Contribution of fermionic loops to the muon anomalous magnetic moment

The contribution of diagrams with fermion three vertex loops in lowest (fourth) order electroweak perturbation theory to the muon anomalous magnetic moment has been calculated. It reaches -(17.1/sin220W)x10-11 (without quarks in the fermion loop) and has to be taken into account for experiments with accuracy ∼10-10. One and two loop contributions of possible scalars and pseudoscalars to the magnetic moment are analyzed. Upper limits on their coupling constants are found for light and heavy particles. Their contribution to the reaction e+-→2γ is presented. 8 refs.; 2 figs.; 2 tabs