σ meson exchange effect on non-mesonic hypernuclear weak decay observables
We analyze the influence of σ meson exchange on the main non-mesonic hypernuclear weak decay observables: Total rate Γ<sub>NM</sub>, neutron-to-proton branching ratio Γ<sub>n/p</sub>, and proton asymmetry parameter a<sub>Λ</sub>. The σ meson exchange is added to t...
Guardado en:
| Autores principales: | , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2006
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/126519 |
| Aporte de: |
| Sumario: | We analyze the influence of σ meson exchange on the main non-mesonic hypernuclear weak decay observables: Total rate Γ<sub>NM</sub>, neutron-to-proton branching ratio Γ<sub>n/p</sub>, and proton asymmetry parameter a<sub>Λ</sub>. The σ meson exchange is added to the standard strangeness-changing weak ΛN → NN transition potential, which includes the exchange of the complete pseudoscalar and vector mesons octet (π, η, K, ρ, ω, K*). Using a shell model formalism, the σ meson weak coupling constants are adjusted to reproduce the recent Γ<sub>NM</sub> and Γ<sub>n/p</sub> experimental data for ⁵<sub>Λ</sub>He. Numerical results for the remaining observables of ⁵<sub>Λ</sub>He and all the observables of ¹²<sub>Λ</sub>C decays are presented. They clearly show that the addition of the σ meson improves the agreement with the data. However, its effect it is not enough to reproduce well the a<sub>Λ</sub> values, which means that other improvements of the model must be explored to explain the puzzle posed by the experiments. |
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