Non-Gaussianity as a particle detector

Lee, Hayden; Baumann, Daniel; Pimentel, Guilherme L.

doi:10.1007/jhep12(2016)040

Cited by 229 publications

(379 citation statements)

References 73 publications

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“…(See also refs. [22][23][24][25].) Our study provides the conditions for the absence of such an imprint made after the Hubble crossing time of the comoving scale of our interest during inflation.…”

Section: Jhep10(2017)127mentioning

confidence: 82%

Large gauge transformation, soft theorem, and Infrared divergence in inflationary spacetime

Tanaka

Urakawa

2017

J. High Energ. Phys.

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It is widely known that the primordial curvature perturbation ζ has several universal properties in the infrared (IR) such as the soft theorem, which is also known as the consistency relation, and the conservation in time. They are valid in rather general single clock models of inflation. It has been argued that these universal properties are deeply related to the large gauge transformations in inflationary spacetime. However, the invariance under the large gauge transformations is not sufficient to show these IR properties. In this paper, we show that the locality condition is crucial to show the consistency relation and the conservation of ζ. This argument also can apply to an interacting system with the inflaton and heavy fields which have arbitrary integer spins, including higher spin fields, which may be motivated from string theory. We will also show that the locality condition guarantees the cancellation of the IR divergences in a certain class of variables whose correlation functions resemble cosmologically observable quantities.

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Section: Jhep10(2017)127mentioning

confidence: 82%

Large gauge transformation, soft theorem, and Infrared divergence in inflationary spacetime

Tanaka

Urakawa

2017

J. High Energ. Phys.

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“…The above minimal case geometrically means that the inflaton trajectory is strictly straight in the field space landscape, and realistically we expect some level of bending of the trajectory that naturally introduces direct couplings between the inflaton and heavy fields [2,3,7,29]. There can also be other types of direct couplings that may not be easily visualized geometrically [3].…”

Section: E Implications For Inflation Modelsmentioning

confidence: 99%

“…Because heavy fields do not respect any slow-roll conditions, their self-interactions are potential sources of large non-linearities [2,3,29]. This introduces diagrams such as B in Fig.…”

Section: E Implications For Inflation Modelsmentioning

confidence: 99%

“…These constraints will be extended to those including the CMB B-modes sourced by tensor non-Gaussianities [29,32] and a more exhaustive search will be performed to include recently-developed models (e.g. [24,33]).…”

Section: Introductionmentioning

confidence: 99%

“…The possible amplitudes of these bispectra span a wide range of values, and strongly depend on the nature of couplings in the model [2,3,20,29]. It is the purpose of this paper to investigate what sizes of the bispectrum may be measurable and the detectability of heavy particles in the futurist 21-cm experiments.…”

Section: Introductionmentioning

confidence: 99%

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Prospects for cosmological collider physics

Meerburg

Münchmeyer

Muñoz

et al. 2017

J. Cosmol. Astropart. Phys.

104

120

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It is generally expected that heavy fields are present during inflation, which can leave their imprint in late-time cosmological observables. The main signature of these fields is a small amount of distinctly shaped non-Gaussianity, which if detected, would provide a wealth of information about the particle spectrum of the inflationary Universe. Here we investigate to what extent these signatures can be detected or constrained using futuristic 21-cm surveys. We construct model-independent templates that extract the squeezed-limit behavior of the bispectrum, and examine their overlap with standard inflationary shapes and secondary non-Gaussianities. We then use these templates to forecast detection thresholds for different masses and couplings using a 3D reconstruction of modes during the dark ages (z ∼ 30 − 100). We consider interactions of several broad classes of models and quantify their detectability as a function of the baseline of a dark ages interferometer. Our analysis shows that there exists the tantalizing possibility of discovering new particles with different masses and interactions with future 21-cm surveys. Contents

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Cosmological Probes of Light Relics

Wallisch

2019

Springer Theses

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One of the primary targets of current and especially future cosmological observations are light thermal relics of the hot big bang. Within the Standard Model of particle physics, an important thermal relic are cosmic neutrinos, while many interesting extensions of the Standard Model predict new light particles which are even more weakly coupled to ordinary matter and therefore hard to detect in terrestrial experiments. On the other hand, these elusive particles may be produced efficiently in the early universe and their gravitational influence could be detectable in cosmological observables. In this thesis, we describe how measurements of the cosmic microwave background (CMB) and the large-scale structure (LSS) of the universe can shed new light on the properties of neutrinos and on the possible existence of other light relics.These cosmological observations are remarkably sensitive to the amount of radiation in the early universe, partly because free-streaming species such as neutrinos imprint a small phase shift in the baryon acoustic oscillations (BAO) which we study in detail in the CMB and LSS power spectra. Building on this analytic understanding, we provide further evidence for the cosmic neutrino background by independently confirming its free-streaming nature in different, currently available datasets. In particular, we propose and establish a new analysis of the BAO spectrum beyond its use as a standard ruler, resulting in the first measurement of this imprint of neutrinos in the clustering of galaxies.Future cosmological surveys, such as the next generation of CMB experiments (CMB-S4), have the potential to measure the energy density of relativistic species at the sub-percent level and will therefore be capable of probing physics beyond the Standard Model. We demonstrate how this improvement in sensitivity can indeed be achieved and present an observational target which would allow the detection of any extra light particle that has ever been in thermal equilibrium.Interestingly, even the absence of a detection would result in new insights by providing constraints on the couplings to the Standard Model. As an example, we show that existing bounds on additional scalar particles, such as axions, may be surpassed by orders of magnitude. For my parents DeclarationThis dissertation is the result of my own work and includes nothing which is the outcome of work done in collaboration except as declared below and specified in the text. Following the tendency of modern research in theoretical physics, most of the material discussed in this dissertation is the result of collaborative research. In particular, Chapters 4 and 6, and Appendices A, C and D are based on work done in collaboration with Daniel Baumann and Daniel Green, published in [1, 2], Chapter 5 and Appendix B are the result of the research done in collaboration with

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Non-Gaussianity as a particle detector

Cited by 229 publications

References 73 publications

Large gauge transformation, soft theorem, and Infrared divergence in inflationary spacetime

Large gauge transformation, soft theorem, and Infrared divergence in inflationary spacetime

Prospects for cosmological collider physics

Cosmological Probes of Light Relics

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