Comprehensive analysis of the simplest curvaton model

Byrnes, Christian T.; Cortês, Marina; Liddle, Andrew R.

doi:10.1103/physrevd.90.023523

Cited by 39 publications

(52 citation statements)

References 58 publications

(85 reference statements)

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“…The important point to note here is that n s and r T S depend only on the ratio, R, not the mechanism by which the curvaton, or curvaton-like field, sources the final curvature perturbation. This places tight constraints on the values that α, σ min and hence f (σ) can take according to the latest Planck data [41]. We soon find ourselves with a spectral index approaching 0.98 -as in the pure curvaton limit -as R becomes large with relatively small changes in f .…”

Section: Resultsmentioning

confidence: 70%

Stabilizing the Planck mass shortly after inflation

2015

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We consider a model of the early universe which consists of two scalar fields: the inflaton, and a second field which drives the stabilisation of the Planck mass (or gravitational constant). We show that the non-minimal coupling of this second field to the Ricci scalar sources a non-adiabatic pressure perturbation. By performing a fully numerical calculation we find, in turn, that this boosts the amplitude of the primordial power spectrum after inflation.

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Section: Resultsmentioning

confidence: 70%

Stabilizing the Planck mass shortly after inflation

2015

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“…We follow the notation and methods of our previous paper [8], and here just summarize the main equations. The inflaton field is denoted φ and the curvaton field σ, with potential…”

Section: Evolution and Perturbationsmentioning

confidence: 99%

“…We can phenomenologically represent the decay into the thermal bath via decay rates Γ φ and Γ σ . Hence the model so far possesses five adjustable parameters, which was the model space investigated in our earlier paper [8]. This paper will add a branching ratio f for inflaton-to-curvaton decays.…”

Section: Evolution and Perturbationsmentioning

confidence: 99%

“…Once parameter values are chosen the relevant scale can be computed, fixing φ * and N * , as shown in Ref. [8] and subsequently explored in detail in Refs. [10,11].…”

Section: Evolution and Perturbationsmentioning

confidence: 99%

“…[5] for earlier related ideas), and hence there is considerable interest in assessing how viable the curvaton model is against observations. This has been the topic of a number of recent papers [6][7][8][9][10][11]. These have tested a wide regime of model space, including cases where the observed perturbations come from a mixture of inflaton and curvaton perturbations that feed into the perturbed thermalized Universe after each field has decayed [12].…”

Section: Introductionmentioning

confidence: 99%

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Curvaton scenarios with inflaton decays into curvatons

2016

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We consider the possible decay of the inflaton into curvaton particles during reheating and analyse its effect on curvaton scenarios. Typical decay curvatons are initially relativistic then become nonrelativistic, changing the background history of the Universe. We show that this change to the background is the only way in which observational predictions of the scenario are modified. Moreover, once the required amplitude of perturbations is fixed by observation there are no signatures of such decays in other cosmological observables. The decay curvatons can prevent the Universe from becoming dominated by the curvaton condensate, making it impossible to match observations in parts of parameter space. This constrains the branching ratio of the inflaton to curvaton to be less than of order 0.1 typically. If the branching ratio is below about 10 −4 it has negligible impact on the model parameter space and can be ignored.

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Primordial non-Gaussianity as a probe of seesaw and leptogenesis

Fong,

Ghoshal,

Naskar

et al. 2023

J. High Energ. Phys.

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We present the possibility that the seesaw mechanism and nonthermal leptogenesis can be investigated via primordial non-Gaussianities in the context of a majoron curvaton model. Originating as a massless Nambu-Goldstone boson from the spontaneous breaking of the global baryon (B) minus lepton (L) number symmetry at a scale vB−L, majoron becomes massive when it couples to a new confining sector through anomaly. Acting as a curvaton, majoron produces the observed red-tilted curvature power spectrum without relying on any inflaton contribution, and its decay in the post-inflationary era gives rise to a nonthermal population of right-handed neutrinos that participate in leptogenesis. A distinctive feature of the mechanism is the generation of observable non-Gaussianity, in the parameter space where the red-tilted power spectrum and sufficient baryon asymmetry are produced. We find that the non-Gaussianity parameter fNL ≳ $$ \mathcal{O} $$ O (0.1) is produced for high-scale seesaw (vB−L at $$ \mathcal{O} $$ O (1014−17) GeV) and leptogenesis (M1 ≳ $$ \mathcal{O} $$ O (106) GeV) where the latter represents the lightest right-handed neutrino mass. While the current bounds on local non-Gaussianity excludes some part of parameter space, the rest can be fully probed by future experiments like CMB-S4, LSST, and 21 cm tomography.

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Comprehensive analysis of the simplest curvaton model

Cited by 39 publications

References 58 publications

Stabilizing the Planck mass shortly after inflation

Stabilizing the Planck mass shortly after inflation

Curvaton scenarios with inflaton decays into curvatons

Primordial non-Gaussianity as a probe of seesaw and leptogenesis

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