Bonn 2010 – scientific programme

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T: Fachverband Teilchenphysik

T 13: QCD (Theorie) IV / Quantenfeldtheorie II

T 13.5: Talk

Thursday, March 18, 2010, 17:55–18:10, HG XVI

Screened perturbation theory for 3d Yang-Mills theory and hot QCD — •Daniel Bieletzki — Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, D-48149 Münster

Perturbation theory for non-abelian gauge theories at finite temperature is plagued by infrared divergences which are caused by magnetic soft modes ∼ g²T, corresponding to gluon fields of a 3d Yang-Mills theory. While the divergences can be regulated by a dynamically generated magnetic mass on that scale, the gauge coupling drops out of the effective expansion parameter requiring summation of all loop orders for the calculation of observables. Some gauge invariant possibilities to implement such infrared-safe resummations are reviewed. We use a scheme based on the non-linear sigma model to estimate some of the contributions ∼ g⁶ of the soft magnetic modes to the QCD pressure through two loops.