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Title: Axion dark matter: strings and their cores

Abstract

Axions constitute a well-motivated dark matter candidate, and if PQ symmetry breaking occurred after inflation, it should be possible to make a clean prediction for the relation between the axion mass and the axion dark matter density. We show that axion (or other global) string networks in 3D have a network density that depends logarithmically on the string separation-to-core ratio. This logarithm would be about 10 times larger in axion cosmology than what we can achieve in numerical simulations. We simulate axion production in the early Universe, finding that, for the separation-to-core ratios we can achieve, the changing density of the network has little impact on the axion production efficiency.

Authors:
 [1];  [2]
  1. McGill University, Department of Physics,3600 rue University, Montréal QC H3A 2T8 (Canada)
  2. Institut für Kernphysik, Technische Universität Darmstadt,Schlossgartenstraße 2, D-64289 Darmstadt (Germany)
Publication Date:
Sponsoring Org.:
SCOAP3, CERN, Geneva (Switzerland)
OSTI Identifier:
22458446
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2016; Journal Issue: 01; Other Information: PUBLISHER-ID: JCAP01(2016)004; OAI: oai:repo.scoap3.org:13307; cc-by Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AXIONS; COMPUTERIZED SIMULATION; COSMOLOGICAL INFLATION; COSMOLOGY; DENSITY; NONLUMINOUS MATTER; SYMMETRY BREAKING; THREE-DIMENSIONAL CALCULATIONS; UNIVERSE

Citation Formats

Fleury, Leesa, and Moore, Guy D. Axion dark matter: strings and their cores. United States: N. p., 2016. Web. doi:10.1088/1475-7516/2016/01/004.
Fleury, Leesa, & Moore, Guy D. Axion dark matter: strings and their cores. United States. doi:10.1088/1475-7516/2016/01/004.
Fleury, Leesa, and Moore, Guy D. Mon . "Axion dark matter: strings and their cores". United States. doi:10.1088/1475-7516/2016/01/004.
@article{osti_22458446,
title = {Axion dark matter: strings and their cores},
author = {Fleury, Leesa and Moore, Guy D.},
abstractNote = {Axions constitute a well-motivated dark matter candidate, and if PQ symmetry breaking occurred after inflation, it should be possible to make a clean prediction for the relation between the axion mass and the axion dark matter density. We show that axion (or other global) string networks in 3D have a network density that depends logarithmically on the string separation-to-core ratio. This logarithm would be about 10 times larger in axion cosmology than what we can achieve in numerical simulations. We simulate axion production in the early Universe, finding that, for the separation-to-core ratios we can achieve, the changing density of the network has little impact on the axion production efficiency.},
doi = {10.1088/1475-7516/2016/01/004},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 01,
volume = 2016,
place = {United States},
year = {Mon Jan 04 00:00:00 EST 2016},
month = {Mon Jan 04 00:00:00 EST 2016}
}
  • Axions constitute a well-motivated dark matter candidate, and if PQ symmetry breaking occurred after inflation, it should be possible to make a clean prediction for the relation between the axion mass and the axion dark matter density. We show that axion (or other global) string networks in 3D have a network density that depends logarithmically on the string separation-to-core ratio. This logarithm would be about 10 times larger in axion cosmology than what we can achieve in numerical simulations. We simulate axion production in the early Universe, finding that, for the separation-to-core ratios we can achieve, the changing density ofmore » the network has little impact on the axion production efficiency.« less
  • This Letter reports the results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 μ eV . The search excludes the range of axion-photon couplings predicted by plausible models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume haloscope at subkelvin temperatures, thereby reducing thermal noise as well as the excess noise from the ultralow-noise superconducting quantum interference device amplifier used for the signal power readout. Finally, ongoing searches will provide nearly definitive tests of the invisible axion model over a wide range of axion masses.
  • This Letter reports the results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 μ eV . The search excludes the range of axion-photon couplings predicted by plausible models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume haloscope at subkelvin temperatures, thereby reducing thermal noise as well as the excess noise from the ultralow-noise superconducting quantum interference device amplifier used for the signal power readout. Finally, ongoing searches will provide nearly definitive tests of the invisible axion model over a wide range of axion masses.
  • We examine mixed axion/neutralino cold dark matter production in the SUSY DFSZ axion model where an axion superfield couples to Higgs superfields. We calculate a wide array of axino and saxion decay modes along with their decay temperatures, and thermal and non-thermal production rates. For a SUSY benchmark model with a standard underabundance (SUA) of Higgsino-like dark matter (DM), we find for the PQ scale f{sub a}∼<10{sup 12} GeV that the DM abundance is mainly comprised of axions as the saxion/axino decay occurs before the standard neutralino freeze-out and thus its abundance remains suppressed. For 10{sup 12}∼10{sup 14} GeV, bothmore » neutralino dark matter and dark radiation are typically overproduced. For judicious parameter choices, these can be suppressed and the combined neutralino/axion abundance brought into accord with measured values. A SUSY benchmark model with a standard overabundance (SOA) of bino DM is also examined and typically remains excluded due at least to too great a neutralino DM abundance for f{sub a}∼<10{sup 15} GeV. For f{sub a}∼>10{sup 15} GeV and lower saxion masses, large entropy production from saxion decay can dilute all relics and the SOA model can be allowed by all constraints.« less