Simulating a CP-violating topological term in gauge theories

Abstract

We present recent results on the θ-dependence of four-dimensional SU(N) gauge theories, where θ is the coefficient of the CP-violating topological term in the Lagrangian. In particular, we study the scaling behavior of these theories, by Monte Carlo simulations at imaginary θ. The numerical results provide good evidence of scaling in the continuum limit. The imaginary θ dependence of the ground-state energy turns out to be well described by the first few terms of related expansions around θ 0, providing accurate estimates of the first few coefficients, up to O(θ 6). © 2012 IOP Publishing Ltd.