The Thomas-Bargmann-Michel-Telegdi equation and the Muon g-2 experiment

We present a theoretical analysis of the relativistic theory of spin and how it can be used to understand the principles behind the recent Muon g-2 (E989) experiment at Fermilab. First, we discuss a covariant generalization of spin and its equation of motion in the presence of electromagnetic fields, the Thomas-Bargmann-Michel-Telegdi equation. We then generalize this equation to account for an electric dipole moment and a general curved spacetime. Finally, after showing why the g-factor is predicted to be g = 2 by the Dirac equation, we focus on the E989 experiment at Fermilab and how the anomalous magnetic moment of the muon a = (g-2)/2 is actually measured.