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SMEFT analysis of mW

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Emanuele Bagnaschi, John Ellis, Maeve Madigan, Ken Mimasu, Veronica Sanz, Tevong You

Original languageEnglish
Article number308
JournalJournal of High Energy Physics
Issue number8
PublishedAug 2022

Bibliographical note

Publisher Copyright: © 2022, The Author(s).

King's Authors


We use the Fitmaker tool to incorporate the recent CDF measurement of mW in a global fit to electroweak, Higgs, and diboson data in the Standard Model Effective Field Theory (SMEFT) including dimension-6 operators at linear order. We find that including any one of the SMEFT operators OHWB, OHD, Oℓℓ or OHℓ(3) with a non-zero coefficient could provide a better fit than the Standard Model, with the strongest pull for OHD and no tension with other electroweak precision data. We then analyse which tree-level single-field extensions of the Standard Model could generate such operator coefficients with the appropriate sign, and discuss the masses and couplings of these fields that best fit the CDF measurement and other data. In particular, the global fit favours either a singlet Z′ vector boson, a scalar electroweak triplet with zero hypercharge, or a vector electroweak triplet with unit hypercharge, followed by a singlet heavy neutral lepton, all with masses in the multi-TeV range for unit coupling.

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