Vicent Mateu (Cambridge):
Eventshape distributions and αs determination
We use a factorization formula for thrust and
heavy jet mass distributions based on soft-collinear effective theory. The result is
applicable in the peak, tail, and far-tail regions. The formula includes three-loop
fixed-order QCD results, resummation of singular partonic terms with NNNLL accuracy
and hadronization effects from fitting a universal nonperturbative soft function defined
in field theory. We do not rely on Monte Carlo generators to determine nonperturbative
effects since they are not compatible with higher order perturbative analyses. We use
our theoretical expressions to fit for αs and the leading power correction in
thrust and heavy jet mass tail distributions, and also to moments of the thrust distribution.
Our determination is one of the world's most precise extractions of αs.
download document (pdf, 11,1 MB)