Quest for the Dynamical Origin of Mass

Abstract

Higgs boson ("sigma meson") as formulated in the Gell-Mann-Levy (GL) linear sigma model may be a composite object as it turned out in QCD. We shall discuss a composite Higgs boson in various models of dynamical symmetry breaking with large anomalous dimension at conformal fixed point: The techni-dilaton ("conformal Higgs") in the conformal/scale-invariant (walking) technicolor (TC) near the Caswell-Banks-Zaks conformal fixed point with γ_m&sime;1, the t^^-t composite ("top-Higgs") in the top-quark condensate model with γ_m&sime;2, and their variants in the models with 1<γ_m<2 (strong ETC TC, etc.). The conformal gauge dynamics is characterized by the essential singularity scaling, breakdown of the GL effective theory, and large anomalous dimension γ_m=1. In contrast to the folklore that TC is a "Higgsless theory", there exists a composite Higgs, techni-dilaton, in the conformal/scale-invariant TC as a composite pseudo Nambu-Goldstone boson which is a remnant of (approximate) conformal symmetry, with its mass mass arising from the (nonperturbative) scale anomaly. The techni-dilaton with the mass 500-600GeV, or other composite Higgs boson may be discovered at LHC.