In this paper we present a little Higgs model that has custodial $\mathrm{SU}\left(2\right)\mathrm{}$ as an approximate symmetry. This theory is a simple modification of the “minimal moose” model with $\mathrm{SO}\left(5\right)\mathrm{}$ global symmetries protecting the Higgs boson mass. This allows for a simple limit where TeV physics makes small contributions to precision electroweak observables. The spectrum of particles and their couplings to standard model fields are studied in detail. At low energies this model has two Higgs doublets and it favors a light Higgs boson from precision electroweak bounds, though for different reasons than in the standard model. The limit on the breaking scale, f, is roughly 700 GeV, with a top partner of 2 TeV, $W^{\prime }$ and $B^{\prime }$ of 2.5 TeV, and heavy Higgs partners of 2 TeV. These particles are easily accessible at hadron colliders.

• Received 30 July 2003

DOI:https://doi.org/10.1103/PhysRevD.69.035002