Muon anomalous magnetic moment: A harbinger for "new physics"

Standard model loop contributions to the muon anomalous magnetic moment, a(mu) = (g(mu)-2)/2, and their theoretical uncertainties are scrutinized. The status and implications of the recently reported 2.6 sigma experiment versus theory deviation a a(mu)(expt)-a(mu)(SM) = 426(165)x10(-11) are discussed. Possible explanations due to super-symmetric loop effects with m(SUSY)similar or equal to 55(-8)(+16) root tan beta GeV, radiative mass mechanisms at the 1-2 TeV scale and other "new physics" scenarios are examined.