Classical anomalies for spinning particles Original Research Article

We discuss the phenomenon of classical anomaly. It is observed for 3D Berezin-Marinov (BM), Barducci-Casalbuoni-Lusanna (BCL) and Cortés-Plyushchay-Velázquez (CPV) pseudoclassical spin particle models. We show that quantum mechanically these different models correspond to the same P, T-invariant system of planar fermions, but the quantum system has global symmetries being not reproducible classically in full in any of the models. We demonstrate that the specific U(1) gauge symmetry characterized by the opposite coupling constants of spin s = +12 and s = −12 states has a natural classical analog in the CPV model but can be reproduced in the BM and BCL models in an obscure and rather artificial form. We also show that the BM and BCL models quantum mechanically are equivalent in any odd-dimensional space-time, but describe different quantum systems in even space-time dimensions.