Determination of Λ(MS)over-bar at five loops from holographic QCD

The recent determination of the beta-function of the quantum chromodynamics (QCD) running coupling alpha((MS) over bar)(Q(2)) to five-loops, provides a verification of the convergence of a novel method for determining the fundamental QCD parameter Lambda(s) based on the light-front holographic approach to nonperturbative QCD. The new five-loop analysis, together with improvements in determining the holographic QCD nonperturbative scale parameter k from hadronic spectroscopy, leads to an improved precision of the value of Lambda(s) in the (MS) over bar scheme close to a factor of two; we find Lambda((3))((MS) over bar) = 0.339 +/- 0.019 GeV for n(f) = 3, in excellent agreement with the world average, Lambda((3))((MS) over bar) = 0.332 +/- 0.017 GeV. We also discuss the constraints imposed on the scale dependence of the strong coupling in the nonperturbative domain by superconformal quantum mechanics and its holographic embedding in anti-de Sitter space.