Towards the solution of the Gn/Gp Puzzle in the Non-Mesonic Weak Decay of Lambda-Hypernuclei

Abstract

One of the main open problems in the physics of Lambda-hypernuclei is the lack of a sound theoretical interpretation of the large experimental values for the ratio Gn/Gp=G(Lambda n -> nn)/G(Lambda p -> np). To approach the problem, we have incorporated a one-meson-exchange model for the Lambda N -> nN transition in finite nuclei in an intranuclear cascade code for the calculation of single and double-coincidence nucleon distributions corresponding to the non-mesonic weak decay of 5_Lambda-He and 12_Lambda-C. Due to the elimination of interferences, two-nucleon coincidences are expected to give a cleaner determination of Gn/Gp than single-nucleon observables. Single-nucleon distributions are found to be less sensitive to variations of Gn/Gp than double-coincidence spectra. The comparison of our results with preliminary KEK coincidence data allows us to extract a Gn/Gp ratio for 5_Lambda-He of 0.39+-0.11 when multinucleon induced channels are omitted.

arXiv comment12 RevTeX pages, 12 figures

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• Proton spectra from Non-Mesonic Weak Decay of p-shell Lambda-Hypernuclei and evidence for the two-nucleon induced process
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• Weak decays of 4He-Lambda
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• Relativistic model for the nonmesonic weak decay of single-lambda hypernuclei
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• Exchange Reactions with Dick Dalitz