Perturbative determination of $\mathcal{O}(am)$ improvement on the QCD running coupling

Abstract

We present the perturbative results of the discretization errors proportional to the quark mass ($\mathcal{O}(a m)$) on the QCD running coupling within lattice perturbation theory. Our analysis involves calculating the 2-loop renormalization factor $Z_g$ using improved lattice actions for the $SU(N_c)$ gauge group and $N_f$ multiplets of fermions with a finite quark mass. We employ the background field method to compute $Z_g$, by calculating quantum corrections on both the background and quantum gluon propagator, respecting the $\mathcal{O}(a)$ improvement. This allows us to evaluate the perturbative $\mathcal{O}(a m)$ lattice errors which affect the determination of the running coupling. Eliminating these $\mathcal{O}(a m)$ effects is crucial for the nonperturbative studies of precision determinations of the strong coupling constant using lattice field theory.