[sém. théorie] How nonperturbative is the infrared regime of QCD?

by Tissier Matthieu (Jussieu)

Friday 22 Mar 2019, 11:00 → 12:00 Europe/Paris

The short-distance physics of QCD can be treated within perturbation theory, thanks to asymptotic freedom. The long-distance regime, on the other hand, is often thought to be intrisically nonperturbative. In this seminar, I will question this common wisdom. This is an important issue since it may open the way to analytic determinations of some long-distance properties of QCD. In the first part of the talk, I will describe a simple phenomenological model which is equivalent to the standard QCD in the ultraviolet regime, which is well behaved in the infrared regime and which reproduces, within perturbation theory, several nontrivial properties of Yang-Mills theory. I will, more precisely, compare our predictions of the correlation functions of the gluons and ghosts with those obtained in lattice simulations. In the second part of the talk, I will discuss our attempts to justify this phenomenological model from first principles which may be related with the issue of the Gribov ambiguity.