QCD Coupling from a Nonperturbative Determination of the Three-Flavor Λ Parameter.

Mattia Bruno,Patrick Fritzsch,Stefan Schaefer,Rainer Sommer,Stefan Sint,Alberto Ramos,Hubert Simma,Mattia Dalla Brida,Tomasz Korzec

doi:10.1103/physrevlett.119.102001

Abstract

We present a lattice determination of the Λ parameter in three-flavor QCD and the strong coupling at the Z pole mass. Computing the nonperturbative running of the coupling in the range from 0.2 to 70GeV, and using experimental input values for the masses and decay constants of the pion and the kaon, we obtain Λ_{MS[over ¯]}^{(3)}=341(12) MeV. The nonperturbative running up to very high energies guarantees that systematic effects associated with perturbation theory are well under control. Using the four-loop prediction for Λ_{MS[over ¯]}^{(5)}/Λ_{MS[over ¯]}^{(3)} yields α_{MS[over ¯]}^{(5)}(m_{Z})=0.11852(84).

Highlights

QCD Coupling from a Nonperturbative Determination of the Three-Flavor Λ Parameter
In this work we present a subpercent determination of the strong coupling at the Z
Note that μ⋆ref is defined at a point with unphysical quark masses, where finite-size effects are smaller and simulations are easier than close to the physical point

Summary

Introduction

QCD Coupling from a Nonperturbative Determination of the Three-Flavor Λ Parameter We present a lattice determination of the Λ parameter in three-flavor QCD and the strong coupling at the

Results

Conclusion