Analysis of techni-dilaton as a dark matter candidate

Abstract

The almost conformal dynamics of walking technicolor (TC) implies the existence of the approximate scale invariance, which breaks down spontaneously by the condensation of anti-techni and techni-fermions. According to the Goldstone theorem, a spinless, parity-even particle, called techni-dilaton (TD), then emerges at low energy. If TC exhibits an extreme walking, TD mass is parametrically much smaller than that of techni-fermions (around 1 TeV), while its decay constant is comparable to the cutoff scale of walking TC. We analyze the light, decoupled TD as a dark matter candidate and study cosmological productions of TD, both thermal and non-thermal, in the early Universe. The thermal population is governed dominantly by single TD production processes involving vertices breaking the scale symmetry, while the non-thermal population is by the vacuum misalignment and is accumulated via harmonic and coherent oscillations of misaligned classical TD fields. The non-thermal population turns out to be dominant and large enough to explain the abundance of presently observed dark matter, while the thermal population is highly suppressed due to the large TD decay constant. Several cosmological and astrophysical limits on the light, decoupled TD are examined to find that the TD mass is constrained to be in a range between 0.01 eV and 500 eV. From the combined constraints on cosmological productions and astrophysical observations, we find that the light, decoupled TD can be a good dark matter candidate with the mass around a few hundreds of eV for typical models of (extreme) walking TC. We finally mention possible designated experiments to detect the TD dark matter.

26 pages. 16 figures; v2, expanded Section 2.4 on composite Higgs in light of newly discovered Higgs-like particle at LHC

References in corpus (15)

• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
• Dark Matter from new Technicolor Theories
• Holographic Estimate of Oblique Corrections for Technicolor
• Axino Cold Dark Matter Revisited
• X-ray photons from late-decaying majoron dark matter
• Conformal Window of Gauge Theories with Four-Fermion Interactions and Ideal Walking
• The S-parameter in Holographic Technicolor Models
• Conformal Dynamics for TeV Physics and Cosmology
• $S$ Parameter in the Holographic Walking/Conformal Technicolor
• Z Boson Propagator Correction in Technicolor Theories with ETC Effects Included
• Precision electro-weak parameters from AdS5, localized kinetic terms and anomalous dimensions
• Dilaton as a Dark Matter Candidate and its Detection
• Walking in the third millennium
• Conformal fixed point of SU(3) gauge theory with 12 fundamental fermions

Cited by in corpus (6)

• Dilatonic black holes in gravity's rainbow with a nonlinear source: the effects of thermal fluctuations
• Dilaton Interactions and the Anomalous Breaking of Scale Invariance of the Standard Model
• Holographic light dilaton at the conformal edge
• Very light dilaton and naturally light Higgs boson
• Composite (pseudo) scalar contributions to muon g-2
• Unitarity and Dilaton effective theory