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Extended iterative scheme for QCD: the four-gluon vertex

  • L. Driesen
  • M. Stingl
Hadron physics

Abstract:

We study the self-consistency problem of the generalized Feynman rule (nonperturbatively modified vertex of zeroth perturbative order) for the 4-gluon vertex function in the framework of an extended perturbation scheme accounting for non-analytic coupling dependence through the Λ scale. Tensorial structure is restricted to a minimal dynamically closed basis set. The self-consistency conditions are obtained at one loop, in Landau gauge, and at the lowest approximation level (r=1) of interest for QCD. At this level, they are found to be linear in the nonperturbative 4-gluon coefficients, but strongly overdetermined due to the lack of manifest Bose symmetry in the relevant Dyson-Schwinger equation. The observed near decoupling from the 2-and-3-point conditions permits least-squares quasisolutions for given 2-and-3-point input within an effective one-parameter freedom. We present such solutions for NF=2 massless quarks and for the pure gluon theory, adapted to the 2-and-3-point coefficients determined previously.

Keywords

Feynman Rule Vertex Function Landau Gauge Perturbation Scheme Massless Quark 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • L. Driesen
    • 1
  • M. Stingl
    • 1
  1. 1.Institute for Theoretical Physics I, University of Münster, D-48149 Münster (Westf.), GermanyDE

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