Resummation of threshold corrections in QCD to power accuracy: the Drell-Yan cross section as a case study

Abstract

Resummation of large infrared logarithms in perturbation theory can, in certain circumstances, enhance the sensitivity to small gluon momenta and introduce spurious nonperturbative contributions. In particular, different procedures -- equivalent in perturbation theory -- to organize this resummation can differ by $1/Q$ power corrections. The question arises whether one can formulate resummation procedures that are explicitly consistent with the infrared behaviour of finite-order Feynman diagrams. We explain how this problem can be treated and resolved in Drell-Yan (lepton pair) production and briefly discuss more complicated cases, such as top quark production and event shape variables in the $e^+e^-$ annihilation.