Abstract
Abstract We consider cosmological consequences of the spontaneous breaking of a global symmetry that is anomalous under technicolor interactions, leading to the emergence of a light axion-like particle. Avoiding overclosure of the universe by such axions yields the upper bound f a ≲ 10 10 GeV on the symmetry breaking scale, corresponding to keV-scale axions. However, diffuse X-ray background data typically require larger values of f a . The overclosure and X-ray bounds can be reconciled if the axion initial amplitude of oscillations A i ∼ f a / 10 . In this case, a viable axionic dark matter candidate with a mass in the 50–100 eV range emerges. The detection of this type of dark matter may pose a challenge.
Highlights
We consider cosmological consequences of the spontaneous breaking of a global symmetry that is anomalous under technicolor interactions, leading to the emergence of a light axion-like particle
A main goal of future experiments at high energies is to uncover the mechanism for electroweak symmetry breaking (EWSB)
If a spontaneously broken global symmetry is anomalous under QCD, as in the PecceiQuinn (PQ) mechanism [2], the Goldstone boson, generally called an axion, associated with the broken symmetry [3] acquires a mass through confinement at ΛQCD
Summary
QCD dynamics generates a mass m ∼ Λ2QCD/f for the axion, where f is the scale of PQ symmetry breaking. In technicolor, there could be several sources of chiral symmetry breaking We will parameterize this effect by assuming a common techni-quark mass mQ. Even though this will not encode all aspects of chiral symmetry breaking in technicolor, our approach will capture the relevant physics and yield a good estimate for the size of the effects. In order to study the cosmological implications of the above setup, we will need to consider what happens to the axion when strong techni-dynamics sets in around the weak-scale in the early universe.
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