Speaker
Mattia Dalla Brida
(DESY - Zeuthen)
Description
In this talk we present the ALPHA-collaboration computation of the three-flavour QCD $\Lambda$-parameter. Starting from the value of $\Lambda$ in units of an intermediate energy scale $\mu=1/L_0 \sim 4\, {\rm GeV}$ (cf. talk by S. Sint), we first discuss the connection of this scale and a given hadronic scale, $1/L_{\rm had}$, of a few hundred MeV. The latter is obtained very precisely by determining the non-perturbative scale-evolution of the recently proposed gradient flow coupling between these scales. In a second step, $1/L_{\rm had}$ is expressed in terms of some measurable hadronic quantity using results from the CLS-collaboration effort. This allows the $\Lambda$-parameter to be determined in physical units.
Primary author
Mattia Dalla Brida
(DESY - Zeuthen)
Co-authors
Alberto Ramos Martinez
(CERN)
Hubert Simma
(DESY)
Mattia Bruno
(BNL)
Patrick Fritzsch
(H)
Rainer Paul Sommer
(DESY)
Stefan Schaefer
(Deutsches Elektronen-Synchrotron (DE))
Stefan Sint
(Trinity College Dublin (IE))
Tomasz Korzec
(University of Wuppertal)
