Compatibility and combination of world W-boson mass measurements

TL;DR

This paper evaluates the consistency of W-boson mass measurements from different experiments using a unified framework, revealing tensions especially with the CDF result and highlighting the impact of PDF choices on combined measurements.

Contribution

It introduces a coherent method to assess compatibility of W-boson mass measurements across experiments considering theory uncertainties and PDF correlations.

Findings

The combined W-boson mass is 80394.6 ± 11.5 MeV with CT18 PDFs.

Removing the CDF measurement increases compatibility to 91%.

The combined value differs by 3.6 sigma from the CDF measurement.

Abstract

The compatibility of W-boson mass measurements performed by the ATLAS, LHCb, CDF, and D0 experiments is studied using a coherent framework with theory uncertainty correlations. The measurements are combined using a number of recent sets of parton distribution functions (PDF), and are further combined with the average value of measurements from the Large Electron-Positron collider. The considered PDF sets generally have a low compatibility with a suite of global rapidity-sensitive Drell-Yan measurements. The most compatible set is CT18 due to its larger uncertainties. A combination of all mW measurements yields a value of mW = 80394.6 +- 11.5 MeV with the CT18 set, but has a probability of compatibility of 0.5% and is therefore disfavoured. Combinations are performed removing each measurement individually, and a 91% probability of compatibility is obtained when the CDF measurement is removed. The corresponding value of the W boson mass is 80369.2 +- 13.3 MeV, which differs by 3.6 sigma from the CDF value determined using the same PDF set.