Ghost-gluon coupling, power corrections, and ^MS¯¯¯¯¯ from lattice QCD with a dynamical charm

Abstract

This paper is a first report on the determination of ^MS¯¯¯¯¯¯ from lattice simulations with 2+1+1 twisted-mass dynamical flavors via the computation of the ghost-gluon coupling renormalized in the MOM Taylor scheme. We show this approach allows a very good control of the lattice artefacts and confirm the picture from previous works with quenched and Nf=2 twisted-mass field configurations, which prove the necessity to include nonperturbative power corrections in the description of the running. We provide an estimate of ¿MS¯¯¯¯¯¯ in very good agreement with experimental results. To our knowledge, it is the first calculation with a dynamical charm quark which makes the running up to ¿s(MZ) much safer.