Fractionally charged Wilson loops as a probe of $\theta$-dependence in $C{P}^{N-1}$ sigma models: Instantons vs. large N

Patrick Keith-Hynes, H. B. Thacker

The behavior of Wilson loops with fractional charge is used to study the $\theta$-dependence of the free energy density $\epsilon (\theta )$ for the $C{P}^1$, $C{P}^5$, and $C{P}^9$ sigma models in two spa…