269 research outputs found
On power corrections to the event shape distributions in QCD
We study power corrections to the differential thrust, heavy jet mass and
C-parameter distributions in the two-jet kinematical region in e^+e^-
annihilation. We argue that away from the end-point region, e>>
\Lambda_{QCD}/Q, the leading 1/Q-power corrections are parameterized by a
single nonperturbative scale while for e \Lambda_{QCD}/Q one encounters a novel
regime in which power corrections of the form 1/(Qe)^n have to be taken into
account for arbitrary n. These nonperturbative corrections can be resummed and
factor out into a universal nonperturbative distribution, the shape function,
and the differential event shape distributions are given by convolution of the
shape function with perturbative cross-sections. Choosing a simple ansatz for
the shape function we demonstrate a good agreement of the obtained QCD
predictions for the distributions and their lowest moments with the existing
data over a wide energy interval.Comment: 18 pages, LaTeX style, 4 figure
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