Improved description of dilepton production in τ − → ντP− decays Guevara, Adolfo López Castro, Gabriel Roig, P. We are indebted to Denis Epifanov and Yifan Jin for leading the Belle analysis of these decays, and measuring for the first time the τ→πe+e−ντ decays. We specially acknowledge Yifan Jin for sharing with us detailed information on their study and providing us with the simulated Monte Carlo generation. We also acknowledge Pablo Sánchez Puertas for useful comments on short distance constraints. A. G. was supported partly by the Spanish MINECO and European FEDER funds (Grant No. FIS2017-85053-C2-1-P) and Junta de Andalucía (Grant No. FQM-225) and partly by the Generalitat Valenciana (Grant No. Prometeo/2017/053). G. L. C. acknowledges funding from Ciencia de Frontera Conacyt Project No. 428218 and perfil Programa para el Desarrollo Profesional Docente (PRODEP) Idoneidad Docente—Profesorado de Tiempo Completo (IDPTC) 162336, and P. R. by the SEP-Cinvestav Fund (Project No. 142), Grant No. PID2020–114473 GB-I00 funded by MCIN/AEI/10.13039/501100011033 and by Cátedras Marcos Moshinsky (Fundación Marcos Moshinsky), that also supported A. G. P. R. also acknowledges ‘Paradigmas y Controversias de la Ciencia 2022’ Project No. 319395, Conacyt (Consejo Nacional de Ciencia y Tecnología). Recently, the Belle Collaboration reported the first measurements of the τ−→ντπ−e+e− branching fraction and the spectrum of the pion-dielectron system. In an analysis previous to Belle’s results, we evaluated this branching fraction which turned out to be compatible with that reported by Belle, although with a large uncertainty. This is the motivation to seek for improvement on our previous evaluation of τ−→ντπ−ℓ+ℓ− decays (ℓ=e, μ). In this paper we improve our calculation of the WP−γ∗ vertex by including flavor-symmetry breaking effects in the framework of the resonance chiral theory. We impose QCD short-distance behavior to constrain most parameters and data on the π−e+e− spectrum reported by the Belle Collaboration to fix the remaining free ones. As a result, improved predictions for the branching ratios and hadronic/leptonic spectra are reported, which are in good agreement with observations. Analogous calculations for the strangeness-changing τ−→ντK−ℓ+ℓ− transitions are reported for the first time. Albeit one expects the mπμ+μ− spectrum to be measured in Belle-II and the observables with ℓ=e can be improved, it is rather unlikely that the K channels can be measured due to the suppression factor |Vud/Vus|2=0.05. 2022-05-11T08:21:43Z 2022-05-11T08:21:43Z 2022-04-12 info:eu-repo/semantics/article Adolfo Guevara, Gabriel López Castro, and Pablo Roig. Improved description of dilepton production in τ − → ντP− decays. Phys. Rev. D 105, 076007 [DOI: 10.1103/PhysRevD.105.076007] http://hdl.handle.net/10481/74795 10.1103/PhysRevD.105.076007 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España American Physical Society