No abstract

We replace the standard model scalar doublet by a doublet of vector fields and generate masses by dynamical symmetry breaking. Oblique radiative corrections are small if the new vector bosons (B + , B 0 ) are heavy. In this note it is shown that the model has a low momentum scale and above Λ ≃ 2 TeV it does not respect the perturbative unitarity. From tree-graph unitarity the allowed region of B + (B 0 ) mass is estimated as m B + ≥ 369GeV (m B 0 ≥ 410 GeV) at Λ = 1 TeV.

We calculate the oblique electroweak corrections and confront them with the experiments in a composite Higgs version of the standard model. A vector-like weak doublet and a singlet fermion are added to the standard model without elementary Higgs. Due to quartic coupling, there is a mixing between the components of the new fields triggering electroweak symmetry breaking. The Peskin–Takeuchi S and T electroweak parameters are presented. The new sector of vector-like fermions is slightly constrained, T gives an upper bound on the mixing angle of the new fermions, which is already constrained by self-consistent gap-equations. S gives no constraints on the masses. This extension can give a positive contribution to T, allowing for a heavy Higgs boson in electroweak precision tests of the Standard Model.

Some ideas concerning the broken and approximate symmetries are discussed based on the simplest relativistic field theories satisfying the asymptotic condition.