Flavor physics and the triviality bound on the Higgs mass

The triviality of the scalar sector of the standard one-doublet Higgs model implies that this model is only an effective low-energy theory valid below some cut-off scale Λ. The underlying high-energy theory must include flavor dynamics at a scale of order Λ or greater in order to give rise to the different Yukawa couplings of the Higgs to ordinary fermions. This flavor dynamics will generically produce flavor-changing neutral currents and non-universal corrections to Z → bb. We show that the experimental constraints on the neutral D-meson mass difference imply that Λ must be greater than of order 21 TeV. We also discuss bounds on Λ from the constraints on extra contributions to the KL-KS mass difference and to the coupling of the Z boson to b-quarks. For theories defined about the infrared-stable Gaussian fixed-point, we estimate that this lower bound on Λ yields an upper bound of approximately 460 GeV on the Higgs bosonʹs mass, independent of the regulator chosen to define the theory.