Angularities and other shapes

Abstract

I discuss soft-gluon resummation and power corrections for event shape distributions, mostly in e+ e- annihilation. I consider specifically the thrust, the C parameter, and the class of angularities, and show how factorization techniques and dressed gluon exponentiation lead to predictive models of power corrections that are firmly grounded in perturbative QCD. The scaling rule for the shape function for angularities is derived as an example. Finally, I make a few remarks on possible generalizations to hadron collisions, and on their relevance to LHC studies.

Comments: 10 pages, contribution to the FRIF workshop on first principles non-perturbative QCD of hadron jets, LPTHE, Paris, France, 12-14 Jan 2006