pi^- decay rates of p-shell hypernuclei revisited

Abstract

Explicit expressions for the parity-violating s-wave and the parity-conserving p-wave contributions to pi- weak-decay rates of Lambda hypernuclei in the 1p shell are given in the weak-coupling limit, to update previous shell-model calculations and to compare with recent pi- spectra and total decay rates measured by the FINUDA Collaboration. A useful sum rule for the summed strength of Lambda_{1s} --> pi- + proton_{1p} weak decays is derived. Fair agreement between experiment and calculations is reached, using the primary s-wave amplitude and Cohen-Kurath nuclear wavefunctions. The role of the p-wave amplitude is studied in detail for Lambda-15N and found to be secondary. Previous assignments of ground-state spin-parity values are confirmed and a new assignment is made, spin-parity 3/2+ for Lambda-15N, based on the substantial suppression calculated here for spin-parity 1/2+.

published version; new footnote 2 added in proof; related to recent FINUDA data, arXiv:0905.0623 [nucl-ex] submitted to Phys. Lett. B

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• New results on Mesonic Weak Decay of $p$-shell $\Lambda$-Hypernuclei
• Strangeness nuclear physics - 2010
• On the role of ground state correlations in hypernuclear non-mesonic weak decay
• First determination of the one-proton induced Non-Mesonic Weak Decay width of p-shell Λ-Hypernuclei
• Search for the neutron-rich hypernucleus 9ΛHe
• Structure of p-shell hypernuclei