W-boson mass, electroweak precision tests, and SMEFT

Recently the CDF Collaboration at the Tevatron reported a significant discrepancy between the direct measurement of the W-boson mass and its Standard Model (SM) prediction based on electroweak precision tests (EWPTs). In this paper, we explore the potential origin of this discrepancy from physics beyond the SM. Explicitly, we work on a set of six-dimensional operators in the SM effective field theory (SMEFT) which are relevant to the EWPTs. By fitting to the data, we demonstrate that an upward shift in m(W) is driven by the operator O-T = 12(H+(D) over left right arrow H-mu)(2) with a coefficient c(T)(TeV/Lambda)(2) greater than or similar to 0.01. This suggests that the new physics scale favored by the CDF data should be multiple TeV for tree-level effects and sub-TeV for loop-level effects. One simple example is to introduce a hypercharge-free electroweak triplet scalar which can raise the c(T) value at tree level. We also study the potential to further test the relevant SMEFT by measuring Higgs-coupling, m(W), and other EWPTs at future circular e(-)e(+) colliders.

Automated summary

This paper investigates the discrepancy between the direct measurement and the Standard Model prediction of the W-boson mass reported by the CDF Collaboration at the Tevatron. The authors explore the potential origin of this discrepancy in physics beyond the Standard Model and demonstrate that it can be attributed to a specific operator in the Standard Model effective field theory. They suggest that the scale of new physics favored by the data should be multiple TeV for tree-level effects and sub-TeV for loop-level effects. The authors also propose a simple example to explain this phenomenon and discuss further testing of the relevant physics theory at future colliders.