Mainz 2014 – scientific programme

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T: Fachverband Teilchenphysik

T 20: QCD (Theorie) 1

T 20.1: Talk

Monday, March 24, 2014, 11:00–11:15, P110

On color decomposition of QCD (one-loop) amplitudes and generalized shuffle relations. — •Christian Reuschle — KIT, Institute for Theoretical Physics, Karlsruhe, Germany

In recent years, the automated calculation of NLO processes has become more and more advanced, where NLO QCD processes with a multitude of partons in the final state have been of special interest. In order to handle the rather complex color structure of multi-parton QCD amplitudes one can thereby resort to color decomposition, where QCD amplitudes are decomposed into sums over simple color strings multiplied by kinematical factors, the so called partial amplitudes. In the simplest cases all the diagrams in a partial amplitude have the same cyclic ordering of the external legs. In more involved cases (tree-level QCD amplitudes with more than two quark-pairs and any one-loop QCD amplitude) this property is lost and partial amplitudes have to be further decomposed into primitive amplitudes. In the case of one-loop QCD amplitudes with more than one quark-pair the decomposition into primitive amplitudes is highly non-trivial and closed analytic expressions in the most general case of an arbitrary number of external quark-pairs and any number of gluons, so called all-n formulae, have in fact not been known until recently. In this talk I will report on a recent advancement in this direction and present the first all-n formulae for the color decomposition of QCD one-loop amplitudes with an arbitary number of external quark-pairs into primitive amplitudes, based on generalized shuffle relations.