Ghost-gluon coupling, power corrections and $\Lambda_{\bar{\rm MS}}$ from lattice QCD with a dynamical charm

TL;DR

This study determines the QCD scale parameter $\Lambda_{ar{ m MS}}$ using lattice QCD with dynamical charm, demonstrating the importance of non-perturbative corrections and achieving results consistent with experiments.

Contribution

First lattice QCD determination of $\Lambda_{ar{ m MS}}$ including dynamical charm quarks, with improved control over lattice artifacts and non-perturbative effects.

Findings

Good agreement of $\Lambda_{ar{ m MS}}$ with experimental values

Confirmation of the necessity of non-perturbative power corrections

First calculation with dynamical charm quark up to $\alpha_s(M_Z)$

Abstract

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.