Speaker
Prof.
Stefan Sint
(Trinity College Dublin)
Description
A collaborative effort to determine the $\Lambda$-parameter in 3-flavour QCD by the ALPHA collaboration is currently being finalized. The strategy involves 2 finite volume schemes for the coupling, both defined with Schroedinger functional (SF) boundary conditions. I here discuss the scale evolution from an intermediate scale $1/L_0$ of about 4 GeV to scales of O(100) GeV using the traditional SF coupling and a 1-parameter family of close relatives. Our precise continuum extrapolated data allows for stringent tests of perturbation theory, which is then used to extract $L_0*\Lambda$ with an error below 3 per cent. To quote such a small error with confidence, non-perturbative data is required around alpha_s = 0.1. In particular, we have evidence that the apparent precision reached with data around alpha_s = 0.2 can be misleading.
(cf. related talks by A. Ramos and R. Sommer)
Primary authors
Dr
Alberto Ramos
(CERN)
Dr
Mattia Dalla Brida
(DESY - Zeuthen)
Dr
Patrick Fritzsch
(IFT, UAM/CSIC, Universidad Autonoma de Madrid)
Prof.
Rainer Sommer
(NIC @ DESY)
Prof.
Stefan Sint
(Trinity College Dublin)
Dr
Tomasz Korzec
(Bergische Universität Wuppertal)
