A new theoretical determination of Rτ /P (P = π, K)


  • Ignasi Rosell Universidad CEU Cardenal Herrera




Radiative decays, tau, pion, kaon, lepton universality, effective field theories, CKM unitarity, non-standard interactions


We have determined Rτ/P ≡ Γ(τ → P ντ [γ])/Γ(P → µνµ[γ]) (P = π, K). Whereas P decays are calculated by using Chiral Perturbation Theory (ChPT), τ decays have been studied with an effective approach where ChPT is enlarged by including the lightest resonances and following the high-energy behavior dictated by QCD. These ratios have allowed us to test the lepton universality and the CKM unitarity and also to search for bounds on non-standard interactions. Our results, δRτ/π = (0.18±0.57)% and δRτ/K = (0.97±0.58)%, are consistent with the previous theoretical determinations, but with much more robust assumptions, yielding a reliable uncertainty.


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How to Cite

Rosell I. A new theoretical determination of Rτ /P (P = π, K). Supl. Rev. Mex. Fis. [Internet]. 2022 May 18 [cited 2022 Dec. 7];3(3):0308047 1-5. Available from: https://rmf.smf.mx/ojs/index.php/rmf-s/article/view/6078