Speculations on the W-mass measurement at CDF

he W mass determination at the Tevatron CDF experiment reported a deviation from the SM expecta-tion at the 7 sigma level. We discuss a few possible interpretations and their collider implications. We perform elec-troweak global fits under various frameworks and assumptions. We consider three types of electroweak global fits inthe effective-field-theory framework: the S-T, S-T-, and eight-parameter flavor-universal one. We discuss theamounts of tensions between different measurements reflected in these fits and the corresponding shifts in cent-ral values of these parameters. With these electroweak fit pictures in hand, we present a few different classes of mod-els and discuss their compatibility with these results. We find that while explaining the discrepancy, the singlegauge boson extensions face strong LHC direct search constraints unless the is fermiophobic (leptophobic),which can be realized if extra vector fermions (leptons) mix with the SM fermions (leptons). Vector-like top part-ners can partially generate the needed shift to the electroweak observables. The compatibility with the top squark isalso studied in detail. We find that the non-degenerate top squark soft masses enhance the needed operator coeffi-cients, enabling an allowed explanation compatible with current LHC measurements. Overall, more theoretical andexperimental developments are highly in demand to reveal the physics behind this discrepancy.

Automated summary

The W mass determination at the Tevatron CDF experiment shows a deviation from the SM expectation, and possible interpretations and collider implications are discussed in this paper. It is found that single gauge boson extensions face strong LHC direct search constraints, but the deviation can be explained by mixing extra vector fermions (leptons) with the SM fermions (leptons).