Perturbations in generalized multi-field inflation

Langlois, David; Renaux‐Petel, Sébastien

doi:10.1088/1475-7516/2008/04/017

Cited by 215 publications

(288 citation statements)

References 51 publications

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“…They first appeared in the socalled K-inflation models [155,156], for other studies of kinetic-driven inflation, see [426][427][428][429] and for discussion of non-Gaussianity in these models, see [430][431][432][433][434][435][436][437][438][439][440][441][442]. Models with non-canonical kinetic structure have also been much studied for cosmic acceleration, where they go by the name K-essence .…”

Section: Kinetic Screeningmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Kinetic Screeningmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…Including these effects leads to multi-field models of DBI inflation, 43 whose phenomenology has been studied comprehensively in [724][725][726][727][728][729][730]. When one or more of the angular fields are light during inflation, their quantum fluctuations lead to entropy perturbations, which propagate with the same speed of sound c s as the adiabatic mode.…”

Section: Phenomenologymentioning

confidence: 99%

Inflation and String Theory

2015

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“…(20) has been used to relate the inflaton fluctuation to the overall curvature perturbation. In the pure curvaton limit (f 2 (σ) → ∞ and thus λ 1), the isocurvature contribution is too large and has long since been ruled out [35].…”

Section: B Isocurvature Modesmentioning

confidence: 99%

Optimizing future experimental probes of inflation

Easson

Powell

2011

Phys. Rev. D

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The discovery of many novel realizations of the inflationary universe paradigm has led to a degeneracy problem: many different inflationary Lagrangians generate the same perturbation spectra. Resolving this problem requires the future discovery of additional observables, beyond the scalar adiabatic and tensor two-point functions on CMB scales. One important source of degeneracy arises in models where the density perturbation is generated by a non-inflationary degree of freedom, for example, through curvatons or modulated reheating. We consider the curvaton scenario as representative of this class, and analyze the degeneracy with single field, canonical inflation that results if the curvaton goes undetected by future observations. We perform Monte Carlo potential reconstructions in the absence of distinguishing observables, such as non-Gaussiantities or isocurvature modes. The resulting degeneracy is considerable and the improved measurements of spectral parameters from future probes like CMBPol, offer little to better the situation. Given a degeneracy-breaking observation, the observables must still be inverted to obtain the inflationary potential, with different observations resulting in reconstructions of varying quality. We find that a future detection of isocurvature modes or a precision measurement of the tensor spectral index will enable the most successful reconstructions in the presence of curvatons.

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Perturbations in generalized multi-field inflation

Cited by 215 publications

References 51 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Inflation and String Theory

Optimizing future experimental probes of inflation

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