Abstract
We calculate the bag parameters for neutral -meson mixing in and beyond the Standard Model, in full four-flavor lattice QCD for the first time. We work on gluon field configurations that include the effect of , , , and sea quarks with the highly improved staggered quark (HISQ) action at three values of the lattice spacing and with three quark masses going down to the physical value. The valence quarks use the improved nonrelativistic QCD action and the valence light quarks, the HISQ action. Our analysis was blinded. Our results for the bag parameters for all five operators are the most accurate to date. For the Standard Model operator between and mesons we find and . Combining our results with lattice QCD calculations of the decay constants using HISQ quarks from the Fermilab/MILC Collaboration and with experimental values for and oscillation frequencies allows determination of the Cabibbo-Kobayashi-Maskawa (CKM) elements and . We find , , and . Our results agree well (within ) with values determined from CKM unitarity constraints based on tree-level processes (only). Using a ratio to in which CKM elements cancel in the Standard Model, we determine the branching fractions and . We also give results for matrix elements of the operators , , and that contribute to neutral -meson width differences.
9 More- Received 5 July 2019
DOI:https://doi.org/10.1103/PhysRevD.100.094508
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