Hypernuclear Weak Decay Puzzle

Details Hypernuclear Weak Decay Puzzle Hypernuclear Weak Decay Puzzle

2000-11-28

arxiv.org/abs/nucl-th/0011092v3

Physics

Nuclear Physics

Nuclear Theory

44 pages, 2 eps figures, revtex, to appear in Phys. Rev. C

Scientific paper

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 $\Lambda$-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, $\Gamma_n$ and $\Gamma_p$, which does not involve the spectroscopic factors. We use the standard strangeness-changing weak $\Lambda N\to NN$ transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets ($\pi,\eta,K,\rho,\omega,K^*$), 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 ${^{12}_\Lambda C}$ is carefully analyzed. With the commonly used parametrization in the One-Meson-Exchange Model (OMEM), the calculated rate $\Gamma_{NM}= \Gamma_n+\Gamma_p$ is of the order of the free $\Lambda$ decay rate $\Gamma^0(\Gamma_{NM}^{\rm th}\cong \Gamma^0)$ and is consistent with experiments. Yet, the measurements of $\Gamma_{n/p}=\Gamma_n/\Gamma_p$ and of $\Gamma_p$ are not well accounted for by the theory ($\Gamma_{n/p}^{\rm th}\lsim 0.42; \Gamma_p^{\rm th}\gsim 0.60 \Gamma^0$). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified.

Affiliated with

Also associated with

No associations

Rating

Hypernuclear Weak Decay Puzzle does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Hypernuclear Weak Decay Puzzle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hypernuclear Weak Decay Puzzle will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-398534