Factorial growth at low orders in perturbative QCD: control over truncation uncertainties

Abstract

A method, known as “minimal renormalon subtraction” [Phys. Rev. D97 (2018) 034503, JHEP08 (2017) 62], relates the factorial growth of a perturbative series (in QCD) to the power p of a power correction Λp/Qp. (Λ is the QCD scale, Q some hard scale.) Here, the derivation is simplified and generalized to any p, more than one such correction, and cases with anomalous dimensions. Strikingly, the well-known factorial growth is seen to emerge already at low or medium orders, as a consequence of constraints on the Q dependence from the renormalization group. The effectiveness of the method is studied with the gluonic energy between a static quark and static antiquark (the “static energy”). Truncation uncertainties are found to be under control after next-to-leading order, despite the small exponent of the power correction (p = 1) and associated rapid growth seen in the first four coefficients of the perturbative series.