Possible Higgs Boson Effects on the Running of Third and Fourth Generation Quark Masses and Mixings.

The Schwinger-Dyson equation for the quark self-energy is solved for the case of the third and fourth quark generations. The exchanges of standard model gluons and Higgs bosons are taken into account. It is found that Higgs boson exchange dominates quark self-energy in the ultraviolet region for sufficiently large input quark masses, causing the running quark propagator mass to increase with energy-scale. No running of the quark mixing angles is found for input quark masses up to and including 500 GeV.