Precision measurement of the W boson decay branching fractions in proton-proton collisions at s=13 TeV

Abstract

The leptonic and inclusive hadronic decay branching fractions of the W boson are measured using proton-proton collision data collected at s=13 TeV by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb−1. Events characterized by the production of one or two W bosons are selected and categorized based on the multiplicity and flavor of reconstructed leptons, the number of jets, and the number of jets identified as originating from the hadronization of b quarks. A binned maximum likelihood estimate of the W boson branching fractions is performed simultaneously in each event category. The measured branching fractions of the W boson decaying into electron, muon, and tau lepton final states are (10.83±0.10)%, (10.94±0.08)%, and (10.77±0.21)%, respectively, consistent with lepton flavor universality for the weak interaction. The average leptonic and inclusive hadronic decay branching fractions are estimated to be (10.89±0.08)% and (67.32±0.23)%, respectively. Based on the hadronic branching fraction, three standard model quantities are subsequently derived: the sum of squared elements in the first two rows of the Cabibbo–Kobayashi–Maskawa (CKM) matrix ∑ij|Vij|2=1.984±0.021, the CKM element |Vcs|=0.967±0.011, and the strong coupling constant at the W boson mass scale, αS(mW2)=0.095±0.033.2 MoreReceived 19 January 2022Accepted 28 February 2022DOI:https://doi.org/10.1103/PhysRevD.105.072008Published 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.© 2022 CERN, for the CMS CollaborationPhysics Subject Headings (PhySH)Physical SystemsW & Z bosonsTechniquesHadron collidersParticles & Fields