Decoupling heavy particles simultaneously
Abstract
The renormalization group is extended to cases where several heavy particles are decoupled at the same time. This involves large logarithms which are scale-invariant and so cannot be eliminated by a change of renormalization scheme. A set of scale-invariant running couplings, one for each heavy particle, is constructed without reference to intermediate thresholds. The entire heavy-quark correction to the axial charge of the weak neutral current is derived to next-to-leading order, and checked in leading order by evaluating diagrams explicitly. The mechanism for cancelling contributions from the top and bottom quarks in the equal-mass limit is surprisingly non-trivial.
Keywords
Cite
@article{arxiv.hep-ph/0601244,
title = {Decoupling heavy particles simultaneously},
author = {R. J. Crewther and S. D. Bass and F. M. Steffens and A. W. Thomas},
journal= {arXiv preprint arXiv:hep-ph/0601244},
year = {2010}
}
Comments
6 pages, 4 figures. Talk presented at the "QCD Down Under" Workshop, Barossa Valley and Adelaide, Australia, 10-19 March 2004, with ref 8 now linked to hep-ph/0507278