Hypernuclear weak decay puzzle

Autores
Barbero, César Alberto; Horvat, Dubravko; Krmpotić, Francisco; Kuo, T. T. S.; Narančić, Zoran; Tadić, Dubravko
Año de publicación
2002
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
A general shell model formalism for the nonmesonic weak decay of the hypernuclei has been developed. It involves a partial wave expansion of the emitted nucleon waves, preserves naturally the antisymmetrization between the escaping particles and the residual core, and contains as a particular case the weak Λ-core coupling formalism. The extreme particle-hole model and the quasiparticle Tamm-Dancoff approximation are explicitly worked out. It is shown that the nuclear structure manifests itself basically through the Pauli principle, and a very simple expression is derived for the neutron- and proton-induced decays rates Γn and Γp, which does not involve the spectroscopic factors. We use the standard strangeness-changing weak ΛN→NN transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets (π,η,K,ρ,ω,K*), taking into account some important parity-violating transition operators that are systematically omitted in the literature. The interplay between different mesons in the decay of ¹²ΛC is carefully analyzed. With the commonly used parametrization in the one-meson-exchange model (OMEM), the calculated rate ΓNM = Γn + Γp is of the order of the free Λ decay rate Γ⁰(ΓthNM ≅ Γ⁰) and is consistent with experiments. Yet the measurements of Γn/p = Γn / Γp and of Γp are not well accounted for by the theory (Γthn/p ≲ 0.42,Γthp ≳ 0.60Γ⁰). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified.
Facultad de Ciencias Exactas
Materia
Ciencias Exactas
Física
general shell model formalism
nonmesonic weak decay
hypernuclei
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-sa/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/125943

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repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Hypernuclear weak decay puzzleBarbero, César AlbertoHorvat, DubravkoKrmpotić, FranciscoKuo, T. T. S.Narančić, ZoranTadić, DubravkoCiencias ExactasFísicageneral shell model formalismnonmesonic weak decayhypernucleiA general shell model formalism for the nonmesonic weak decay of the hypernuclei has been developed. It involves a partial wave expansion of the emitted nucleon waves, preserves naturally the antisymmetrization between the escaping particles and the residual core, and contains as a particular case the weak Λ-core coupling formalism. The extreme particle-hole model and the quasiparticle Tamm-Dancoff approximation are explicitly worked out. It is shown that the nuclear structure manifests itself basically through the Pauli principle, and a very simple expression is derived for the neutron- and proton-induced decays rates Γ<sub>n</sub> and Γ<sub>p</sub>, which does not involve the spectroscopic factors. We use the standard strangeness-changing weak ΛN→NN transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets (π,η,K,ρ,ω,K*), taking into account some important parity-violating transition operators that are systematically omitted in the literature. The interplay between different mesons in the decay of ¹²<sub>Λ</sub>C is carefully analyzed. With the commonly used parametrization in the one-meson-exchange model (OMEM), the calculated rate Γ<sub>NM</sub> = Γ<sub>n</sub> + Γ<sub>p</sub> is of the order of the free Λ decay rate Γ⁰(Γ<sup>th</sup><sub>NM</sub> ≅ Γ⁰) and is consistent with experiments. Yet the measurements of Γ<sub>n/p</sub> = Γ<sub>n</sub> / Γ<sub>p</sub> and of Γ<sub>p</sub> are not well accounted for by the theory (Γ<sup>th</sup><sub>n/p</sub> ≲ 0.42,Γ<sup>th</sup><sub>p</sub> ≳ 0.60Γ⁰). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified.Facultad de Ciencias Exactas2002-11info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfhttp://sedici.unlp.edu.ar/handle/10915/125943enginfo:eu-repo/semantics/altIdentifier/issn/0556-2813info:eu-repo/semantics/altIdentifier/issn/1089-490Xinfo:eu-repo/semantics/altIdentifier/arxiv/nucl-th/0011092info:eu-repo/semantics/altIdentifier/doi/10.1103/physrevc.66.055209info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:30:18Zoai:sedici.unlp.edu.ar:10915/125943Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:30:18.369SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Hypernuclear weak decay puzzle
title Hypernuclear weak decay puzzle
spellingShingle Hypernuclear weak decay puzzle
Barbero, César Alberto
Ciencias Exactas
Física
general shell model formalism
nonmesonic weak decay
hypernuclei
title_short Hypernuclear weak decay puzzle
title_full Hypernuclear weak decay puzzle
title_fullStr Hypernuclear weak decay puzzle
title_full_unstemmed Hypernuclear weak decay puzzle
title_sort Hypernuclear weak decay puzzle
dc.creator.none.fl_str_mv Barbero, César Alberto
Horvat, Dubravko
Krmpotić, Francisco
Kuo, T. T. S.
