Decoupling heavy particles simultaneously

• Autor(a) principal: Crewther, R. J.
• Data de Publicação: 2005
• Outros Autores: Bass, S. D., Steffens, F. M., Thomas, A. W.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.nuclphysbps.2004.12.024; http://hdl.handle.net/11449/230967

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. © 2004 Elsevier B.V. All rights reserved.