Hrayr Matevosyan

Louisiana State University/JLab

Quark-Gluon Vertex Dressing And Meson Masses Beyond Ladder-Rainbow Truncation.

We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. Within the current model, the more consistent dressed vertex limits the ladder-rainbow truncation error for vector mesons to be never more than 10% as the current quark mass is varied from the u/d region to the b region. We will also present our more recent results on fully dressing the quark-gluon vertex function with only two point gluon lines. Once again, we adopt the algebraic format afforded by the simple interaction kernel for solving the quark GAP equation. The resulting quark propagator functions exhibit large deviations from the corresponding Ladder-Rainbow solutions.

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