Axion cosmology with long-lived domain walls

By Takashi Hiramatsu, M. Kawasaki, K. Saikawa, Toyokazu Sekiguchi. 2012

192 citations recorded by the source corpus.

We investigate the cosmological constraints on axion models where the domain wall number is greater than one. In these models, multiple domain walls attached to strings are formed, and they survive for a long time. Their annihilation occurs due to the effects of explicit symmetry breaking term which might be raised by Planck-scale physics. We perform three-dimensional lattice simulations and compute the spectra of axions and gravitational waves produced by long-lived domain walls. Using the numerical results, we estimated relic density of axions and gravitational waves. We find that the existence of long-lived domain walls leads to the overproduction of cold dark matter axions, while the density of gravitational waves is too small to observe at the present time. Combining the results with other observational constraints, we find that the whole parameter region of models are excluded unless an unacceptable fine-tuning exists.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/0ecb211b32500dfbe6c31ea0d195dd0b432ac9a2

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Citations in the corpus

The dark-matter axion mass (2017, background): “But if Na 6= 1 then the model predicts stable domain walls which are a cosmological disaster [19, 20].”
Beyond the Standard Models with cosmic strings (2019, background): “However, there are mechanisms which can make the network decay, such as breaking into monopole (M) antimonopole (M) pairs [202–205], Hubble-induced mass of flat direction in supersymmetric theories [206, 207], symmetry restoration in runaway quintessential scenarios [125], or the formation of domain”
New experimental approaches in the search for axion-like particles (2018, background): “The annihilation of the DW network solves a cosmological disaster and provides another source of potential dark matter [209], dark radiation ALPs and gravitational waves [205,210,211].”
TASI Lectures on the Strong CP Problem and Axions (2018, background): “One can also make lower- fa dark matter axions using topological defects and fine tuning [95, 126, 127, 128].”
The landscape of QCD axion models (2020, background): “Although all numerical simulations [202–216] agree in confirming this qualitative result, no quantitative agreement has been reached yet regarding the efficiency of cold axion production from topological defects.”
Stellar recipes for axion hunters (2017, background): “The collapse of long-lived domain walls produces an additional number of axions, that contribute to and can be the dominant component of the dark matter density [77, 83].”
On the estimation of gravitational wave spectrum from cosmic domain walls (2013, methodology): “The magnitude of gravitational waves radiated from them can be estimated by using the quadrupole formula [40].”
A Review of Gravitational Waves from Cosmic Domain Walls (2017, background): “Furthermore, the results of numerical simulations of domain walls associated with ZN symmetric models imply that the shape of the spectrum slightly differs depending on the value of N [47].”