{sigma} meson exchange effect on non-mesonic hypernuclear weak decay observables

Journal Article · Wed Feb 15 04:00:00 EST 2006 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.73.024309· OSTI ID:20771260

Barbero, C; Mariano, A ^[1]

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1. Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina)

We analyze the influence of {sigma} meson exchange on the main non-mesonic hypernuclear weak decay observables: Total rate {gamma}{sub NM}, neutron-to-proton branching ratio {gamma}{sub n/p}, and proton asymmetry parameter a{sub {lambda}}. The {sigma} meson exchange is added to the standard strangeness-changing weak {lambda}N{yields}NN transition potential, which includes the exchange of the complete pseudoscalar and vector mesons octet ({pi},{eta},K,{rho},{omega},K{sup *}). Using a shell model formalism, the {sigma} meson weak coupling constants are adjusted to reproduce the recent {gamma}{sub NM} and {gamma}{sub n/p} experimental data for {sub {lambda}}{sup 5}He. Numerical results for the remaining observables of {sub {lambda}}{sup 5}He and all the observables of {sub {lambda}}{sup 12}C decays are presented. They clearly show that the addition of the {sigma} meson improves the agreement with the data. However, its effect it is not enough to reproduce well the a{sub {lambda}} values, which means that other improvements of the model must be explored to explain the puzzle posed by the experiments.

• OSTI ID: 20771260
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 2 Vol. 73; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASYMMETRY
BOSON-EXCHANGE MODELS
BRANCHING RATIO
CARBON 12
COUPLING CONSTANTS
HELIUM 5
HYPERNUCLEI
LAMBDA BARYONS
NEUTRONS
NUCLEAR DECAY
NUCLEON-HYPERON INTERACTIONS
POTENTIALS
PROTONS
PSEUDOSCALAR MESONS
SHELL MODELS
STRANGENESS
VECTOR MESONS
WEAK INTERACTIONS