Assessment of the a2(1320) tensor-meson contribution to η=η' → π0γγ decays
In light of the recent measurement of the η → πγγ decay by the KLOE-2 Collaboration, a previous analysis including vector- and scalar-meson exchange contributions using the vector meson dominance and linear sigma model frameworks, respectively, is extended in the present study to incorporate the eff...
| Autores: | , , |
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| Formato: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Recursos: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:dnet:uabarcelona_::8a1c999cc2a855527210202dc4bae394 |
| Acesso em linha: | https://ddd.uab.cat/record/327525 https://dx.doi.org/urn:doi:10.1103/y661-zt9k |
| Access Level: | acceso abierto |
| Resumo: | In light of the recent measurement of the η → πγγ decay by the KLOE-2 Collaboration, a previous analysis including vector- and scalar-meson exchange contributions using the vector meson dominance and linear sigma model frameworks, respectively, is extended in the present study to incorporate the effects of the a2(1320) tensor meson within a chiral context. Although the individual contribution of the a2 is negligible, its destructive interference with the vector-meson resonances is found to be significant, representing approximately 18% of the total signal and substantially affecting the diphoton invariant-mass distribution, especially at low mγγ values. The total decay rate is calculated to be Γ(η → πγγ) = 0.154(22) eV, which corresponds to a branching ratio of BR(η → πγγ) = 1.17(17) × 10. This result is approximately 5σ below the reported value of the particle data group, 2.55(22) × 10, while it is in very good agreement with the KLOE-2 measurement, 0.98 (11stat) (14syst) × 10. In contrast, the total contribution of the a2 is found to be negligible in η →■ πγγ, as this process is completely dominated by the exchange of an on-shell ω vector resonance. |
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