paper

More on the infrared renormalon in QCD(adj.) on

arXiv:2005.07407 · doi:10.1093/ptep/ptaa096

Abstract

We present additional observations to previous studies on the infrared (IR) renormalon in QCD(adj.), the gauge theory with -flavor adjoint Weyl fermions on~ with the twisted boundary condition. First, we show that, for arbitrary finite~, a logarithmic factor in the vacuum polarization of the "photon" (the gauge boson associated with the Cartan generators of~) disappears under the ~compactification. Since the IR renormalon is attributed to the presence of this logarithmic factor, it is concluded that there is no IR renormalon in this system with finite~. This result generalizes the observation made by Anber and~Sulejmanpasic [J. High Energy Phys.\ \textbf{1501}, 139 (2015)] for and~ to arbitrary finite~. Next, we point out that, although renormalon ambiguities do not appear through the Borel procedure in this system, an ambiguity appears in an alternative resummation procedure in which a resummed quantity is given by a momentum integration where the inverse of the vacuum polarization is included as the integrand. Such an ambiguity is caused by a simple zero at non-zero momentum of the vacuum polarization. Under the decompactification~, where is the radius of the , this ambiguity in the momentum integration smoothly reduces to the IR renormalon ambiguity in~. We term this ambiguity in the momentum integration "renormalon precursor". The emergence of the IR renormalon ambiguity in~ under the decompactification can be naturally understood with this notion.

30 pages, 3 figures, the final version to appear in PTEP

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