Speaker
Description
Precision measurements provide a powerful indirect probe of physics beyond the Standard Model, since new particles can modify electroweak and Higgs observables through quantum e>ects even when they are not directly observed. The evolving picture of the muon anomalous magnetic moment and the (W)-boson mass illustrates how the interpretation of precision tests changes as experimental and theoretical uncertainties are reduced. Equally important, increasing agreement with Standard Model predictions places stringent constraints on possible new physics. In this context, the rare loop-induced Higgs decays provide a sensitive test of additional charged particles and interactions. We explore an extended Higgs sector with an additional scalar doublet and a complex singlet, supplemented by a vector-like charged lepton and obtain constraints on model parameters. Subject to theoretical consistency and electroweak precision constraints, we examine possible modifications of (h\to Z\gamma) and (h\to \gamma\gamma) and related Higgs observables, illustrating the continuing potential of precision measurements to constrain new physics.