Matthias Jamin: A novel QCD coupling

Wednesday 23 Nov 2016, 13:00 → 14:00 Europe/Madrid

Seminar (IFAE)

Jelena Aleksic (IFAE), Joern Lange (IFAE Barcelona), John E Ward (IFAE)

The Quantum Chromodynamics (QCD) coupling, α_s, is not a physical observable of the theory since it depends on conventions related to the renormalization procedure. We introduce a definition of the QCD coupling, denoted by α^_s, whose running is explicitly renormalization scheme invariant. The scheme dependence of the new coupling α^_s is parameterized by a single parameter C, related to transformations of the QCD scale Λ. It is demonstrated that appropriate choices of C can lead to substantial improvements in the perturbative prediction of physical observables. As phenomenological applications, we study e+e− scattering and decays of the τ lepton into hadrons, both being governed by the QCD Adler function, as well as the scalar correlation function.