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Abstract |
A model suited for calculating correlation functions in QCD from the ultraviolet to the infrared is
reviewed. The model consist in standard Faddeev-Popov Lagrangian for Landau gauge with an
extra mass term for gluons. It is shown that once this mass term is included, two and three
point correlation functions can be calculated with good precision at one-loop order even at
very low momenta in the quenched approximation. After that, the inclusion of quarks is
analyzed. It is shown that in that case, the perturbative calculation only gives the qualitative
behavior in some correlation functions. In particular, it is shown that the analysis of
spontaneous chiral symmetry breaking requires to go beyond perturbation theory. A non-
perturbative scheme but controlled by two small parameters is discussed and the
corresponding results are shown to agree with high precision to Monte Carlo numerical
simulations also in the quark sector. |
