On preheating in alpha-attractor models of inflation

Krajewski, Tomasz; Turzyński, Krzysztof; Wieczorek, Michał

doi:10.48550/arxiv.1801.01786

Cited by 14 publications

(62 citation statements)

References 38 publications

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“…These scenarios also tend to be in good agreement with the increasingly tightening experimental bounds on inflationary parameters [33]. Flattened plateau potentials are quite common and appear, for instance, in alpha-attractor models [34][35][36][37][38][39], and in Palatini formulations with non-minimal gravitational couplings [40][41][42][43][44]. Also models in [1,[45][46][47] give rise to flat potentials, but these are incapable of producing tachyonic preheating.…”

Section: Introductionsupporting

confidence: 59%

“…As these perturbations grow, interactions between the modes become increasingly important, and the remaining evolution has to be studied using non-linear methods, such as lattice simulations or thermal field theory [39,[51][52][53][54].…”

Section: General Considerationsmentioning

confidence: 99%

“…Our approach does not describe processes during the final non-linear stage of preheating, such as the creation of secondary peaks due to rescattering, formation of oscillons or the eventual thermalization of the inflaton particles. These processes have so far been studied using lattice methods [39,[51][52][53][54]. We also do not consider the decay of the fragmented inflaton into the SM thermal bath.…”

Section: Introductionmentioning

confidence: 99%

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The Linear Regime of Tachyonic Preheating

Koivunen,

Tomberg,

Veermäe

2022

Preprint

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Tachyonic preheating is realized when the inflaton repeatedly returns to a convex region of the potential during the post-inflationary oscillating phase. This will induce a strong tachyonic instability and lead to a rapid fragmentation of the coherent field that can complete within a fraction of an e-fold. In this paper, we study the linear regime of this process in a model-independent way. To this purpose, we construct simplified models that provide an analytic Floquet theoretic description of mode growth. This approach captures the essential features of well-motivated tachyonic preheating scenarios, including scenarios in which the inflaton is part of a larger scalar multiplet. We show that tachyonic preheating is efficient if the field excursions are sub-Planckian, can produce gravitational waves in the frequency range of current and future gravitational wave interferometers, and can be consistent with any experimentally allowed tensor-to-scalar ratio.

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Section: Introductionsupporting

confidence: 59%

Section: General Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Linear Regime of Tachyonic Preheating

Koivunen,

Tomberg,

Veermäe

2022

Preprint

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“…Fragmentation is very quick-the field can fragment entirely in much less than an e-fold of expansion. This conclusion is backed up by lattice computations [27][28][29][30][31]. A better understanding of the preheating phase can improve the CMB predictions of these models, predict gravitational wave (GW) signals, and inspire further model building.…”

Section: Introductionmentioning

confidence: 92%

Tachyonic Preheating in Plateau Inflation

Tomberg,

Veermäe

2021

Preprint

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Plateau inflation is an experimentally consistent framework in which the scale of inflation can be kept relatively low. Close to the edge of the plateau, scalar perturbations are subject to a strong tachyonic instability. Tachyonic preheating is realized when, after inflation, the oscillating inflaton repeatedly re-enters the plateau. We develop the analytic theory of this process and expand the linear approach by including backreaction between the coherent background and growing perturbations. For a family of plateau models, the analytic predictions are confronted with numerical estimates. Our analysis shows that the inflaton fragments in a fraction of an e-fold in all examples supporting tachyonic preheating, generalizing the results of previous similar studies. In these scenarios, the scalar-to-tensor ratio is tiny, r < 10 −7 .

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“…The post-inflationary dynamics and the effect of parametric resonance[27][28][29] is left for future work.…”

mentioning

confidence: 99%

Gravitational waves from spectator Gauge-flation

Iarygina,

Sfakianakis

2021

Preprint

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We investigate the viability of inflation with a spectator sector comprised of non-Abelian gauge fields coupled through a higher order operator. We dub this model "spectator Gaugeflation". We study the predictions for the amplitude and tensor tilt of chiral gravitational waves and conclude that a slightly red-tilded tensor power spectrum is preferredAs with related models, the enhancement of chiral gravitational waves with respect to the single-field vacuum gravitational wave background is controlled by the parameter γ = g 2 Q 2 /H 2 , where g is the gauge coupling, H is the Hubble scale and Q is the VEV of the SU (2) sector. The requirement that the SU (2) is a spectator sector leads to a maximum allowed value for γ, thereby constraining the possible amplification. In order to provide concrete predictions, we use an α-attractor T-model potential for the inflaton sector. Potential observation of chiral gravitational waves with significantly tilted tensor spectra would then indicate the presence of additional couplings of the gauge fields to axions, like in the spectator axion-SU(2) model, or additional gauge field operators.

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On preheating in alpha-attractor models of inflation

Cited by 14 publications

References 38 publications

The Linear Regime of Tachyonic Preheating

The Linear Regime of Tachyonic Preheating

Tachyonic Preheating in Plateau Inflation

Gravitational waves from spectator Gauge-flation

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