Consistency of spin-1 theories in external electromagnetic fields

Abstract

It is known that while spin-1 (Proca) theory with minimal electromagnetic interaction is marred by the Corben-Schwinger anomaly, the inclusion of specific types of 'anomalous' interactions lead to other difficulties such as non-causality of propagation, and the energy spectrum (in homogeneous magnetic fields of sufficient strength) becoming partially non-real. The authors investigate whether, by making the anomalous terms (introduced into the Duffin-Kemmer-Petiau equation) sufficiently general, it is possible to escape these inconsistencies. The answer, unfortunately, turns out to be in the negative. They comment briefly on other formulations for spin-1.