Abstract
The ratios (, ) provide sensitive tests of lepton universality and are a useful tool for new physics searches. The radiative corrections to are computed following a large- expansion to deal with hadronic effects: Chiral Perturbation Theory is enlarged by including the lightest multiplets of spin-one heavy states such that the relevant Green functions are well behaved at high energies. We find and , which imply and , compatible with and at of lepton universality, respectively. We test unitarity and bind nonstandard effective interactions with the decays.
- Received 20 July 2021
- Revised 1 October 2021
- Accepted 11 November 2021
DOI:https://doi.org/10.1103/PhysRevD.104.L091502
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society