Séminaire de Physique ThéoriqueThe dynamics of massless spinning particles
Michael Stone (Université de l'Illinois)
Thursday 16 June 2016 14:00 - Tours - Salle 1180 (Bât E2)
I consider the relation between spin and the Berry-phase contribution to the anomalous velocity of massive and massless Dirac particles. After extending the Berry connection that depends only on the spatial components of the particle momentum to one that depends on the the space and time components in a covariant manner, I consider how the covariant connection enters the classical relativistic dynamics of spinning particles due to Mathisson, Papapetrou and Dixon. I’ll discuss the problems that arise with Lorentz covariance in the massless case, and trace them mathematically to a failure of the Wigner-translation part of the massless-particle little group to be an exact gauge symmetry in the presence of interactions, and physically to the fact that the measured position of a massless spinning particle is observer dependent.