$\theta$ Effects in Chern-Simons ${\rm QED}_{2+1}$ with a Four-Fermi Interaction

Abstract

We investigate the effects of the Chern-Simons coupling on the high energy behavior in the $(2+1)$-dimensional Chern-Simons QED with a four-Fermi interaction. Using the $1/N$ expansion we discuss the Chern-Simons effects on the critical four-Fermi coupling at $O(1/N)$ and the $\beta$ function around it. High-energy behavior of Green's functions is also discussed. By explicit calculation, we find that the radiative correction to the Chern-Simons coupling vanishes at $O(1/N)$ in the broken phase of the dynamical parity symmetry. We argue that no radiative corrections to the Chern-Simons term arise at higher orders in the $1/N$ expansion.