Quark-gluon vertex from lattice QCD
Abstract
The quark-gluon vertex in Landau gauge is studied in the quenched approximation using the Sheikholeslami-Wohlert (SW) fermion action with mean-field improvement coefficients in the action and for the quark fields. We see that the form factor that includes the running coupling is substantially enhanced in the infrared, over and above the enhancement arising from the infrared suppression of the quark propagator alone. We define two different momentum subtraction renormalisation schemes — MOM-tilde (asymmetric) and MOM-bar (symmetric) — and determine the running coupling in both schemes. We find ΛMS-barNf = 0 = 300+150-180 +/- 55 +/- 30 MeV from the asymmetric scheme. This is somewhat higher than other determinations of this quantity, but the uncertainties — both statistical and systematic — are large. In the symmetric scheme, statistical noise prevents us from obtaining a meaningful estimate for ΛMS-bar
- Publication:
-
Journal of High Energy Physics
- Pub Date:
- September 2002
- DOI:
- 10.1088/1126-6708/2002/09/013
- arXiv:
- arXiv:hep-ph/0205318
- Bibcode:
- 2002JHEP...09..013S
- Keywords:
-
- High Energy Physics - Phenomenology;
- High Energy Physics - Lattice
- E-Print:
- 33 pages, 12 figures, JHEP3.cls Major restructuring, some discussion of infrared behaviour added, results unchanged. Published version