Modified contour-improved perturbation theory

Gorazd Cvetič, Marcelo Loewe, Cristian Martinez, Cristián Valenzuela

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28 Scopus citations


The semihadronic tau decay width allows a clean extraction of the strong coupling constant at low energies. We present a modification of the standard "contour-improved" method based on a derivative expansion of the Adler function. The new approach has some advantages compared to contour-improved perturbation theory. The renormalization scale dependence is weaker by more than a factor of 2 and the last term of the expansion is reduced by about 10%, while the renormalization scheme dependence remains approximately equal. The extracted QCD coupling at the tau mass scale is by 2% lower than the contour-improved value. We find αs(MZ2)=0.1211±0.0010.

Original languageEnglish
Article number093007
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number9
StatePublished - 12 Nov 2010


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