Narančić, Zoran
Tadić, Dubravko
author Barbero, César Alberto
author_facet Barbero, César Alberto
Horvat, Dubravko
Krmpotić, Francisco
Kuo, T. T. S.
Narančić, Zoran
Tadić, Dubravko
author_role author
author2 Horvat, Dubravko
Krmpotić, Francisco
Kuo, T. T. S.
Narančić, Zoran
Tadić, Dubravko
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv Ciencias Exactas
Física
general shell model formalism
nonmesonic weak decay
hypernuclei
topic Ciencias Exactas
Física
general shell model formalism
nonmesonic weak decay
hypernuclei
dc.description.none.fl_txt_mv A general shell model formalism for the nonmesonic weak decay of the hypernuclei has been developed. It involves a partial wave expansion of the emitted nucleon waves, preserves naturally the antisymmetrization between the escaping particles and the residual core, and contains as a particular case the weak Λ-core coupling formalism. The extreme particle-hole model and the quasiparticle Tamm-Dancoff approximation are explicitly worked out. It is shown that the nuclear structure manifests itself basically through the Pauli principle, and a very simple expression is derived for the neutron- and proton-induced decays rates Γ<sub>n</sub> and Γ<sub>p</sub>, which does not involve the spectroscopic factors. We use the standard strangeness-changing weak ΛN→NN transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets (π,η,K,ρ,ω,K*), taking into account some important parity-violating transition operators that are systematically omitted in the literature. The interplay between different mesons in the decay of ¹²<sub>Λ</sub>C is carefully analyzed. With the commonly used parametrization in the one-meson-exchange model (OMEM), the calculated rate Γ<sub>NM</sub> = Γ<sub>n</sub> + Γ<sub>p</sub> is of the order of the free Λ decay rate Γ⁰(Γ<sup>th</sup><sub>NM</sub> ≅ Γ⁰) and is consistent with experiments. Yet the measurements of Γ<sub>n/p</sub> = Γ<sub>n</sub> / Γ<sub>p</sub> and of Γ<sub>p</sub> are not well accounted for by the theory (Γ<sup>th</sup><sub>n/p</sub> ≲ 0.42,Γ<sup>th</sup><sub>p</sub> ≳ 0.60Γ⁰). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified.
Facultad de Ciencias Exactas
description A general shell model formalism for the nonmesonic weak decay of the hypernuclei has been developed. It involves a partial wave expansion of the emitted nucleon waves, preserves naturally the antisymmetrization between the escaping particles and the residual core, and contains as a particular case the weak Λ-core coupling formalism. The extreme particle-hole model and the quasiparticle Tamm-Dancoff approximation are explicitly worked out. It is shown that the nuclear structure manifests itself basically through the Pauli principle, and a very simple expression is derived for the neutron- and proton-induced decays rates Γ<sub>n</sub> and Γ<sub>p</sub>, which does not involve the spectroscopic factors. We use the standard strangeness-changing weak ΛN→NN transition potential which comprises the exchange of the complete pseudoscalar and vector meson octets (π,η,K,ρ,ω,K*), taking into account some important parity-violating transition operators that are systematically omitted in the literature. The interplay between different mesons in the decay of ¹²<sub>Λ</sub>C is carefully analyzed. With the commonly used parametrization in the one-meson-exchange model (OMEM), the calculated rate Γ<sub>NM</sub> = Γ<sub>n</sub> + Γ<sub>p</sub> is of the order of the free Λ decay rate Γ⁰(Γ<sup>th</sup><sub>NM</sub> ≅ Γ⁰) and is consistent with experiments. Yet the measurements of Γ<sub>n/p</sub> = Γ<sub>n</sub> / Γ<sub>p</sub> and of Γ<sub>p</sub> are not well accounted for by the theory (Γ<sup>th</sup><sub>n/p</sub> ≲ 0.42,Γ<sup>th</sup><sub>p</sub> ≳ 0.60Γ⁰). It is suggested that, unless additional degrees of freedom are incorporated, the OMEM parameters should be radically modified.
publishDate 2002
dc.date.none.fl_str_mv 2002-11
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/125943
url http://sedici.unlp.edu.ar/handle/10915/125943
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/0556-2813
info:eu-repo/semantics/altIdentifier/issn/1089-490X
info:eu-repo/semantics/altIdentifier/arxiv/nucl-th/0011092
info:eu-repo/semantics/altIdentifier/doi/10.1103/physrevc.66.055209
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-sa/4.0/
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:SEDICI (UNLP)
instname:Universidad Nacional de La Plata
instacron:UNLP
reponame_str SEDICI (UNLP)
collection SEDICI (UNLP)
instname_str Universidad Nacional de La Plata
instacron_str UNLP
institution UNLP
repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
repository.mail.fl_str_mv alira@sedici.unlp.edu.ar
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