Infrared renormalon in $SU(N)$ QCD(adj.) on ${\mathbb{R}}^3\times S^1$

Abstract

We study the infrared renormalon in the gluon condensate in the $SU(N)$ gauge theory with $n_W$-flavor adjoint Weyl fermions (QCD(adj.)) on~${\mathbb{R}}^3\times S^1$ with the ${\mathbb{Z}}_N$ twisted boundary conditions. We rely on the so-called large-${\beta }_0$ approximation as a conventional tool to analyze the renormalon, in which only Feynman diagrams that dominate in the large-$n_W$ limit are considered while the coefficient of the vacuum polarization is set by hand to the one-loop beta function~${\beta }_0=11/3-2n_W/3$. In the large~$N$ limit within the large-${\beta }_0$ approximation, the W-boson, which acquires the twisted Kaluza--Klein momentum, produces the renormalon ambiguity corresponding to the Borel singularity at~$u=2$. This provides an example that the system in the compactified space~${\mathbb{R}}^3\times S^1$ possesses the renormalon ambiguity identical to that in the uncompactified space~${\mathbb{R}}^4$. We also discuss the subtle issue that the location of the Borel singularity can change depending on the order of two necessary operations.

Comments: 24 pages, 1 figure, the final version to appear in PTEP