Cosmological aspects of the clockwork axion
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The clockwork axion refers to a family of aligned multi-axion models that lead to an exponential hierarchy between the scale of Peccei-Quinn symmetry breaking and the scale of the axion decay constant. The clockworking can bring the Peccei-Quinn-scale particles to within reach of collider experiments. In this work we are interested in whether cosmological observations impose any new constraints on the clockwork axion. If the universe reheats above the scale of Peccei-Quinn breaking, then the ensuing cosmological phase transition produces a network of topological defects, which have a qualitatively different behavior from the string-wall network in the usual axion models. We estimate the relic abundances of axion dark matter and dark radiation that arise from the emission of axions by the defect network, and we infer a constraint on the scale of Peccei-Quinn breaking and the mass spectrum. We find that the defect contribution to the axion dark matter relic abundance is generally negligible. However, the defect production of relativistic axion dark radiation becomes significant if the scale of Peccei-Quinn symmetry breaking is larger than 100 TeV, and measurements of ΔNeff provide a new probe of this class of models.
KeywordsCosmology of Theories beyond the SM Beyond Standard Model Topological Strings
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- M.A. Shifman, A.I. Vainshtein and V.I. Zakharov, Can Confinement Ensure Natural CP Invariance of Strong Interactions?, Nucl. Phys. B 166 (1980) 493 [INSPIRE].
- A.R. Zhitnitsky, On Possible Suppression of the Axion Hadron Interactions (in Russian), Sov. J. Nucl. Phys. 31 (1980) 260 [INSPIRE].
- M. Kuster, G. Raffelt and B. Beltran, Axions: theory, cosmology, and experimental searches. Proceedings, 1st Joint ILIAS-CERN-CAST axion training, Geneva, Switzerland, November 30 - December 2, 2005, Lect. Notes Phys. 741 (2008) 1.Google Scholar
- P. Di Vecchia and G. Veneziano, Chiral Dynamics in the Large N Limit, Nucl. Phys. B 171 (1980) 253 [INSPIRE].
- Vilenkin, Alex and Shellard, Cosmic Strings and Other Topological Defects, Cambridge University Press, Cambridge, U.K., (1994).Google Scholar
- T. Vachaspati, A.E. Everett and A. Vilenkin, Radiation From Vacuum Strings and Domain Walls, Phys. Rev. D 30 (1984) 2046 [INSPIRE].
- R.L. Davis, Cosmic Axions from Cosmic Strings, Phys. Lett. B 180 (1986) 225 [INSPIRE].
- A. Vilenkin and T. Vachaspati, Radiation of Goldstone Bosons From Cosmic Strings, Phys. Rev. D 35 (1987) 1138 [INSPIRE].
- D. Harari and P. Sikivie, On the Evolution of Global Strings in the Early Universe, Phys. Lett. B 195 (1987) 361 [INSPIRE].
- T.W.B. Kibble, Topology of Cosmic Domains and Strings, J. Phys. A 9 (1976) 1387 [INSPIRE].
- C. Hagmann and P. Sikivie, Computer simulations of the motion and decay of global strings, Nucl. Phys. B 363 (1991) 247 [INSPIRE].
- J. Preskill, M.B. Wise and F. Wilczek, Cosmology of the Invisible Axion, Phys. Lett. B 120 (1983) 127 [INSPIRE].
- L.F. Abbott and P. Sikivie, A Cosmological Bound on the Invisible Axion, Phys. Lett. B 120 (1983) 133 [INSPIRE].
- M. Dine and W. Fischler, The Not So Harmless Axion, Phys. Lett. B 120 (1983) 137 [INSPIRE].