Abstract :
Using an effective Lagrangian approach, we identify a class of models in which the loop-induced magnetic moment form-factors of muon are enhanced by possibly large factors (Λ2F/Λ2)(mτ/mμ)ln(mτ2/Λ2) or (Λ2F/Λ2)ln(mμ2/Λ2), where Λ is the scale of new physics and ΛF is the Fermi scale. These follow from left- and right-chirality mixing dimension-8 operators which for relatively small Λ, as required to explain the new (gμ−2) measurement, dominate over dimension-6 operators. Thus significant enhancement of new physics contributions to (gμ−2) and, in the presence of intergenerational couplings, also to the μ→eγ decay rate is possible. We discuss the compatibility of the (gμ−2) and μ→eγ experimental data in this case and comment on the enhancement of the electron anomalous magnetic moment. An explicit model is presented to illustrate the general results.
