Testing new physics with the electron g-2
Abstract
We argue that the anomalous magnetic moment of the electron (ae) can be used to probe new physics. We show that the present bound on new-physics contributions to ae is 8*10-13, but the sensitivity can be improved by about an order of magnitude with new measurements of ae and more refined determinations of alpha in atomic-physics experiments. Tests on new-physics effects in ae can play a crucial role in the interpretation of the observed discrepancy in the anomalous magnetic moment of the muon (amu). In a large class of models, new contributions to magnetic moments scale with the square of lepton masses and thus the anomaly in amu suggests a new-physics effect in ae of (0.7 +- 0.2)*10-13. We also present examples of new-physics theories in which this scaling is violated and larger effects in ae are expected. In such models the value of ae is correlated with specific predictions for processes with violation of lepton number or lepton universality, and with the electric dipole moment of the electron.