Pi-Mesonic Weak Decay Rates of Light-to-Heavy Hypernuclei

Pionic decays of light-to-heavy Λ-hypernuclei are summarized including a review and the updated estimates which are based on the pion distorted waves generated by a sophisticated full-form optical potential. For heavy hypernuclei, the pion distortion effects yield a remarkable enhancement as large as two orders of magnitudes in comparison with the estimate without any distortion, where the Coulomb distortion is found to play an important role. The systematic calculations for all the sd-shell hypernuclei (including the updated p-shell results) predict that the totalπ0 and π− decay rates vary strikingly depending on the structures of individual hypernucleus and final nucleus. It is also shown by presenting the excitation functions that the partial pionic decay is selective enough to be utilized as a hypernuclear spectroscopic tool.