Weak decay of Λ hypernuclei

Oset, E.

doi:10.1016/s0146-6410(98)00057-x

Cited by 56 publications

(77 citation statements)

References 86 publications

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“…As this "non-mesonic" mode dominates, the decay of the lambda in the nuclear medium becomes sensitive to nuclear excitations. Finally, the decay is interesting because the empirical ∆I = 1/2 rule-nearly exact for the free decay-appears to be violated in the nuclear medium [4].…”

Section: Introductionmentioning

confidence: 99%

Relativistic treatment of hypernuclear decay

Zhou

Piekarewicz

1999

Phys. Rev. C

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We compute for the first time the decay width of Λ-hypernuclei in a relativistic mean-field approximation to the Walecka model. Due to the small mass difference between the Λ-hyperon and its decay products-a nucleon and a pion-the mesonic component of the decay is strongly Pauli blocked in the nuclear medium. Thus, the in-medium decay becomes dominated by the non-mesonic, or two-body, component of the decay. For this mode, the Λ-hyperon decays into a nucleon and a spacelike nuclear excitation. In this work we concentrate exclusively on the pion-like modes. By relying on the analytic structure of the nucleon and pion propagators, we express the nonmesonic component of the decay in terms of the spin-longitudinal response function. This response has been constrained from precise quasielastic ( p, n) measurements done at LAMPF. We compute the spin-longitudinal response in a relativistic random-phase-approximation model that reproduces accurately the quasielastic data. By doing so, we obtain hypernuclear decay widths that are considerably smaller-by factors of two or three-relative to existing nonrelativistic calculations.

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Section: Introductionmentioning

confidence: 99%

Relativistic treatment of hypernuclear decay

Zhou

Piekarewicz

1999

Phys. Rev. C

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“…pn͒ and neutron-stimulated ͑G n :Ln ! nn͒ processes [1]. Recently, the two-nucleon ͑2N ͒ process, LNN !…”

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confidence: 99%

Proton Energy Spectra in the Nonmesonic Weak Decay ofΛ12CandΛ28

et al. 2002

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Numbers of protons per Gamma hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of Gamma hypernuclei by the (pi+,K+) reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, Gamma((Lambda)n-->nn)/Gamma((Lambda)p-->np) ( = Gamma(n)/Gamma(p)) were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the Gamma(n)/Gamma(p) ratios are close to 1 both for 12LambdaC and 28LambdaSi in contradiction to theoretical expectations based on meson exchange models.

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“…Therefore, hypernuclei constitute not only a convenient framework to obtain information on the strong baryonbaryon interaction, but also, through their decay, and using the change of strangeness as signature, a suitable scenario to access both components of the four-fermion weak interaction, the parity-conserving (PC) and parityviolating (PV) amplitudes. The large amount of experimental and theoretical work in the strangeness −1 sector (see the reviews [6][7][8] ) has led to a consistent interpretation of the experimental data [9][10][11][12][13][14][15] , which includes not only lifetimes but also partial decay widths and asymmetries in the angular distribution of the emitted particles. Crucial elements for this success have been the inclusion of a scalar-isoscalar component [16][17][18][19] , in the weak decay mechanism, or the consideration of medium effects [20][21][22][23][24][25] in the decay observables through the incorporation of multiabsorption processes and final state interactions in the data analysis, among others.…”

Section: Introductionmentioning

confidence: 99%

“…Although the new hyperon-induced decay mechanisms provide novel information to constrain the theoretical models, only a limited number of theoretical groups have calculated decay rates for double-Λ hypernuclei [26][27][28] . With the present work we quantify, for the first time, the contribution to the decay of the 6 ΛΛ He hypernucleus of the new decay modes, which emerge when the strong interaction is carefully taken into account. Specifically, the weak decay process may occur from a ΛΛ, ΞN or ΣΣ state, which can be excited via the strong interaction from the initial ΛΛ pair.…”

Section: Introductionmentioning

confidence: 99%

Effects of ΛΛ−ΞN mixing in the decay of S=−2 hypernuclei

2018

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We study the non-mesonic weak decay of the doubly-strange hypernucleus 6 ΛΛ He within a model which considers the exchange of pseudoscalar and vector mesons. Special attention is paid into quantifying the strong interaction effects, focussing on the interaction among the two Λ hyperons which induces novel weak transitions, whereby ΛΛ, ΞN and ΣΣ states decay into a hyperon-nucleon pair. The initial strangeness −2 wave function is obtained from the solution of a G-matrix equation with the input of realistic strong baryon-baryon potentials, while the final hyperon-nucleon wave functions are derived analogously from a microscopic T-matrix calculation. The new ΛΛ → Y N decay rate studied in this work, ΓΛn + Γ Σ 0 n + Γ Σ − p , represents 3-4% of the total one-baryon induced non-mesonic decay and is remarkably affected by strong interaction effects. In particular, the relative importance of the partial decay rates, encoded in the ratio ΓΛn/(Γ Σ 0 n + Γ Σ − p ), gets inverted when the mixing to ΞN states is incorporated in the initial correlated ΛΛ wave function. This sensitivity can be used experimentally to learn about the strong interaction in the strangeness −2 sector.

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Weak decay of Λ hypernuclei

Cited by 56 publications

References 86 publications

Relativistic treatment of hypernuclear decay

Relativistic treatment of hypernuclear decay

Proton Energy Spectra in the Nonmesonic Weak Decay ofΛ12CandΛ28

Effects of ΛΛ−ΞN mixing in the decay of S=−2 hypernuclei

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