Quark-gluon vertex from Nf=2 lattice QCD

Abstract

We study the quark-gluon vertex in the limit of vanishing gluon momentum using lattice QCD with 2 flavors of O(a) improved Wilson fermions, for several lattice spacings and quark masses. We find that all three form factors in this kinematics have a significant infrared strength, and that both the leading form factor ${\lambda }_1$, multiplying the tree-level vertex structure, and the scalar, chiral symmetry breaking form factor ${\lambda }_3$ are significantly enhanced in the infrared compared to the quenched (Nf=0) case. These enhancements are orders of magnitude larger than predicted by one-loop perturbation theory. We find only a weak dependence on the lattice spacing and quark mass.

24 pages, many figures. Minor changes, matches version published in Phys.Rev.D

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• Bethe-Salpeter kernel and properties of strange-quark mesons
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• Two-loop three-gluon vertex from the Curci-Ferrari model and its leading infrared behavior to all loop orders
• The impact of transverse Slavnov-Taylor identities on dynamical chiral symmetry breaking
• Gauge dependence of the quark gap equation: an exploratory study
• Small parameters in infrared QCD: The pion decay constant
• Overlap quark propagator near the physical pion mass
• A comprehensive approach to the physics of mesons
• The quark propagator and quark-gluon vertex from lattice QCD at finite temperature
• Restoring rotational invariance for lattice QCD propagators
• A window on infrared QCD with small expansion parameters
• Spinning Pairs: Supporting ${}^3{P}_0$ Quark-Pair Creation from Landau Gauge Green's Functions
• Influence of light quark loops on the Wigner phase with Dyson-Schwinger equations approach
• Semileptonic transitions: $B_{(s)}\to \pi (K)$; $D_s\to K$; $D\to \pi ,K$; and $K\to \pi$