Scale-setting, flavour dependence and chiral symmetry restoration

Abstract

We determine the flavour dependence of the renormalisation-group-invariant running interaction through judicious use of both unquenched Dyson-Schwinger equation and lattice results for QCD's gauge-sector two-point functions. An important step is the introduction of a physical scale setting procedure that enables a realistic expression of the effect of different numbers of active quark flavours on the interaction. Using this running interaction in concert with a well constrained class of dressed--gluon-quark vertices, we estimate the critical number of active lighter-quarks above which dynamical chiral symmetry breaking becomes impossible: $n_f^{\mathrm{cr}}\approx 9$; and hence in whose neighbourhood QCD is plausibly a conformal theory.

8 pages, 4 figures, 2 tables

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• Empirical Consequences of Emergent Mass
• The strong running coupling from the gauge sector of Domain Wall lattice QCD with physical quark masses
• Discretization effects on renormalized gauge-field Green's functions, scale setting and gluon mass
• ${\gamma }^{\ast }\gamma \to \eta ,{\eta }^{\prime }$ transition form factors
• QCD Running Couplings and Effective Charges
• Mass-dependence of pseudoscalar meson elastic form factors
• Emergent Hadron Mass in Strong Dynamics
• Elastic electromagnetic form factors of vector mesons
• Reflections upon the Emergence of Hadronic Mass
• Vector-meson production and vector meson dominance
• Poincaré-covariant analysis of heavy-quark baryons
• Process-independent effective coupling. From QCD Green's functions to phenomenology
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• Contact interaction analysis of pion GTMDs
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• Proton tensor charges from a Poincaré-covariant Faddeev equation
• Pseudoscalar glueball mass: a window on three-gluon interactions
• Interplay of dynamical and explicit chiral symmetry breaking effects on a quark
• New Perspective on Hybrid Mesons
• Schwinger mechanism for gluons from lattice QCD
• N* Structure and Strong QCD
• Semileptonic $B_c\to {\eta }_c,J/\psi$ transitions
• Gluon mass scale through the Schwinger mechanism
• Color, Flavor, Temperature and Magnetic Field Dependence of QCD Phase Diagram: Magnetic Catalysis and its Inverse
• Emergent phenomena and partonic structure in hadrons
• A contact interaction model for the $\eta$ and ${\eta }^{\prime }$ mesons in a SDE-BSE approach to QCD: masses, decay widths and transition form factors
• Color-flavor dependence of the Nambu-Jona-Lasinio model and QCD phase diagram
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