2000/11/28 by C. Barbero, Barbero, C., D. Horvat +11
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th) #Nuclear physics research studies #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #nucl-th
paper · pdf · doi:10.48550/arxiv.nucl-th/0011092
44 pages, 2 eps figures, revtex, to appear in Phys. Rev. C
openalex publication_date 2000/11/28 · arxiv created 2002/09/20 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A general shell model formalism for the nonmesonic weak decay of the hypernuclei has been developed. It involves a partial wave expansion of the emitted nucleon waves, preserves naturally the antisymmetrization between the escaping particles and the residual core, and contains as a particular case the weak Λ-core coupling formalism. The Extreme Particle-Hole Model and the Quasiparticle Tamm-Dancoff Approximation are explicitly worked out. It is shown that the nuclear structure manifests itself basically through Pauli Principle, and a very simple expression is derived for the neutron and proton induced decays rates, Γn and Γp, which does not involve the spectroscopic factors. We use the standard strangeness-changing weak ΛN→ NN transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets (π,η,K,ρ,ω,K^*), taking into account some important parity violating transition operators that are systematically omitted in the literature. The interplay between different mesons in the decay of 12ΛC is carefully analyzed. With the commonly used parametrization in the One-Meson-Exchange Model (OMEM), the calculated rate ΓNM= Γn+Γp is of the order of the free Λ decay rate Γ0(ΓNM\rm th≅ Γ0) and is consistent with experiments. Yet, the measurements of Γn/p=Γn/Γp and of Γp are not well accounted for by the theory (Γn/p\rm th\lsim 0.42; Γp\rm th\gsim 0.60 Γ0). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified.