On Effective Charges, Event shapes and the size of Power Corrections

Abstract

We introduce and motivate the method of effective chsrges, and consider how to implement an all-orders resummation of large kinematical logarithms in this formalism. Fits for QCD Λand power corrections are performed for the e+e- event shape observables 1-thrust and heavy jet mass, and somewhat smaller power corrections are found than in the usual approach employing the ``physical scale'' choice.

8 pages, 7 figures. Talk given at the IPM-LPH06 School and Conference, Tehran, Iran, May 2006