Electroweak precision fit and new physics in light of the W boson mass

Abstract

The $W$ boson mass is one of the most important electroweak precision observables for testing the Standard Model (SM) or its extensions. The very recent measured $W$ boson mass at the Collider Detector at Fermilab (CDF) shows about $7\ensuremath{\sigma}$ deviations from the SM prediction, which may challenge the internal consistency of the SM. By performing the global electroweak fit with the new $W$ boson, we present the new values of the oblique parameters: $S=0.06\ifmmode\pm\else\textpm\fi{}0.10$, $T=0.11\ifmmode\pm\else\textpm\fi{}0.12$, $U=0.13\ifmmode\pm\else\textpm\fi{}0.09$, or $S=0.14\ifmmode\pm\else\textpm\fi{}0.08$, $T=0.26\ifmmode\pm\else\textpm\fi{}0.06$ with $U=0$ and the corresponding correlation matrices, which strongly indicates the need for the nondegenerate multiplets beyond the SM. As a proof-of-concept, we show that the new results can be accommodated in the two-Higgs doublet model, where the charged Higgs boson has to be either heavier or lighter than both two heavy neutral Higgs bosons. The collider search for these non-SM Higgs bosons will provide a complementary way to test the new physics for $W$ boson mass anomaly.