One-loop MSSM Contribution to the Weak Magnetic Dipole Moments of Heavy Fermions

Abstract

The MSSM predictions at the one-loop level for the weak-magnetic dipole moments of the $\tau$ lepton and the $b$ quark are analysed. The entire supersymmetric parameter space is scannedwith the usual GUT constraint and common squark and slepton mass parameters. The real part of $a_{\tau }^W$ is dominated by the chargino contribution, being the same order as the SM one or even larger in the high $\tan \beta$ region whereas the imaginary part, due to Higgs boson diagrams, is negligible comparedto the SM value. The real part of$a_b^W$ is controlled mainly by charginos andalso by gluinos, when the mixing in the bottom squark sector is large, to yield, for high $\tan \beta$, a contribution one order of magnitude largerthan the pure electroweak SM value but a factor five smaller than the standard QCD contribution. The imaginary part of $a_b^W$ is the same order as in the SM.

Comments: 14 pages, Latex, 4 eps and 1 ps figure, needs epsfig.sty. Minor changes, new references added. To be published in Phys. Lett. B