Bootstrap dynamical symmetry breaking with strong Yukawa coupling

A bstract The newly discovered 126 GeV boson appears, by all counts, to be the Higgs boson of the Standard Model. Although this seems to exclude the existence of a heavy fourth generation quark doublet Q , for theoretical interest, we document a mechanism of dynamical mass generation via strong Yukawa coupling. The Goldstone boson G (the longitudinal component of the weak boson) couples to Q with Yukawa coupling λ Q . A “bootstrap” gap equation is constructed, where strong λ Q generates large quark mass m Q , thereby breaks electroweak symmetry breaking while self-consistently justifying G as a massless Goldstone particle in the loop. We solve the gap equation numerically and find m Q to be a couple of TeV. Putting in the light Higgs boson raises the strength of λ Q considerably, hence m Q as well, and does not look viable. But the equation allows for a dilaton of scale invariance violation, which has weaker coupling than the Higgs boson, except for gg and γγ modes. Whether a dilaton can be still compatible with current data is relegated to an appendix.