Nonmesonic Weak Decay Spectra of Light Hypernuclei

Abstract

The nonmesonic weak decay spectra of light hypernuclei have been evaluated in a systematic way. As theoretical framework we adopt the independent particle shell model with three different one-meson-exchange transition potentials. Good agreement with data is obtained for proton and neutron kinetic energy spectra of 4 Λ He, and 5 Λ He, when the recoil effect is considered. The coincidence spectra of proton-neutron pairs are also accounted for quite reasonably, but it was not possible to reproduce the data for the neutron-neutron pair spectra. It is suggested that the π + K meson-exchange model with soft monopole form factors could be a good starting point for describing the dynamics responsible for the decays of these two hypernuclei. The 4 Λ H spectra are also presented.

Nonmesonic weak decay dynamics from proton spectra of Λ-hypernuclei

“…are also shown. Since, according to (9), the value of Γ W is close to unity, the last result implies that the ratio R p is basically the proton decay rate. The theoretical analogs of (6) and (7) are, respectively…”

“…But this disagreement is not crucially important, since we are basically interested in disentangling the strangeness-flipping interaction among baryons. 9 Of course, both the 2N -NM decay and the FSIs, as well as the SRCs, are interesting physical phenomena in themselves, b Such a comparison is analogous to those done between the experimental data on electronnucleus and charged-current neutrino-nucleus scatterings that include the FSIs, with the planewave impulse approximation which doesn't include these processes. 39,40 Moreover, the results of our analysis are fully robust, in the sense that they will be valid even after the inclusion of the FSIs and the 2N -NM decay.…”

Nonmesonic weak decay of charmed hypernuclei

“…From previous works of Refs. [54,55,58,65,75,76], we know that to describe the NMWD in Λ hypernuclei with open-shell cores within the IPSM it is enough to make the replacementĴ 2 /ĵ 2 Λ → F j N J in the decay-rate expression with the DCSC, where F j N J is a spectroscopic factor. Making the same replacements here, i.e.Ĵ 2 /ĵ 2…”

“…[53]. Recently, it was suggested that the π + K meson-exchange model with soft monopole form factors could be a good starting point to describe this type of interaction in light and medium systems [54,55]. The lifetime of the free charmed baryon Λ + c is τ Λ + c = (2.00 ± 0.06) × 10 −13 s, which corresponds to the decay rate Γ(Λ + c → all) = (3.29 ± 0.10) × 10 −9 MeV.…”

Relativistic model for the nonmesonic weak decay of single-lambda hypernuclei

“…Using the expansion (25) and making the change of variablep 2 →p 12 as explained in Eq. (54), we are free to perform thep 1 integration according to Eq.…”