Nearly Conformal Composite Higgs Model.

We analyze a composite Higgs model based on the confining SU(3) gauge theory with N_{f}=8 Dirac fermions in the fundamental representation. This gauge theory has been studied on the lattice and shown to be well described by a dilaton effective field theory (EFT). Here we modify the EFT by assigning standard-model quantum numbers such that four of the composite pseudo-Nambu-Goldstone boson (pNGB) fields form the standard-model Higgs doublet, by coupling it to the top quark and by adding to the potential a term that triggers electroweak symmetry breaking.

Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents.

Two-color gauge theory with novel infrared behavior.

Using lattice simulations, we study the infrared behavior of a particularly interesting SU(2) gauge theory, with six massless Dirac fermions in the fundamental representation. We compute the running gauge coupling derived nonperturbatively from the Schrödinger functional of the theory, finding no evidence for an infrared fixed point up through gauge couplings g(2) of order 20. This implies that the theory either is governed in the infrared by a fixed point of considerable strength, unseen so far in nonsupersymmetric gauge theories, or breaks its global chiral symmetries producing a large number of composite Nambu-Goldstone bosons relative to the number of underlying degrees of freedom.

Parity doubling and the S parameter below the conformal window.

We describe a lattice simulation of the masses and decay constants of the lowest-lying vector and axial resonances, and the electroweak S parameter, in an SU(3) gauge theory with N(f)=2 and 6 fermions in the fundamental representation. The spectrum becomes more parity doubled and the S parameter per electroweak doublet decreases when N(f) is increased from 2 to 6, motivating study of these trends as N(f) is increased further, toward the critical value for transition from confinement to infrared conformality.

Toward TeV conformality.

We study the chiral properties of an SU(3) gauge theory with N{f} massless Dirac fermions in the fundamental representation when N{f} is increased from 2 to 6. For N{f}=2, our lattice simulations lead to a value of psi psi/F{3}, where F is the Nambu-Goldstone-boson decay constant and psi psi is the chiral condensate, which agrees with the measured QCD value. For N{f}=6, this ratio shows significant enhancement, presaging an even larger enhancement anticipated as N{f} increases further, toward the critical value for transition from confinement to infrared conformality.