Neutral bions in the CP^{N-1} model for resurgence

Understand

Classical configurations in the CP^{N-1} model on R^1 x S^1 is studied with twisted boundary conditions.

• Starting from fractional instantons with the Z_N twisted boundary conditions, we review briefly the relevance of our study to resurgence phenomenon in field theory.
• We consider primarily configurations composed of multiple fractional instantons, called "neutral bions", which are identified as "perturbative infrared renormalons".
• We construct an explicit ansatz corresponding to topologically trivial configurations containing one fractional instanton (nu=1/N) and one fractional anti-instanton (nu=-1/N), which is guaranteed to become a solution of field equations asymptotically for large separations.