DESY Theory Seminar

ARES: resummation of event shapes

by Basem El-Menoufi (U Sussex)

Europe/Berlin
seminar room 2 (building 2A)

seminar room 2

building 2A

Description
Event shape observables (in e+e- to hadrons) played a major role in measuring the strong coupling, as they are very sensitive to QCD radiation. The omnipresent infrared singularities of QCD means that the perturbative expansion of the cross section suffers from potential large logarithms, which must then be resummed to obtain reliable predictions in regions when the event shape value is small. In this talk, I will discuss a resummation technique called 'ARES', Automated Resummation for Event Shapes, which in particular does not rely on any factorization property of the observable. I will present the general formalism and give closed formulae for the various ingredients up to next-to-next-to-leading-logarithmic (NNLL) accuracy. A wide class of event shapes obey an additivity property, which enables us to obtain fully analytic NNLL results. Finally, I will present analytic results for angularities and moment of energy-energy correlation.
Slides