Precision Electroweak Observables in the Minimal Moose Little Higgs Model

TL;DR

The paper assesses precision electroweak constraints on two Little Higgs constructions, showing the original Minimal Moose struggles with T parameter bounds. By adopting a Modified Minimal Moose with [SU(2) x U(1)]^2 gauge structure and equal light-fermion charges, the authors isolate a near oblique limit that suppresses large non-oblique corrections. Through detailed calculations of gauge, nonlinear sigma model, plaquette, fermion, and Higgs sector contributions to S and T, they identify viable parameter regions with f ≳ 2 TeV and demonstrate representative parameter sets achieving acceptable oblique corrections and manageable fine tuning. The findings suggest MMM is a viable TeV-scale extension with distinctive phenomenology testable at the LHC, while also highlighting the need for UV completion around 10 TeV.

Abstract

Little Higgs theories, in which the Higgs particle is realized as the pseudo-Goldstone boson of an approximate global chiral symmetry have generated much interest as possible alternatives to weak scale supersymmetry. In this paper we analyze precision electroweak observables in the Minimal Moose model and find that in order to be consistent with current experimental bounds, the gauge structure of this theory needs to be modified. We then look for viable regions of parameter space in the modified theory by calculating the various contributions to the S and T parameters.