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 $m_A$ 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.

Comments: 11 pages revtex 6 figure files incoporated; slight modifications in discussion, with added brief comment on precision EW constraints; proof-read version to be published in PRD Rapid Communications (vol. 64)