Symmetry breaking patterns for inflation

Klein, Remko; Roest, Diederik; Stefanyszyn, David

doi:10.1007/jhep06(2018)006

Cited by 5 publications

(4 citation statements)

References 107 publications

(176 reference statements)

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“…While the details of a relevant project will be presented in a future paper [67], here let us look at two simplest cases of coset space with nontrivial geometries which have been considered before in refs. [68,69]. • SO(3)/SO(2).…”

Section: A Concrete Example: Inflation In Coset Spacementioning

confidence: 99%

On the inflationary massive field with a curved field manifold

Wang

2020

J. Cosmol. Astropart. Phys.

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Massive fields during inflation provide an interesting opportunity to test new physics at very high energy scales. Meanwhile in fundamental realizations, the inflationary field space typically has a curved geometry, which may leave detectable imprints in primordial observables. In this paper we study an extension of quasi-single field inflation where the inflaton and the massive field belong to a curved field manifold. Because of the nontrivial field space curvature, the massive field here can get significant mass corrections of order the Hubble scale, thus the quasi-single field predictions on primordial non-Gaussianity are affected. We derive the same result in an equivalent approach by using the background effective field theory of inflation, where a dimension-6 operator is identified to play an important role and its cutoff scale is associated with the curvature scale of the field space. In addition, due to the slow-roll evolution of the inflaton, this type of mass correction has intrinsic time-dependence. Consequently, the running mass modifies the scaling behaviour in the squeezed limit of the scalar bispectrum, while the resulting running index measures the curvature of the internal field space. Therefore the minimal setup of a massive field within curved field space during inflation may naturally lead to new observational signatures of the field space geometry.

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Section: A Concrete Example: Inflation In Coset Spacementioning

confidence: 99%

On the inflationary massive field with a curved field manifold

Wang

2020

J. Cosmol. Astropart. Phys.

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“…We restrict ourselves to theories that contain at most two derivatives of the fields, such that the particle spectrum comprises only healthy degrees of freedom. In addition, we are interested only in models whose Einstein-frame target manifold is maximally symmetric during inflation and, more precisely, globally hyperbolic [50,73]. 6 Moreover, we require the equations of motion governing the dynamics of the theories under consideration to admit Minkowski, de Sitter and anti de Sitter vacuum solutions, since these might be essential for the eventual quantization of the theory.…”

Section: Introductionmentioning

confidence: 99%

Scale-invariant alternatives to general relativity. III. The inflation-dark energy connection

et al. 2019

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We discuss the cosmological phenomenology of biscalar-tensor models displaying a maximally symmetric Einstein-frame kinetic sector and constructed on the basis of scale symmetry and volume-preserving diffeomorphisms. These theories contain a single dimensionful parameter Λ 0 -associated with the invariance under the aforementioned restricted coordinate transformations-and a massless dilaton field. At large field values these scenarios lead to inflation with no generation of isocurvature perturbations. The corresponding predictions depend only on two dimensionless parameters, which characterize the curvature of the field-manifold and the leading order behavior of the inflationary potential. For Λ 0 = 0 the scale symmetry is unbroken and the dilaton admits only derivative couplings to matter, evading all fifth force constraints. For Λ 0 = 0 the field acquires a run-away potential that can support a dark energy dominated era at late times. We confront a minimalistic realization of this appealing framework with observations using a Markov-Chain-Monte-Carlo approach, with likelihoods from present BAO, SNIa and CMB data. A Bayesian model comparison indicates a preference for the considered model over ΛCDM, under certain assumptions for the priors. The impact of possible consistency relations among the early and late Universe dynamics that can appear within this setting is discussed with the use of correlation matrices. The results indicate that a precise determination of the inflationary observables and the dark energy equation-of-state could significantly constrain the model parameters.

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“…From Eqs. (26) and (27) we see that the minima will be at a large (super-Planckian) value if ι 1. In this case, inflation will be long (the total number of e-foldings N tot will be much larger than the required 60) and these models are large field inflationary models.…”

Section: Resultsmentioning

confidence: 78%

Inflation as a spontaneous symmetry breaking of Weyl symmetry

Barnaveli

Lucat

Prokopec

2019

J. Cosmol. Astropart. Phys.

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In this paper we study a novel realization of inflation, based on Weyl invariant gravity with torsion.We show that requiring the classical action for the scalar field to be Weyl invariant introduces a dilaton which induces a non trivial modification of the field space geometry of the scalar sector, which allows for inflationary phase that begins at the conformal point of the inflaton ψ, i.e. ψ = 0. Since the model is Weyl invariant, the inflaton condensation models a process of spontaneous Weyl symmetry breaking. For a wide range of parameters the spectral observables of the model are in good agreement with the CMB measurements, such that the scalar spectral index and the tensor-to-scalar ratio approximately agree with those of Starobinsky's inflation, i.e. n s 0.96 − 0.97 and r ≈ 3 × 10 −3 . The simplest version of our model contains two scalar degrees of freedom, one of them being an exactly flat direction. If that degree is excited early on in inflation and if inflation lasts for about 60 e-foldings, we find that the Unverse undergoes a short period of kination that predates inflation. Such a period strongly suppresses the amplitude of large scale CMB temperature fluctuations providing thus an elegant explanation for the lack of power in the lowest CMB multipoles.

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Symmetry breaking patterns for inflation

Cited by 5 publications

References 107 publications

On the inflationary massive field with a curved field manifold

On the inflationary massive field with a curved field manifold

Scale-invariant alternatives to general relativity. III. The inflation-dark energy connection

Inflation as a spontaneous symmetry breaking of Weyl symmetry

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