Ghost-gluon coupling, power corrections and $Λ_\bar MS$ from lattice QCD with a dynamical charm
This paper is a first report on the determination of $Λ_\msbar$ from lattice simulations with 2+1+1 twisted-mass dynamical flavours 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 $ N_f$=2 twisted-mass field configurations which prove the necessity to include non-perturbative power corrections in the description of the running. We provide with an estimate of $Λ_\msbar$ 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 $α_s(M_Z)$ much safer.