One-loop MSSM contribution to the weak magnetic dipole moments of heavy fermions

The MSSM predictions at the one-loop level for the weak-magnetic dipole moments of the τ lepton and the b quark are analysed. The entire supersymmetric parameter space is scanned with the usual GUT constraint and common squark and slepton mass parameters. The real part of aWτ is dominated by the chargino contribution, being the same order as the SM one or even larger in the high tanβ region whereas the imaginary part, due to Higgs boson diagrams, is negligible compared to the SM value. The real part of aWb is controlled mainly by charginos and also by gluinos, when the mixing in the bottom squark sector is large, to yield, for high tanβ, a contribution one order of magnitude larger than the pure electroweak SM value but a factor five smaller than the standard QCD contribution. The imaginary part of aWb is the same order as in the SM.