Resolving the W-Boson Mass in the Lepton Specific Two Higgs Doublet Model

In 2022, the CDF Collaboration reported the W-boson mass, MW=80.4335±0.0094~GeV, which deviates from the Standard Model (SM) prediction, MWSM=80.357±0.006~GeV, by about 7σ. By contrast, the CMS Collaboration obtained MW=80.3602±0.0099~GeV, very close to the SM global electroweak fit value of ~80.357~GeV. Motivated by this situation, we reassess the W-boson mass within the Lepton-Specific Two Higgs Doublet Model (LS-2HDM). We perform random scans (generated with SARAH 4.13.0 and evaluated with SPheno 4.0.3) and confront the results with up-to-date theoretical and experimental constraints. The scan enforces vacuum stability, perturbative unitarity, and perturbativity; electroweak precision observables via the oblique parameters $(S,T,U)$; LEP bounds on H^±; rare B-meson decays; lepton flavor universality (LFU) in Z and τ decays; and LHC 13 TeV searches for additional Higgs bosons. Viable points are further tested with HiggsTools (HiggsSignals + HiggsBounds). In the LS-2HDM, if h₁ is the SM-like Higgs at mh₁125 GeV with |cos(β-α)|0.06, 17tanβ39, 144 mh₂414 GeV, and 435 m_A,H±685 GeV, the model reproduces the 2024 CMS W-boson mass within 3σ. Solutions near the 2022 CDF value, MW=80.4335±0.0094~GeV, survive; however, after applying all constraints, including HiggsTools, they approach it at best within 2σ. Our findings emphasize that the LS-2HDM favors the CMS results consistently with the current experimental results. On the other hand, while one can accommodate also the CDF results in this model theoretically, up-to-date electroweak precision bounds on the oblique parameters $(S,T,U)$ together with the SM-like Higgs and LFU constraints exclude these solutions and our results for $W-$boson mass can be only as close as about 2σ to the CDF results. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.