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Induced Lorentz-Violating Chern-Simons Term in QED and Anomalous Contributions to Effective Action Expansions

Lai-Him Chan
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Abstract

I present a unified formulation of anomalous contributions in quantum field theories by calculating directly the effective action using the background field and covariant-derivative expansion technique. I use this method to determine uniquely the induced Chern-Simons term from the a Lorentz and CPT violating term in fermion QED Lagrangian. The outstanding ambiguity is resolved by properly taken into account the noncommutivity of $A$ and $\partial$. The resulting vacuum polarization tensor acquires a non-Feynman diagram anomalous contribution which accounts for the discrepancy between the present calculation and the other calculations.

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Lai-Him Chan. 2000-08-23. Induced Lorentz-Violating Chern-Simons Term in QED and Anomalous Contributions to Effective Action Expansions. https://arxiv.org/abs/hep-ph/9907349

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