Violation of custodial symmetry from W-boson mass measurements

TL;DR

The paper investigates the discrepancy between the recent W-boson mass measurement and the Standard Model, finding evidence of custodial symmetry violation at 4.5 sigma, suggesting new physics beyond the Standard Model.

Contribution

It provides a detailed analysis of electroweak data and EFT deformations, revealing a non-zero T parameter indicating custodial symmetry violation.

Findings

Evidence for non-zero T parameter at 4.5σ

Indicates potential new physics beyond the Standard Model

Contextualizes findings with other particle physics anomalies

Abstract

The new measurement of the $W$-boson mass from the CDF collaboration shows a significant tension with the Standard Model prediction. We quantify this discrepancy within a state-of-the-art analysis of electroweak precision data and scrutinize the leading deformations of the Standard Model Effective Field Theory arising at dimension six. We find evidence for a non-zero value of the $T$ parameter, i.e. for a novel source of violation of custodial symmetry, pointing to physics beyond the Standard Model at the 4.5$\sigma$ level. We contextualize the implications of our findings in light of other present anomalies in Particle Physics.