Astrophysical Searches and Constraints

Marsh, David J. E.; Hoof, Sebastian

doi:10.1007/978-3-030-95852-7_3

Cited by 4 publications

(2 citation statements)

References 166 publications

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“…Axion potentials thus arise only from non-perturbative quantum effects like instantons (breaking the shift symmetry to a discrete subgroup), or if their shift symmetry gets softly and spontaneously broken. As these axion potentials remain largely protected from uncontrolled perturbative quantum corrections, axions have become candidates for driving slow-roll inflation [4], comprising (a part of) cold dark matter [5][6][7][8][9], and more recently for ultralight 'fuzzy' dark matter [10,11].…”

Section: Introductionmentioning

confidence: 99%

Axionic Festina Lente

Guidetti

Righi

Venken

et al. 2023

J. High Energ. Phys.

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The swampland conjecture known as Festina Lente (FL) imposes a lower bound on the mass of all charged particles in a quasi-de Sitter space. In this paper, we propose the aFL (axionic Festina Lente) bound, an extension of FL to axion-like particles arising from type II string theory. We find that the product of the instanton action and the axion decay constant is bounded from below by the vacuum energy. This is achieved indirectly, using dimensional reduction on Calabi-Yau threefolds, and translating the FL result for dipoles into a purely geometric bound. We discuss axionic black holes evolution, and aFL constraints on Euclidean wormholes, showing that the gravitational arguments leading to the FL bound for U(1) charged particles cannot be directly applied to axions. Moreover, we discuss phenomenological implications of the aFL bound, including constraints on string inflation models and the axion-photon coupling via kinetic mixing.

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Section: Introductionmentioning

confidence: 99%

Axionic Festina Lente

Guidetti

Righi

Venken

et al. 2023

J. High Energ. Phys.

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“…There have been seminal works on various astrophysical aspects of extended dark matter structures and star-like objects-for instance, looking at their gravitational lensing characteristics [25][26][27][28], signatures from baryonic accretion [17,26], gravitational wave signatures [29,30] and so on (For a more comprehensive survey and summary of the existing literature, in these contexts, we kindly refer the interested reader to some of the excellent current reviews and white papers [23,24,[31][32][33]).…”

Section: Introductionmentioning

confidence: 99%

Q-balls in the sky

Ansari¹,

Bhandari²,

Thalapillil³

2023

Preprint

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There may exist extended configurations in the dark matter sector that are analogues of structures in the visible sector. In this work, we explore non-topological solitonic configurations, specifically Q-balls, and study when they may form macroscopic astrophysical structures and what their distinct characteristics might be. We study in some detail theoretical bounds on their sizes and constraints on the underlying parameters, based on criteria for an astrophysical Q-ball's existence, gravitational stability and viability of solutions. Following this path, one is able to obtain novel limits on astrophysical Q-ball sizes and their underlying parameters. We also explore the gravitational lensing features of different astrophysical Q-ball profiles, which are more general than the simple thin-wall limit. It is seen that the magnification characteristics may be very distinct, depending on the actual details of the solution, even for astrophysical Q-balls having the same size and mass. Assuming that such astrophysical Q-balls may form a small component of the dark matter in the universe, we place limits on this fraction from the gravitational microlensing surveys EROS-2, OGLE-IV and the proposed future survey WFIRST. Exploring various astrophysical Q-ball profiles and sizes, it is found that while for smaller masses, the dark matter fraction comprising astrophysical Q-balls is at most sub-percent, for larger masses, it may be significantly higher.

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From inflation to quintessence: a history of the universe in string theory

Cicoli,

Cunillera,

Padilla

et al. 2024

J. High Energ. Phys.

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We present a type IIB 4D string model with stabilised moduli which is able to describe the history of the universe from inflation to quintessence. The underlying Calabi-Yau volume is controlled by two moduli which are stabilised by perturbative effects. The lighter of them drives Fibre Inflation at a large energy scale. The two associated axions are ultra-light since they are lifted only at the non-perturbative level. The lighter of them can drive quintessence if its decay constant is large enough to prevent quantum diffusion during inflation from ruining the initial conditions. The right dark energy scale can be obtained via a large suppression from poly-instanton effects. The heavier axion gives a negligible contribution to dark matter since it starts oscillating after matter-radiation equality. If instead none of the two axions has a large decay constant, a mild alignment allows the lighter axion to drive quintessence, while the heavier can be at most a few percent of dark matter due to isocurvature and UV bounds. In both cases dark matter can also come from either primordial black holes or the QCD axion.

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Astrophysical Searches and Constraints

Cited by 4 publications

References 166 publications

Axionic Festina Lente

Axionic Festina Lente

Q-balls in the sky

From inflation to quintessence: a history of the universe in string theory

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