Muon Anomalous Magnetic Moment, Two-Higgs-Doublet Model, and Supersymmetry
Abstract
The recent measurement on the muon anomalous magnetic moment a_\mu shows a 2.6\sigma deviation from the standard model value. We show that it puts strong constraints on the parameter space of the two-higgs doublet model (2HDM) II. The dominant contribution of the Higgses comes at the two-loop level, and in order to explain the data it favors a pseudoscalar A with a light mass range and a large \tan\beta. At 95% C.L., upper limit for m_{\scriptscriptstyle A} is 29 (55) (85) GeV for \tan\beta=30 (45) (60), and \tan \beta is bounded below at 17. This is in sharp contrast to the conclusion one draws from considering one-loop Higgs contributions alone. Finally, we also discuss the role of the Higgs contributions in the minimal supersymmetric standard model.