A Quick Look at Renormalons

TL;DR

Renormalons offer a systematic way to parametrize nonperturbative power corrections within a perturbative QCD framework, linking IR and UV contributions to observable 1/Q and 1/Q^2-type effects through the OPE and related constructs. The paper surveys renormalon basics, their phenomenological implications, and notable zeros in predictions (e.g., in heavy-quark decays) via KLN arguments and operator considerations, illustrating both cancellations and fixed matrix elements. It also discusses how renormalons underpin leading 1/Q corrections in event shapes like thrust, suggesting a possible universal link to hadronization models, while emphasizing model dependence and the limitations of extending these ideas beyond two-jet limits. Overall, the work highlights renormalons as a pragmatic, though incomplete, bridge between perturbative expansions and nonperturbative QCD, with potential impact on extracting $oldsymbol{ extalpha_s}$ and understanding power-suppressed corrections.

Abstract

We present a sketchy review of renormalon-based phenomenology. In particular, the leading, 1/Q corrections to various observables, KLN cancellations for power-suppressed corrections and the fixation of operator matrix elements are highlighted.