Ghost-gluon coupling, power corrections and $\Lambda_{\bar{\rm MS}}$   from lattice QCD with a dynamical charm
  This paper is a first report on the determination of $\Lambda_{\msbar}$ 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 ${\rm N}_f$=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 $\Lambda_{\msbar}$ 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. 
B. Blossier, Ph. Boucaud, M. Brinet, F. De Soto, X. Du, M. Gravina, V.   Morenas, O. P\`ene, K. Petrov, J. Rodr\'iguez-Quintero
hep-lat