Zoology of Graviton non-Gaussianities

Cabass, Giovanni

doi:10.48550/arxiv.2103.09816

Cited by 4 publications

(7 citation statements)

References 55 publications

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“…We also compute a four-graviton diagram from graviton exchange by invoking a particularly simple interaction that is expected to appear in the Effective Field theory of Inflation [10] (see e.g. [11,12]).…”

Section: Jcap08(2021)003 1 Introductionmentioning

confidence: 99%

Cutting cosmological correlators

Goodhew

Jazayeri

Gordon

et al. 2021

J. Cosmol. Astropart. Phys.

115

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The initial conditions of our universe appear to us in the form of a classical probability distribution that we probe with cosmological observations. In the current leading paradigm, this probability distribution arises from a quantum mechanical wavefunction of the universe. Here we ask what the imprint of quantum mechanics is on the late time observables. We show that the requirement of unitary time evolution, colloquially the conservation of probabilities, fixes the analytic structure of the wavefunction and of all the cosmological correlators it encodes. In particular, we derive in perturbation theory an infinite set of single-cut rules that generalize the Cosmological Optical Theorem and relate a certain discontinuity of any tree-level n-point function to that of lower-point functions. Our rules are closely related to, but distinct from the recently derived Cosmological Cutting Rules. They follow from the choice of the Bunch-Davies vacuum and a simple property of the (bulk-to-bulk) propagator and are astoundingly general: we prove that they are valid for fields with a linear dispersion relation and any mass, any integer spin and arbitrary local interactions with any number of derivatives. They also apply to general FLRW spacetimes admitting a Bunch-Davies vacuum, including de Sitter, slow-roll inflation, power-law cosmologies and even resonant oscillations in axion monodromy. We verify the single-cut rules in a number of non-trivial examples, including four massless scalars exchanging a massive scalar, as relevant for cosmological collider physics, four gravitons exchanging a graviton, and a scalar five-point function.

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Section: Jcap08(2021)003 1 Introductionmentioning

confidence: 99%

Cutting cosmological correlators

Goodhew

Jazayeri

Gordon

et al. 2021

J. Cosmol. Astropart. Phys.

115

View full text Add to dashboard Cite

show abstract

“…where the last equality is equivalent to the first condition in (19), (3w − 1)(w + 1) = 0, which has already been taken into account in (20).…”

Section: Perfect Fluid As a Special Case Of Solidmentioning

confidence: 99%

“…Similarly as the scalar field, the solid matter can be part of the dark matter sector [14], or it can drive the inflation [15][16][17][18]. A very recent and more systematic approach generalizing the solid matter in cosmology is in [19].…”

Section: Introductionmentioning

confidence: 99%

Solid matter with zero shear modulus in flat Universe

Mészáros¹

2021

Class. Quantum Grav.

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For a perfect fluid, the quantity defined through mixed components of the stress-energy tensor w = (T i i /3)/(−T 0 0 ) is independent on the choice of coordinates only for two values of the pressure to energy density ratio w = p/ρ: for radiation with w = 1/3, and for dark energy with w = −1. With other choices of w, the quantity w is coordinate dependent, and w = w only in the local rest frame of the fluid. We show that the same is true also for solid matter with shear stress Lamé coefficient set to zero in a flat Friedmann-Lemaître-Robertson-Walker Universe with perturbed metric as well as stress-energy tensor. We call the two different solids with coordinate independent w radiation-like solid and dark energy-like solid, and we restrict ourselves to these two special cases. By analysing second order perturbations we discover two one parametric sets of such solid matter models containing special cases of radiation and dark energy as perfect fluids. We also study equations for perturbations up to the second order for both sets of models.

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“…There is no shortage of models generalizing the multifield approach even more, and among them there are models inspired by general relativistic elasticity [42] with a triplet of fields playing the same role as body coordinates of a solid. Such concept of matter has been studied in general cosmological context [43][44][45][46], but mostly as the inflationary model [47][48][49][50][51] with broad further development [52][53][54][55][56][57][58][59].…”

Section: Introductionmentioning

confidence: 99%

“…The model studied in this paper differs from other works with similar forms of the matter Lagrangian. Unlike in works focused on cosmic inflation [47][48][49][50][51][52][53][54][55][56][57][58][59], we allow the pressure to energy density ration to be significantly different from w = −1. In other works dealing with the solid matter in the more general cosmological context [43][44][45][46] there is matter Lagrangian in the form of the Taylor expansion in the terms of traces of the body metric…”

Section: Introductionmentioning

confidence: 99%

Evolution of perturbations in a universe with exotic solid-like matter

Mészáros¹

2023

Preprint

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We study cosmological perturbations in a universe with only one matter component described by a triplet of fields. Configuration of these fields is the same as for body coordinates of a solid, and they enter the matter Lagrangian only through the kinetic term. We restrict ourselves only to cases with constant pressure to energy density ratio w. Superhorizon perturbations have no constant modes with scalar vector and tensor perturbations decaying or growing at different rates, and in cases with pressure to energy density ratio w > (19 − 8 √ 7)/3 = = − 0.722 perturbations propagate with superluminal sound speed. Regarding our universe, these results illustrate possible challenges with comparing the observational data to models similar to solid inflation, if the inflation is followed by a period during which the studied model is a sufficiently good approximation.

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Zoology of Graviton non-Gaussianities

Cited by 4 publications

References 55 publications

Cutting cosmological correlators

Cutting cosmological correlators

Solid matter with zero shear modulus in flat Universe

Evolution of perturbations in a universe with exotic solid-like matter

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