19110 2204.05260 10.1007/JHEP08(2022)308 308 308 SMEFT analysis of m W Regular Article - Theoretical Physics 1 22 2022 8 31 2022 5 10 2022 7 21 2022 8 1 2022 8 31 The Author(s) 2022 Open Access. This article is distributed under the terms of the Creative Commons Attribution License ( CC-BY 4.0 ), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited. 13130 2022 2022 8 8 Emanuele Bagnaschi emanuele.bagnaschi@cern.ch John Ellis john.ellis@cern.ch Maeve Madigan mum20@cam.ac.uk Ken Mimasu ken.mimasu@kcl.ac.uk Veronica Sanz veronica.sanz@uv.es Tevong You tevong.you@cern.ch grid.9132.9 0000 0001 2156 142X Theoretical Physics Department CERN CH-1211 Geneva 23 Switzerland grid.13097.3c 0000 0001 2322 6764 Theoretical Particle Physics and Cosmology Group, Department of Physics King’s College London London WC2R 2LS UK grid.177284.f 0000 0004 0410 6208 National Institute of Chemical Physics & Biophysics Rävala 10 10143 Tallinn Estonia grid.5335.0 0000000121885934 DAMTP University of Cambridge Wilberforce Road Cambridge CB3 0WA UK grid.470047.0 0000 0001 2178 9889 Instituto de Física Corpuscular (IFIC), Universidad de Valencia-CSIC E-46980 Valencia Spain grid.12082.39 0000 0004 1936 7590 Department of Physics and Astronomy University of Sussex Brighton BN1 9QH UK grid.5335.0 0000000121885934 Cavendish Laboratory University of Cambridge J.J. Thomson Avenue Cambridge CB3 0HE UK Abstract We use the Fitmaker tool to incorporate the recent CDF measurement of m W 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 O $$ \mathcal{O} $$ HWB , O $$ \mathcal{O} $$ HD , O $$ \mathcal{O} $$ ℓℓ or O H ℓ 3 $$ {\mathcal{O}}_{H\ell}^{(3)} $$ with a non-zero coefficient could provide a better fit than the Standard Model, with the strongest pull for O $$ \mathcal{O} $$ HD 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. Keywords Electroweak Precision Physics SMEFT ArXiv ePrint: 2204.05260