Weak Decay of Lambda Hypernuclei

Abstract

In this review we discuss the present status of strange nuclear physics, with special attention to the weak decay of Lambda hypernuclei. The models proposed for the evaluation of the Lambda decay widths are summarized and their results are compared with the data. Despite the recent intensive investigations, the main open problem remains a sound theoretical interpretation of the large experimental values of the ratio G_n/G_p. Although recent works offer a step forward in the solution of the puzzle, further efforts must be invested in order to understand the detailed dynamics of the non-mesonic decay. Even if, by means of single nucleon spectra measurements, the error bars on G_n/G_p have been considerably reduced very recently at KEK, a clean extraction of G_n/G_p is needed. What is missing at present, but planned for the next future, are measurements of 1) nucleon energy spectra in double coincidence and 2) nucleon angular correlations: such observations allow to disentangle the nucleons produced in one- and two-body induced decays and lead to a direct determination of G_n/G_p. For the asymmetric non-mesonic decay of polarized hypernuclei the situation is even more puzzling. Indeed, strong inconsistencies appear already among data. A recent experiment obtained a positive intrinsic Lambda asymmetry parameter, a_{Lambda}, for 5_{Lambda}He. This is in complete disagreement with a previous measurement, which obtained a large and negative a_{Lambda} for p-shell hypernuclei, and with theory, which predicts a negative value moderately dependent on nuclear structure effects. Also in this case, improved experiments establishing with certainty the sign and magnitude of a_{Lambda} for s- and p-shell hypernuclei will provide a guidance for a deeper understanding of hypernuclear dynamics and decay mechanisms.

129 pages, 21 figures, Submitted to Phys. Rept

References in corpus (3)

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• Final State Interactions in Hypernuclear Decay
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Cited by in corpus (54)

• Modern Theory of Nuclear Forces
• Strangeness in Nuclei and Neutron Stars
• Hypernuclear Physics for Neutron Stars
• Antinuclei in Heavy-Ion Collisions
• Exploring Hyperons and Hypernuclei with Lattice QCD
• Strangeness nuclear physics: a critical review on selected topics
• Bulk Viscosity in Neutron Stars from Hyperons
• Hyperons: the strange ingredients of the nuclear equation of state
• Formation of hypernuclei in high energy reactions within a covariant transport model
• Towards the solution of the Gn/Gp Puzzle in the Non-Mesonic Weak Decay of Lambda-Hypernuclei
• Neutron and proton energy spectra from the non-mesonic weak decays of 5_Lambda-He and 12_Lambda-C
• Coincidence Measurement of the Nonmesonic Weak Decay of ^{12}_{Lambda}C
• Exclusive Measurement of the Nonmesonic Weak Decay of ^{5}_ΛHe Hypernucleus
• Nucleon-Nucleon Coincidence Spectra in the Non-Mesonic Weak Decay of Lambda-Hypernuclei and the n/p Puzzle
• Proton spectra from Non-Mesonic Weak Decay of p-shell Lambda-Hypernuclei and evidence for the two-nucleon induced process
• Sigma Exchange in the Nonmesonic Decays of Light Hypernuclei and Violation of the Delta I=1/2 Rule
• Measurement of the proton spectra from Non-Mesonic Weak Decay of ${}_{\Lambda }^{5}He$, ${}_{\Lambda }^{7}Li$ and ${}_{\Lambda }^{12}C$
• $\Lambda N\to NN$ 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
• Model for hypernucleus production in heavy ion collisions
• pi^- decay rates of p-shell hypernuclei revisited
• Single and double coincidence nucleon spectra in the weak decay of Lambda hypernuclei
• Two-pion-exchange in the non-mesonic weak decay of $\Lambda$-hypernuclei
• Kinematical and nonlocality effects on the nonmesonic weak hypernuclear decay
• $\Lambda (1520)$ and $\Sigma (1385)$ in the nuclear medium
• Asymmetries in the Non-Mesonic Weak Decay of Polarized Lambda-Hypernuclei
• Asymmetry parameter for nonmesonic hypernuclear decay
• Antiproton physics
• Nonmesonic Weak Decay of $\Lambda$ Hypernuclei within a Nuclear Matter Formalism
• The Physics of DAFNE and KLOE
• First determination of the one-proton induced Non-Mesonic Weak Decay width of p-shell Λ-Hypernuclei
• Hadronic freeze-out in an effective relativistic mean field model
• Quantum interference terms in nonmesonic weak decay of $\Lambda$-hypernuclei within a RPA formalism
• Microscopic Approach to Nucleon Spectra in Hypernuclear Non-Mesonic Weak Decay
• $\sigma$ meson exchange effect on nonmesonic hypernuclear weak decay observables
• ${\Theta }^{+}$ Hypernuclei
• Nonmesonic weak decay of $\Lambda$ hypernuclei within a nuclear matter framework
• ${\Theta }^{+}$ hypernuclei in relativistic mean field model
• Ground state normalization in the nonmesonic weak decay of ${}_{\Lambda }^{12}C$ hypernucleus within a nuclear matter formalism
• Pionic decay of Lambda Hypernuclei in a Continuum Shell Model
• s-Wave Approximation for Asymmetry in Nonmesonic Decay of Finite Hypernuclei
• Microscopic approach to the proton asymmetry in the non-mesonic weak decay of Lambda-hypernuclei
• Relationships between nonmesonic-weak-decays in different hypernuclei
• Non-Mesonic Weak Decay of Lambda-hypernuclei: a new determination of the Gn/Gp ratio
• Nucleon-nucleon coincidence measurement in the non-mesonic weak decay of 5_Lambda-He and 12_Lambda-C hypernuclei
• 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
• Nonmesonic Weak Decay of $\Lambda$ Hypernuclei: The Three--Nucleon Induced Mode
• Next-to-leading order effective field theory $\Lambda N\to NN$ potential in coordinate space
• Effects of $\Lambda \Lambda -\Xi N$ mixing in the decay of $S=-2$ hypernuclei
• Spectator isobar production in the $A\left(\gamma ,\pi NN\right)B$ reaction
• 4-momentum conservation as the principal framework for mesonic decay: The case of helium-5-lambda
• A Cicerone for the physics of charm, Part I: production, spectroscopy, lifetimes