Abstract
We present lattice-QCD calculations of the hadronic form factors for the semileptonic decays , , and . Our calculation uses the highly improved staggered quark (HISQ) action for all valence and sea quarks and includes MILC ensembles with lattice spacings ranging from down to 0.042 fm. At most lattice spacings, an ensemble with physical-mass light quarks is included. The HISQ action allows all the quarks to be treated with the same relativistic light-quark action, allowing for nonperturbative renormalization using partial conservation of the vector current. We combine our results with experimental measurements of the differential decay rates to determine and . This result for is the most precise to date, with a lattice-QCD error that is, for the first time for the semileptonic extraction, at the same level as the experimental error. Using recent measurements from BES III, we also give the first-ever determination of from . Our results also furnish new Standard Model calculations of the lepton flavor universality ratios , , and , which are consistent within with experimental measurements. Our extractions of and , when combined with a value for , provide the most precise test of second-row Cabibbo-Kobayashi-Maskawa unitarity, finding agreement with unitarity at the level of one standard deviation.
43 More- Received 4 January 2023
- Accepted 11 May 2023
DOI:https://doi.org/10.1103/PhysRevD.107.094516
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