Ghost-gluon coupling, power corrections and ${\Lambda }_{\overline{\mathrm{MS}}}$ from lattice QCD with a dynamical charm

Abstract

This paper is a first report on the determination of ${\Lambda }_{\text{msbar}}$ from lattice simulations with 2+1+1 twisted-mass dynamical flavours {\it 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 ${\mathrm{N}}_f$=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 ${\Lambda }_{\text{msbar}}$ 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 ${\alpha }_s(M_Z)$ much safer.

Comments: 11 pages, 3 figures, 3 tables (new version accepted to be published in Phys. Rev. D)