Mario Gravina
(LPT - Universite Paris 11, Orsay (France))
15/06/2010, 16:40
Standard model parameters and renormalization
I present results concerning the non-perturbative evaluation of the ghost-gluon running QCD coupling constant from $N_f=2$ twisted-mass lattice calculations. Special attention is payed to the treatment of artifacts, in particular the quark mass, and to the different sources of systematical uncertainties. The value of $\Lambda_{\overline{MS}}$ is computed revealing the presence of a...
Rainer Sommer
(NIC, DESY)
15/06/2010, 17:00
Standard model parameters and renormalization
I discuss the status of different determinations of alpha_s,
motivating a precise and reliable computation from lattice
QCD. In order to suppress perturbative errors, the non-perturbative
computation has to reach high energy scales mu. Such results already
exist in the SF-scheme for Nf=0,2,3 . We now add the running with
four massless flavours in a range of alpha from about 0.07 to
0.3...
Paula Perez Rubio
(Universidad Autonoma de Madrid and Trinity College Dublin)
15/06/2010, 17:20
Standard model parameters and renormalization
Using the Schroedinger functional (SF) with a single staggered fermion
field we calculate the SF coupling in four-flavour QCD for a wide range
of energies and lattice sizes up to $L/a=16$. Preliminary results for the
continuum extrapolation of the step-scaling function are presented. To
reduce cutoff effects, one-loop ${\rm O}(a)$ improvement has been implemented.
Various cross checks...
