Abstract
We use HPQCD’s recent lattice QCD determination of scalar, vector and tensor form factors to determine Standard Model differential branching fractions for , and . These form factors are calculated across the full range of the decay and have smaller uncertainties than previous work, particularly at low . For we find the Standard Model branching fraction in the region below the squared mass to exceed the LHCb results, with tensions as high as for . For the high region we see tensions. The tensions are much reduced by applying shifts to Wilson coefficients and in the effective weak Hamiltonian, moving them away from their Standard Model values consistent with those indicated by other phenomenology. We also update results for lepton-flavor ratios and and the “flat term,” in the differential branching fraction for . Our results for the form-factor dependent contributions needed for searches for lepton-flavor violating decays achieve uncertainties of 7%. We also compute the branching fraction with an uncertainty below 10%, for comparison with future experimental results.
31 More- Received 3 August 2022
- Accepted 6 December 2022
DOI:https://doi.org/10.1103/PhysRevD.107.014511
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