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16th International Conference in Quantum ChromoDynamics (QCD12), Montpellier : France (2012)
Lattice measurement of \alpha_s with a realistic charm quark
B. Blossier1, Ph. Boucaud1, M. Brinet2, F. De Soto, X. Du2, V. Morenas3, O. Pene1, K. Petrov4, J. Rodriguez-Quintero

We report on an estimate of \alpha_s, renormalised in the MSbar scheme at the tau and Z^0 mass scales, by means of lattice QCD. Our major improvement compared to previous lattice calculations is that, for the first time, no perturbative treatment at the charm threshold has been required since we have used statistical samples of gluon fields built by incorporating the vacuum polarisation effects of u/d, s and c sea quarks. Extracting \alpha_s in the Taylor scheme from the lattice measurement of the ghost-ghost-gluon vertex, we obtain \alpha_s^{MSbar}(m^2_Z)=0.1200(14) and \alpha_s^{MSbar}(m^2_tau)=0.339(13).
1:  LPT - Laboratoire de Physique Théorique d'Orsay [Orsay]
2:  LPSC - Laboratoire de Physique Subatomique et de Cosmologie
3:  LPC - Laboratoire de Physique Corpusculaire [Clermont-Ferrand]
4:  LAL - Laboratoire de l'Accélérateur Linéaire
Physics/High Energy Physics - Lattice

Physics/High Energy Physics - Phenomenology
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