Direct search limits on the Littlest Higgs model

Abstract

Recent direct searches for new massive particles place constraints on the free parameters of the Littlest Higgs model. Depending on the choice of model free parameters, the direct search limit on the global symmetry breaking scale f can range from as low as a few hundred GeV to in excess of 4.5 TeV. The most stringent constraints are from exclusion of the A_H using high-mass dilepton resonance searches. The Z_H provides the best constraint in parameter regions where the A_H decouples from leptons. Current top pair resonance data approach but do not yet reach a useful limit in the anomaly-cancelling case, but do provide a constraint for a limited range of parameters in other cases. A neutral gauge boson is shown to be undetectable in dilepton resonances for a significant range of parameter space due to decoupling from Standard Model leptons, providing a counterexample to broad claims that a new neutral gauge boson (sometimes generically referred to as a Z') is ruled out to a high mass scale.

Conforms to published version. Minor clarifications and corrections, and additions to acknowledgments

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Cited by in corpus (4)

• Searching for t-bar t Resonances at the Large Hadron Collider
• Probing the Gauge Content of Heavy Resonances with Soft Radiation
• tbW vertex in the Littlest Higgs Model with T-parity
• Decays of the Littlest Higgs Z_H and the Onset of Strong Dynamics