What is the Magnetic Moment of the Electron?
  A direct definition of the intrinsic magnetic moment of the electron is given, which does not use infrared regularizations and interactions with external fields. The expression does not depend on the unavoidable ambiguities of the definition of a 1-electron state (exact form of its soft photon cloud). The method leads to the same analytic expression as the conventional approach, thus preserving the excellent agreement between theory and experiment. 
Othmar Steinmann (University of Bielefeld, Germany)