New heavy-quark physics in the strongly Yukawa-coupled standard model.

Abstract

We show that for strong enough Yukawa coupling the electroweak standard-model quark finds it energetically advantageous to transform itself into a bound state in a Skyrme background. This picture implies a maximum mass for the quark and predicts the existence of an excited spin-(3/2 quark. Moreover, two-quark, color-antitriplet, and three-quark, color-singlet, bound states, which can be very deeply bound, are shown to occur. The spectrum is studied in the semiclassical approximation. On including the one-loop Casimir effect in the exponential background approximation one loses the present picture for the single-quark case. The leading decays of the excited states are estimated, which should provide clear experimental signatures of this scheme. For the quarkonium, surprisingly, the attractive potential is found to be dominated by QCD around the Bohr radius.