Abstract

We examine the dark matter phenomenology of a composite electroweak singlet state. This singlet belongs to the Goldstone sector of a well-motivated extension of the Littlest Higgs with T-parity. A viable parameter space, consistent with the observed dark matter relic abundance as well as with the various collider, electroweak precision and dark matter direct detection experimental constraints is found for this scenario. T-parity implies a rich LHC phenomenology, which forms an interesting interplay between conventional natural SUSY type of signals involving third generation quarks and missing energy, from stop-like particle production and decay, and composite Higgs type of signals involving third generation quarks associated with Higgs and electroweak gauge boson, from vector-like top-partners production and decay. The composite features of the dark matter phenomenology allows the composite singlet to produce the correct relic abundance while interacting weakly with the Higgs via the usual Higgs portal coupling lambda _{text {DM}}sim O(1%), thus evading direct detection.

Highlights

  • One realization of the composite Higgs scenario is the Littlest Higgs [13,14,15,16,17,18,19]

  • The original model is strongly constrained by electroweak precision tests (EWPT) due to tree level contributions to electroweak observables [20,21,22,23,24,25,26,27]

  • T -Parity can be used as a stabilizing symmetry for a dark matter (DM) candidate, as the lightest T -odd particle is guaranteed to be stable

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Summary

Introduction

One realization of the composite Higgs scenario is the Littlest Higgs [13,14,15,16,17,18,19]. The new heavy states are odd under a discrete T -parity, contributions to electroweak observables are possible only at the 1-loop level This allows the symmetry breaking scale f to be O(1) TeV. The heavy gauge states contribute at tree level to the electroweak oblique parameters These contributions lead to stringent constraints from electroweak precision tests (EWPT), pushing the symmetry breaking scale of the original LH model f ∼ a few TeV Let us introduce a right-handed field ψc transforming as a doublet under the SM gauge group [SU (2)]1+2 This term respects the SM gauge group, each term by itself breaks SU (2)1 × SU (2) and cannot be generated by a reasonable UV theory which respects those gauge symmetries, unless they are spontaneously broken. Readers interested only in the details of the model used in this work, may skip directly to Sect. 2.1.3

Non-linear formulation of a massive odd doublet
Gauge sector
Goldstone sector
Matter sector
Scalar potential
Electroweak precision tests
Spectrum
Singlet-triplet mixing
Annihilation cross section
Higgs portal
Goldstone derivative interaction
Contact term
Relic abundance
Portal coupling dominance
Contact term dominance
Derivative interaction dominance
Direct detection
Conclusions
Full Text
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