Violation of custodial symmetry from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>W</mml:mi></mml:math>-boson mass measurements

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 nonzero 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 $4.5\ensuremath{\sigma}$ level. We contextualize the implications of our findings in light of other present anomalies in particle physics.

Topics & Concepts