Observational constraints on warm natural inflation

Montefalcone, Gabriele; Aragam, Vikas; Visinelli, Luca; Freese, Katherine

doi:10.1088/1475-7516/2023/03/002

Cited by 16 publications

(6 citation statements)

References 64 publications

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“…These symmetry properties also suppress radiative and thermal corrections which allow this model and more generally axion-like potentials to be trivially implemented in the context of WI [43,[74][75][76]. This potential in the WI scenario was found to be consistent with observations for super-Planckian and marginal sub-Planckian values for the decay constant f [55,77].…”

Section: Jcap01(2024)032supporting

confidence: 60%

“…This module then determines the best fitting function G(Q) via the method of least squares. Specifically, to allow for a direct comparison with previous work, we employ the polynomial fitting functions most prominently used in the literature due to its simplicity [50,55,68,84]:…”

Section: Scalar_dissipation_functionmentioning

confidence: 99%

“…Although we do not specify g * (T ) in the equations, we adopt the number of relativistic degrees of freedom in the minimal supersymmetric Standard Model g * (T ) = 228.75 when presenting our results 4. In some of the WI literature (including our own previous paper[55]), the slow-roll (SR) parameters are defined somewhat differently, namely as the quantities in the equation here divided by a factor (1 + Q). With these alternate definitions, the slow-roll conditions are satisfied instead for SR parameters ≪ 1.…”

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confidence: 99%

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WarmSPy: a numerical study of cosmological perturbations in warm inflation

Montefalcone,

Aragam,

Visinelli

et al. 2024

J. Cosmol. Astropart. Phys.

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We present WarmSPy, a numerical code in Python designed to solve for the perturbations' equations in warm inflation models and compute the corresponding scalar power spectrum at CMB horizon crossing. In models of warm inflation, a radiation bath of temperature T during inflation induces a dissipation (friction) rate of strength Q ∝ Tc /ϕm in the equation of motion for the inflaton field ϕ. While for a temperature-independent dissipation rate (c = 0) an analytic expression for the scalar power spectrum exists, in the case of a non-zero value for c the set of equations can only be solved numerically. For c > 0 (c < 0), the coupling between the perturbations in the inflaton field and radiation induces a growing (decaying) mode in the scalar perturbations, generally parameterized by a multiplicative function G(Q) which we refer to as the scalar dissipation function. Using WarmSPy, we provide an analytic fit for G(Q) for the cases of c = {3,1,-1}, corresponding to three cases that have been realized in physical models. Compared to previous literature results, our fits are more robust and valid over a broader range of dissipation strengths Q ∈ [10-7,104]. Additionally, for the first time, we numerically assess the stability of the scalar dissipation function against various model parameters, inflationary histories as well as the effects of metric perturbations. As a whole, the results do not depend appreciably on most of the parameters in the analysis, except for the dissipation index c, providing evidence for the universal behaviour of the scalar dissipation function G(Q).

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Section: Jcap01(2024)032supporting

confidence: 60%

Section: Scalar_dissipation_functionmentioning

confidence: 99%

mentioning

confidence: 99%

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WarmSPy: a numerical study of cosmological perturbations in warm inflation

Montefalcone,

Aragam,

Visinelli

et al. 2024

J. Cosmol. Astropart. Phys.

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“…This difference is significant in the case of strong dissipation (Q ≫ 1), and particularly for b G ≥ 0, which corresponds to a dissipation rate with a non-negative temperature dependence. For example, if we set Q = 100 and b G = 6.52, which corresponds to the value found for a dissipation rate Υ ∝ T c , with c = 3 [50], we obtain…”

Section: Jcap02(2024)006mentioning

confidence: 71%

Defying eternal inflation in warm inflation with a negative running

Montefalcone,

Ramos,

Vicente

et al. 2024

J. Cosmol. Astropart. Phys.

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It was pointed out previously [1] that a sufficiently negative running of the spectral index of curvature perturbations from (ordinary i.e. cold) inflation is able to prevent eternal inflation from ever occurring. Here, we reevaluate those original results, but in the context of warm inflation, in which a substantial radiation component (produced by the inflaton) exists throughout the inflationary period. We demonstrate that the same general requirements found in the context of ordinary (cold) inflation also hold true in warm inflation; indeed an even tinier amount of negative running is sufficient to prevent eternal inflation. This is particularly pertinent, as models featuring negative running are more generic in warm inflation scenarios. Finally, the condition for the existence of eternal inflation in cold inflation — that the curvature perturbation amplitude exceed unity on superhorizon scales — becomes more restrictive in the case of warm inflation. The curvature perturbations must be even larger, i.e. even farther out on the potential, away from the part of the potential where observables, e.g. in the Cosmic Microwave Background, are produced.

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“…Recently, a new fit for the function G(Q) was found in[76], also for a cubic dissipation coefficient. We have considered this fit for the βexponential model and found that the difference in the results is minimal, so our conclusions for the model are unchanged.…”

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confidence: 99%

Warm $$\beta $$-exponential inflation and the swampland conjectures

et al. 2023

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We investigate theoretical and observational aspects of a warm inflation scenario driven by the $$\beta $$ β -exponential potential, which generalizes the well-known power law inflation. In such a scenario, the decay of the inflaton field into radiation happens during the inflationary phase. In our study, we consider a dissipation coefficient ($$\varGamma $$ Γ ) with cubic dependence on the temperature (T) and investigate the consequences in the inflationary dynamics, focusing on the impact on the spectral index $$n_s$$ n s , its running $$n_{run}$$ n run and tensor-to-scalar ratio r. We find it possible to realize inflation in agreement with current cosmic microwave background data in weak and strong dissipation regimes. We also investigate theoretical aspects of the model in light of the swampland conjectures, as warm inflation in the strong dissipation regime has been known as a way to satisfy the three conditions currently discussed in the literature. We find that when $$\varGamma \propto T^3$$ Γ ∝ T 3 , the $$\beta $$ β -exponential model can be accommodated into the conjectures.

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Observational constraints on warm natural inflation

Cited by 16 publications

References 64 publications

WarmSPy: a numerical study of cosmological perturbations in warm inflation

WarmSPy: a numerical study of cosmological perturbations in warm inflation

Defying eternal inflation in warm inflation with a negative running

Warm $$\beta $$-exponential inflation and the swampland conjectures

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