Infrared finite coupling in Sudakov resummation
Abstract
Description
New arguments are presented to emphasize the interest of the infrared finite coupling approach to power corrections in the context of Sudakov resummation. The more regular infrared behavior of some peculiar combinations of Sudakov anomalous dimensions, free of Landau singularities at large Nf, is pointed out. A general conflict between the infrared finite coupling and infrared renormalon approaches to power corrections is explained, and a possible resolution is proposed, which makes use of the arbitrariness of the choice of exponentiated constant terms. A simple ansatz for a 'universal' non-perturbative Sudakov effective coupling at large Nf follows naturally from these considerations. In this last version, a new result is presented: the striking emergence of an infrared finite perturbative effective coupling in the Drell-Yan process at large Nf (at odds with the infrared renormalon argument) within the framework of Sudakov resummation for eikonal cross sections of Laenen, Sterman and Vogelsang. Some suggestions for phenomenology at finite Nf, alternative to the shape function approach, are given.
Extended version of a talk given at the FRIF workshop on non-perturbative effects in jets (Paris, 12-14 January 2006). Version 3: additional material, comments and references. A new subsection introduced for the Drell-Yan process, showing that the Sudakov resummation for eikonal cross sections advocated by Laenen, Sterman and Vogelsang leads at large Nf to the emergence of a very simple infrared finite effective coupling in an entirely perturbative framework
Extended version of a talk given at the FRIF workshop on non-perturbative effects in jets (Paris, 12-14 January 2006). Version 3: additional material, comments and references. A new subsection introduced for the Drell-Yan process, showing that the Sudakov resummation for eikonal cross sections advocated by Laenen, Sterman and Vogelsang leads at large Nf to the emergence of a very simple infrared finite effective coupling in an entirely perturbative framework