Combination of CDF and D0 Results on W Boson Mass and Width
V. M. Abazov
TL;DR
This paper presents a covariance-aware combination of Run 1 W boson mass and width measurements from CDF and DØ at the Fermilab Tevatron, including a novel two-parameter joint analysis of M_W and Γ_W. It reports Tevatron averages M_W = 80.456 ± 0.059 GeV and Γ_W = 2.115 ± 0.105 GeV, a joint M_W–Γ_W extraction, and a combined width incorporating indirect (R-based) information to yield Γ_W = 2.135 ± 0.050 GeV with a leptonic width of Γ(W→eν) = 224 ± 13 MeV. The indirect width from W/Z cross-section ratios is shown to be consistent with the direct width, providing a nontrivial SM test, and the work outlines methodological steps for robust cross-experiment combinations. The results are compatible with SM expectations and establish a framework for incorporating future, higher-precision Tevatron and (later) LHC data in joint electroweak fits.
Abstract
The results based on 1992-95 data (Run 1) from the CDF and DO experiments on the measurements of the W boson mass and width are presented, along with the combined results. We report a Tevatron collider average M_W = 80.456 +- 0.059 GeV. We also report the Tevatron collider average of the directly measured W boson width Gamma_W = 2.115 +- 0.105 GeV. We describe a new joint analysis of the direct W mass and width measurements. Assuming the validity of the standard model, we combine the directly measured W boson width with the width extracted from the ratio of W and Z boson leptonic partial cross sections. This combined result for the Tevatron is Gamma_W = 2.135 +- 0.050 GeV. Finally, we use the measurements of the direct total W width and the leptonic branching ratio to extract the leptonic partial width Gamma(W -> e nu) = 224 +- 13 MeV.