Acoustic misalignment mechanism for axion dark matter

Abstract A rotation in the field space of a complex scalar field corresponds to a Bose-Einstein condensation of U(1) charges. We point out that fluctuations in this rotating condensate exhibit sound-wave modes, which can be excited by cosmic perturbations and identified with axion fluctuations once...

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Main Authors: Arushi Bodas, Raymond T. Co, Akshay Ghalsasi, Keisuke Harigaya, Lian-Tao Wang
Format: Article
Language:English
Published: SpringerOpen 2025-08-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP08(2025)131
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author Arushi Bodas
Raymond T. Co
Akshay Ghalsasi
Keisuke Harigaya
Lian-Tao Wang
author_facet Arushi Bodas
Raymond T. Co
Akshay Ghalsasi
Keisuke Harigaya
Lian-Tao Wang
author_sort Arushi Bodas
collection DOAJ
description Abstract A rotation in the field space of a complex scalar field corresponds to a Bose-Einstein condensation of U(1) charges. We point out that fluctuations in this rotating condensate exhibit sound-wave modes, which can be excited by cosmic perturbations and identified with axion fluctuations once the U(1) charge condensate has been sufficiently diluted by cosmic expansion. We consider the possibility that these axion fluctuations constitute dark matter and develop a formalism to compute its abundance. We carefully account for the growth of fluctuations during the epoch where the complex scalar field rotates on the body of the potential and possible nonlinear evolution when the fluctuations become non-relativistic. We find that the resultant dark matter abundance can exceed the conventional and kinetic misalignment contributions if the radial direction of the complex scalar field is sufficiently heavy. The axion dark matter may also be warm enough to leave imprints on structure formation. We discuss the implications of this novel dark matter production mechanism — acoustic misalignment mechanism — for the axion rotation cosmology, including kination domination and baryogenesis from axion rotation, as well as for axion searches.
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institution Kabale University
issn 1029-8479
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series Journal of High Energy Physics
spelling doaj-art-a1a1dce6badd43dcb90287b69ad471b22025-08-24T11:05:10ZengSpringerOpenJournal of High Energy Physics1029-84792025-08-012025814010.1007/JHEP08(2025)131Acoustic misalignment mechanism for axion dark matterArushi Bodas0Raymond T. Co1Akshay Ghalsasi2Keisuke Harigaya3Lian-Tao Wang4Department of Physics, University of ChicagoPhysics Department, Indiana UniversityJefferson Physical Laboratory, Harvard UniversityDepartment of Physics, University of ChicagoDepartment of Physics, University of ChicagoAbstract A rotation in the field space of a complex scalar field corresponds to a Bose-Einstein condensation of U(1) charges. We point out that fluctuations in this rotating condensate exhibit sound-wave modes, which can be excited by cosmic perturbations and identified with axion fluctuations once the U(1) charge condensate has been sufficiently diluted by cosmic expansion. We consider the possibility that these axion fluctuations constitute dark matter and develop a formalism to compute its abundance. We carefully account for the growth of fluctuations during the epoch where the complex scalar field rotates on the body of the potential and possible nonlinear evolution when the fluctuations become non-relativistic. We find that the resultant dark matter abundance can exceed the conventional and kinetic misalignment contributions if the radial direction of the complex scalar field is sufficiently heavy. The axion dark matter may also be warm enough to leave imprints on structure formation. We discuss the implications of this novel dark matter production mechanism — acoustic misalignment mechanism — for the axion rotation cosmology, including kination domination and baryogenesis from axion rotation, as well as for axion searches.https://doi.org/10.1007/JHEP08(2025)131Cosmology of Theories BSMEarly Universe Particle PhysicsAxions and ALPsBaryo-and Leptogenesis
spellingShingle Arushi Bodas
Raymond T. Co
Akshay Ghalsasi
Keisuke Harigaya
Lian-Tao Wang
Acoustic misalignment mechanism for axion dark matter
Journal of High Energy Physics
Cosmology of Theories BSM
Early Universe Particle Physics
Axions and ALPs
Baryo-and Leptogenesis
title Acoustic misalignment mechanism for axion dark matter
title_full Acoustic misalignment mechanism for axion dark matter
title_fullStr Acoustic misalignment mechanism for axion dark matter
title_full_unstemmed Acoustic misalignment mechanism for axion dark matter
title_short Acoustic misalignment mechanism for axion dark matter
title_sort acoustic misalignment mechanism for axion dark matter
topic Cosmology of Theories BSM
Early Universe Particle Physics
Axions and ALPs
Baryo-and Leptogenesis
url https://doi.org/10.1007/JHEP08(2025)131
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AT akshayghalsasi acousticmisalignmentmechanismforaxiondarkmatter
AT keisukeharigaya acousticmisalignmentmechanismforaxiondarkmatter
AT liantaowang acousticmisalignmentmechanismforaxiondarkmatter