Low-scale inflation

Germán, Gabriel; Ross, Graham G.; Sarkar, S.

doi:10.1016/s0550-3213(01)00258-9

Cited by 101 publications

(113 citation statements)

References 57 publications

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“…This inflationary scale is not excluded, see [57,58] but rather low. However, we have not studied the evolution of vector perturbation during the radiation era.…”

mentioning

confidence: 99%

Inflationary perturbations in bimetric gravity

Cusin¹,

Durrer²,

Guarato³

et al. 2015

J. Cosmol. Astropart. Phys.

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In this paper we study the generation of primordial perturbations in a cosmological setting of bigravity during inflation. We consider a model of bigravity which can reproduce the ΛCDM background and large scale structure and a simple model of inflation with a single scalar field and a quadratic potential. Reheating is implemented with a toy-model in which the energy density of the inflaton is entirely dissipated into radiation. We present analytic and numerical results for the evolution of primordial perturbations in this cosmological setting. We find that the amplitude of tensor perturbations generated during inflation is sufficiently suppressed to avoid the effects of the tensor instability discovered in Refs. [1,2] which develops during the cosmological evolution in the physical sector. We argue that from a pure analysis of the tensor perturbations this bigravity model is compatible with present observations. However, we derive rather stringent limits on inflation from the vector and scalar sectors.

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“…This inflationary scale is not excluded, see [57,58] but rather low. However, we have not studied the evolution of vector perturbation during the radiation era.…”

mentioning

confidence: 99%

Inflationary perturbations in bimetric gravity

Cusin¹,

Durrer²,

Guarato³

et al. 2015

J. Cosmol. Astropart. Phys.

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“…Such an inflaton potential is commonly assumed in the analysis of non-oscillating models [20,21] and means that the problem of the details of the inflationary dynamics factorises from the details of the reheating, the latter of which is our primary interest in this work. Many suitable inflationary potentials are possible, for example a hill-top potential [50]. Between the inflating and reheating eras, the potential energy of the system is converted to inflaton kinetic energy, and the details of the inflaton potential that achieves this does not have a significant impact on the system's subsequent dynamics, assuming that this occurs before reheating becomes significant.…”

Section: Jhep11(2017)125mentioning

confidence: 99%

Non-perturbative reheating and Nnaturalness

Hardy¹

2017

J. High Energ. Phys.

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We study models in which reheating happens only through non-perturbative processes. The energy transferred can be exponentially suppressed unless the inflaton is coupled to a particle with a parametrically small mass. Additionally, in some models a light scalar with a negative mass squared parameter leads to much more efficient reheating than one with a positive mass squared of the same magnitude. If a theory contains many sectors similar to the Standard Model coupled to the inflaton via their Higgses, such dynamics can realise the Nnaturalness solution to the hierarchy problem. A sector containing a light Higgs with a non-zero vacuum expectation value is dominantly reheated and there is little energy transferred to the other sectors, consistent with cosmological constraints. The inflaton must decouple from other particles and have a flat potential at large field values, in which case the visible sector UV cutoff can be raised to 10 TeV in a simple model.

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“…Inflation is associated with a scalar field, the "inflaton", and the energy scale at which inflation occurs is typically of the order of E I = 10 16 GeV [1] but it is possible to have consistent inflationary models with E I as low as O(100)M eV [5]. On the other hand Dark Matter is described by an energy density which redshifts as ρ dm ∼ a(t) −3 and is described by particles where its mass m ≫ T , with T its temperature.…”

Section: Introductionmentioning

confidence: 99%

Dark Matter from the inflaton field

Macorra

2012

Astroparticle Physics

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We present a model where inflation and Dark Matter takes place via a single scalar field φ. Without introducing any new parameters we are able unify inflation and Dark Matter using a scalar field φ that accounts for inflation at an early epoch while it gives a Dark Matter WIMP particle at low energies. After inflation our universe must be reheated and we must have a long period of radiation dominated before the epoch of Dark Matter. Typically the inflaton decays while it oscillates around the minimum of its potential. If the inflaton decay is not complete or sufficient then the remaining energy density of the inflaton after reheating must be fine tuned to give the correct amount of Dark Matter. An essential feature here, is that Dark Matter-Inflaton particle is produced at low energies without fine tuning or new parameters. This process uses the same coupling g as for the inflaton decay. Once the field φ becomes non-relativistic it will decouple as any WIMP particle, since n φ is exponentially suppressed. The correct amount of Dark Matter determines the cross section and we have a constraint between the coupling g and the mass mo of φ. The unification scheme we present here has four free parameters, two for the scalar potential V (φ) given by the inflation parameter λ of the quartic term and the mass mo. The other two parameters are the coupling g between the inflaton φ and a scalar filed ϕ and the coupling h between ϕ with standard model particles ψ or χ. These four parameters are already present in models of inflation and reheating process, without considering Dark Matter. Therefore, our unification scheme does not increase the number of parameters and it accomplishes the desired unification between the inflaton and Dark Matter for free.

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Low-scale inflation

Cited by 101 publications

References 57 publications

Inflationary perturbations in bimetric gravity

Inflationary perturbations in bimetric gravity

Non-perturbative reheating and Nnaturalness

Dark Matter from the inflaton field

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