Nonmesonic Weak Decay of A-Hypernuclei within Independent-Particle Shell-Model

Journal Article · Fri May 21 04:00:00 EDT 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3448016· OSTI ID:21362087

Krmpotic, Franjo ^[1]; Galeao, Alfredo P ^[2]; Hussein, Mahir S ^[3]

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1. Instituto de Fisica La Plata, CONICET, Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, 1900 La Plata (Argentina)
2. Instituto de Fisica Teorica, UNESP-Univ. Estadual Paulista, Rua Dr. Bento Teobaldo Ferraz 271-Bl. II, 01140-070 Sao Paulo, SP (Brazil)
3. Departamento de Fisica Matematica, Instituto de Fisica da Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo, SP (Brazil)

After a short introduction to the nonmesonic weak decay (NMWD)LAMBDAN->nN of LAMBDA-hypernuclei we discuss the long-standing puzzle on the ratio GAMMA{sub n}/GAMMA{sub p}, and some recent experimental evidences that signalized towards its final solution. Two versions of the Independent-Particle-Shell-Model (IPSM) are employed to account for the nuclear structure of the final residual nuclei. They are: (a) IPSM-a, where no correlation, except for the Pauli principle, is taken into account, and (b) IPSM-b, where the highly excited hole states are considered to be quasi-stationary and are described by Breit-Wigner distributions, whose widths are estimated from the experimental data. We evaluate the coincidence spectra in {sub L}AMBDA{sup 4}He, {sub L}AMBDA{sup 5}He, {sub L}AMBDA{sup 12}C, {sub L}AMBDA{sup 16}O, and {sub L}AMBDA{sup 28}Si, as a function of the sum of kinetic energies E{sub nN} = E{sub n}+E{sub N} for N = n, p. The recent Brookhaven National Laboratory experiment E788 on {sub L}AMBDA{sup 4}He, is interpreted within the IPSM. We found that the shapes of all the spectra are basically tailored by the kinematics of the corresponding phase space, depending very weakly on the dynamics, which is gauged here by the one-meson-exchange-potential. In spite of the straightforwardness of the approach a good agreement with data is achieved. This might be an indication that the final-state-interactions and the two-nucleon induced processes are not very important in the decay of this hypernucleus. We have also found that the pi+K exchange potential with soft vertex-form-factor cutoffs (LAMBDA{sub p}iapprox =0.7 GeV, LAMBDA{sub K}approx =0.9 GeV), is able to account simultaneously for the available experimental data related to GAMMA{sub p} and GAMMA{sub n} for {sub L}AMBDA{sup 4}H, and {sub L}AMBDA{sup 5}He.

• OSTI ID: 21362087
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1245; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYONS
BOSON-EXCHANGE MODELS
BREIT-WIGNER FORMULA
COINCIDENCE METHODS
COINCIDENCE SPECTROMETRY
COUNTING TECHNIQUES
DECAY
DIMENSIONLESS NUMBERS
ELEMENTARY PARTICLES
ENERGY
ENERGY LEVELS
EXCITED STATES
FERMIONS
FINAL-STATE INTERACTIONS
FORM FACTORS
HADRONS
HYPERNUCLEI
INTERACTIONS
KINETIC ENERGY
MATHEMATICAL MODELS
MATHEMATICAL SOLUTIONS
MATHEMATICAL SPACE
NUCLEAR DECAY
NUCLEAR FRAGMENTS
NUCLEAR MODELS
NUCLEAR STRUCTURE
NUCLEI
NUCLEONS
PARTICLE MODELS
PARTICLE PROPERTIES
PAULI PRINCIPLE
PERIPHERAL MODELS
PHASE SPACE
SHELL MODELS
SPACE