Phenomenology of the little Higgs model

Abstract

We study the low-energy phenomenology of the little Higgs model. We first discuss the linearized effective theory of the ''littlest Higgs model'' and study the low-energy constraints on the model parameters. We identify sources of the corrections to low-energy observables, discuss model-dependent arbitrariness, and outline some possible directions of extensions of the model in order to evade the precision electroweak constraints. We then explore the characteristic signatures to test the model in the current and future collider experiments. We find that the CERN LHC has great potential to discover the new SU(2) gauge bosons and the possible new U(1) gauge boson to the multi-TeV mass scale. Other states such as the colored vectorlike quark T and doubly charged Higgs boson ⌽ ϩϩ may also provide interesting signals. At a linear collider, precision measurements on the triple gauge boson couplings could be sensitive to the new physics scale of a few TeV. We provide a comprehensive list of the linearized interactions and vertices for the littlest Higgs model in the appendices.

Particle-antiparticle mixing,εK, ΔΓq, ASLq, ACP(Bd→ψKS), ACP(Bs→ψphi) and B→Xs,dγ in the Littlest Higgs model with T-parity

“…level, implying that the relevant scale of new physics, f , must be at least 2 − 3 TeV in order to be consistent with electroweak precision data [12]- [18]. As a consequence the contributions of the new particles to FCNC processes turn out to be at most 10 − 20% [19]- [22], which will not be easy to distinguish from the SM in view of experimental and theoretical uncertainties.…”

A vector-like heavy quark in the Littlest Higgs model

“…The smallness of the flavor-changing neutral currents(FCNC) transitons in the Standard Model is due to quantum loop effect and the GIM cancellation mechanism. In contrast, the FCNC in the LH model occurs at the tree level by the lagrangian [2] …”

“…The Standard Model quark doublets couple only to the gauge group SU (2) 1 . The charged currents in the LH model are given by [2] …”

Search for Heavy Resonances in the Dimuon Channel with the DØ Detector

“…The production cross-section through a Drell-Yan process is then proportional to the partial width Figure 2.5 shows the dependence of the branching ratios on the mixing angle [38]. For cot θ 0.5 the branching ratio to leptons is nearly independent of cot θ.…”