The Littlest Higgs boson at a photon collider

Abstract

We calculate the corrections to the partial widths of the light Higgs boson in the Littlest Higgs model due to effects of the TeV-scale physics. We focus on the loop-induced Higgs coupling to photon pairs, which is especially sensitive to the effects of new particles running in the loop. This coupling can be probed with high precision at a photon collider in the process gamma gamma -> H -> b bbar for a light Higgs boson with mass 115 GeV <= MH <~ 140 GeV. Using future LHC measurements of the parameters of the Littlest Higgs model, one can calculate a prediction for this process, which will serve as a test of the model and as a probe for a strongly-coupled UV completion at the 10 TeV scale. We outline the prospects for measuring these parameters with sufficient precision to match the expected experimental uncertainty on gamma gamma -> H -> b bbar.

34 pages, 7 figures; v2: refs added, errors fixed in Eqs. 18, 20, A2-A4, A12, A15, numerics updated, Sec.VI added with expanded discussion of uncertainties, conclusions unchanged; v3: refs added, minor changes to text, version to appear in PRD