξ − capture and the ambiguities in interpreting events owing to the formation of particle-stable excited species.…”