Semiperturbative construction for the quark-gluon vertex

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Fischer, CS
Alkofer, R
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Elsevier Science Bv
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We construct a model for the quark-gluon vertex of Landau gauge QCD. This is of twofold interest: on the one hand the quark-gluon interaction is at the heart of quark confinement, on the other hand it is a central element in hadron phenomenology based on QCD Greens functions. We employ the non-Abelian one-loop diagram in perturbation theory, which is of order N-c. As a novelty we replace the tree-level quark and gluon propagators in this diagram by their dressed counterparts solving the Dyson-Schwinger equations. The N.-suppressed Abelian diagram is an order of magnitude smaller in various kinematics. We also study the effect of ghost dressing factors on the vertex obtaining a construction in good agreement with recent low-momentum lattice calculations.
© 2005 Publish by Elsevier B.V. We thank M. Bhagwat, C. D. Roberts and P. Tandy for valuable discussions. The lattice data in figure 2 are a courtesy of the authors of [7]. F. L. E. thanks the hospitality of the Tiibingen Institute as well as a DAAD stipendium and Univ. Complutense travel grant. Partial support from grants FPA 2000-0956, BFM 2002-01003 (MCYT, Spain), Al 279/3-4, Fi 970/2-1, and GRK683 (DFG, Germany)
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