String theoretic QCD axions in the light of PLANCK and BICEP2

Choi, Kiwoon; Jeong, Kwang Sik; Seo, Min-Seok

doi:10.1007/jhep07(2014)092

Cited by 25 publications

(17 citation statements)

References 89 publications

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“…However, the above constraints only apply when the PQ field Φ has the vacuum expectation value v(= F a N DW ) during inflation. As first pointed out by Linde [20,22,23,24,25], when the PQ field has a larger expectation value, the isocurvature perturbations are suppressed. The constraints are the most relaxed when the PQ field takes the Planck scale M p ( 2.4 × 10 18 GeV) during inflation.…”

Section: Isocuravture Perturbationsmentioning

confidence: 87%

Cosmologically allowed regions for the axion decay constant F

2018

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If the Peccei-Quinn symmetry is already broken during inflation, the decay constant F a of the axion can be in a wide region from 10 11 GeV to 10 18 GeV for the axion being the dominant dark matter. In this case, however, the axion causes the serious cosmological problem, isocurvature perturbation problem, which severely constrains the Hubble parameter during inflation. To avoid this problem, Peccei-Quinn scalar field must take a large value ∼ M p (Planck scale) during inflation. In this letter, we point out that the allowed region of the decay constant F a is reduced to a rather narrow region for a given tensor-to-scalar ratio r when Peccei-Quinn scalar field takes ∼ M p during inflation. For example, if the ratio r is determined as r 10 −3 in future measurements, we can predict F a (0.1 − 1.4) × 10 12 GeV for domain wall number N DW = 6.

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Section: Isocuravture Perturbationsmentioning

confidence: 87%

Cosmologically allowed regions for the axion decay constant F

2018

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“…For a given K and N , we plot in black contours the maximal allowed value of f a ≡ √ 2v a such that the contributions to the axion mass today due to explicit breaking do not disrupt the solution to the strong CP problem-i.e., both N and KN are sufficiently large that the U (1) PQ -breaking operators of Eq. (38) give small contributions to m 2 eff . As above, we implement strong CP 18 The quartic term can be neglected for λS 19 Similarly, we neglect terms such as |S| 2 S 2 .…”

Section: Additional U (1)pq Fieldsmentioning

confidence: 92%

“…Today, when |I| = 0 is assumed, vS ,0 = 0 is driven by the tadpole forS induced via the first term of Eq. (38) when v S,0 f S √ 2 . For instance, neglecting the terms with powers ofS greater than two, 18 The modification to the PQ potential required to enhance vS during inflation still risks destabilizing the inflaton potential.…”

Section: Additional U (1)pq Fieldsmentioning

confidence: 99%

High-scale axions without isocurvature from inflationary dynamics

2016

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Observable primordial tensor modes in the cosmic microwave background (CMB) would point to a high scale of inflation HI . If the scale of Peccei-Quinn (PQ) breaking fa is greater than, CMB constraints on isocurvature naïvely rule out QCD axion dark matter. This assumes the potential of the axion is unmodified during inflation. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed. We find that models that rely solely on a larger PQ-breaking scale during inflation fI require either late-time dilution of the axion abundance or highly super-Planckian fI that somehow does not dominate the inflationary energy density. Models that have enhanced explicit breaking of the PQ symmetry during inflation may allow fa close to the Planck scale. Avoiding disruption of inflationary dynamics provides important limits on the parameter space.

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“…See also refs. [92][93][94] for recent discussion in this direction. The saxion coherent oscillation with an amplitude of ∼ f a remains in this case, but it is not cosmologically problematic [66].…”

Section: Jhep11(2014)151mentioning

confidence: 99%

Axion models with high scale inflation

Moroi

Mukaida

Nakayama

et al. 2014

J. High Energ. Phys.

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Abstract:We revisit the cosmological aspects of axion models. In the high-scale inflation scenario, the Peccei-Quinn (PQ) symmetry is likely to be restored during/after inflation. If the curvature of the PQ scalar potential at the origin is smaller than its vacuum expectation value; for instance in a class of SUSY axion models, thermal inflation happens before the radial component of the PQ scalar (saxion) relaxes into the global minimum of the potential and the decay of saxion coherent oscillation would produce too much axion dark radiation. In this paper, we study how to avoid the overproduction of axion dark radiation with some concrete examples. We show that, by taking account of the finite-temperature dissipation effect appropriately, the overproduction constraint can be relaxed since the PQ scalar can take part in the thermal plasma again even after the PQ phase transition. We also show that it can be further relaxed owing to the late time decay of another heavy CP-odd scalar, if it is present.

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String theoretic QCD axions in the light of PLANCK and BICEP2

Cited by 25 publications

References 89 publications

Cosmologically allowed regions for the axion decay constant F

Cosmologically allowed regions for the axion decay constant F

High-scale axions without isocurvature from inflationary dynamics

Axion models with high scale inflation

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