Nucleon-Nucleon Coincidence Spectra in the Non-Mesonic Weak Decay of Lambda-Hypernuclei and the n/p Puzzle

Abstract

The main open problem in the physics of Lambda-hypernuclei is the lack of a sound theoretical interpretation of the large experimental values for the ratio G_n/G_p. To approach the problem, we have incorporated a Lambda N-> nN one-meson-exchange model in an intranuclear cascade code for a finite nucleus calculation of the nucleon-nucleon (angular and energy) coincidence distributions in the non-mesonic weak decay of 5_Lambda-He and 12_Lambda-C hypernuclei. The two-nucleon induced decay mechanism, Lambda np-> nnp, has been taken into account by means of the polarization propagator formalism in local density approximation. With respect to single nucleon spectra studies, the treatment of two-nucleon correlations allow a cleaner and more direct determination, from data, of G_n/G_p. Our results agree with the preliminary coincidence data of KEK-E462 for 5_Lambda-He. This allows us to conclude that G_n/G_p for 5_Lambda-He should be close to 0.46, the value predicted by our one-meson-exchange model for this hypernucleus. Unfortunately, to disentangle one- and two-body induced decay channels from experimental non-mesonic decay events, three-nucleon coincidences should be measured.

arXiv comment4 RevTeX pages, 5 figures; a small error in calculations has been corrected and Figs. 1, 2, 4 and Tab. II changed accordingly; minor rephrasing

References in corpus (14)

• Soft-core baryon-baryon potentials for the complete baryon octet
• The Weak Decay of Hypernuclei
• Weak Decay of Lambda Hypernuclei
• Theory of Weak Hypernuclear Decay
• Meson exchange in the weak decay of Lambda hypernuclei and the Gamma_n/Gamma_p ratio
• Final State Interactions in Hypernuclear Decay
• Neutron and proton spectra from the decay of $\Lambda$ hypernuclei
• Weak Decay of $\Lambda$ in Nuclei : Quarks vs Mesons
• Weak Decay of Lambda Hypernuclei
• Weak decays of medium and heavy Lambda-hypernuclei
• Nonmesonic weak decay of light hypernuclei with coherent $\Sigma$ mixing
• Erratum: Neutron and proton spectra from the decay of $\Lambda$ hypernuclei [Phys. Rev. C55, 735 (1997)]
• The Delta I=1/2 rule in non-mesonic weak decay of Lambda-hypernuclei
• Functional approach to the non-mesonic decay of Lambda-hypernuclei

Cited by in corpus (25)

• Strangeness nuclear physics: a critical review on selected topics
• Towards the solution of the Gn/Gp Puzzle in the Non-Mesonic Weak Decay of Lambda-Hypernuclei
• Exclusive Measurement of the Nonmesonic Weak Decay of ^{5}_ΛHe Hypernucleus
• Proton spectra from Non-Mesonic Weak Decay of p-shell Lambda-Hypernuclei and evidence for the two-nucleon induced process
• $\Lambda N\to NN$ weak interaction in effective field theory
• Exchange terms in the two--nucleon induced non--mesonic weak decay of $\Lambda$--hypernuclei
• On the role of ground state correlations in hypernuclear non-mesonic weak decay
• Two-pion-exchange in the non-mesonic weak decay of $\Lambda$-hypernuclei
• Single and double coincidence nucleon spectra in the weak decay of Lambda hypernuclei
• Asymmetries in the Non-Mesonic Weak Decay of Polarized Lambda-Hypernuclei
• Nonmesonic Weak Decay of $\Lambda$ Hypernuclei within a Nuclear Matter Formalism
• Proton emission off nuclei induced by kaons in flight
• Microscopic Approach to Nucleon Spectra in Hypernuclear Non-Mesonic Weak Decay
• Quantum interference terms in nonmesonic weak decay of $\Lambda$-hypernuclei within a RPA formalism
• Ground state normalization in the nonmesonic weak decay of ${}_{\Lambda }^{12}C$ hypernucleus within a nuclear matter formalism
• Nonmesonic weak decay of $\Lambda$ hypernuclei within a nuclear matter framework
• Kinetic energy sum spectra in nonmesonic weak decay of hypernuclei
• Current constraints on the EFT for the ΛN --> N N transition
• Relationships between nonmesonic-weak-decays in different hypernuclei
• Microscopic approach to the proton asymmetry in the non-mesonic weak decay of Lambda-hypernuclei
• Non-Mesonic Weak Decay of Lambda-hypernuclei: a new determination of the Gn/Gp ratio
• On the effect of the Delta(1232) in hypernuclear non-mesonic weak decay: a microscopic approach
• Nonmesonic Weak Decay Dynamics from proton spectra of $\Lambda$-Hypernuclei
• Relativistic model for the nonmesonic weak decay of single-lambda hypernuclei
• Effects of $\Lambda \Lambda -\Xi N$ mixing in the decay of $S=-2$ hypernuclei