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This talk briefly explains how the breaking of a Lorentz-invariant description of nature at tiny space-time intervals might affect the non-Gaussian character of the primordial fluctuations left by inflation. For example, a model that…

High Energy Physics - Theory · Physics 2014-11-20 Hael Collins

Inflation produces super-horizon sized perturbations that ultimately return within the horizon and are thought to form the seeds of all observed large scale structure in the Universe. But inflationary predictions can only be compared with…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-03 Katherine Jones-Smith , Lawrence M. Krauss , Harsh Mathur

Assuming that primordial density fluctuationas are nearly Gaussian, from a frequentist viewpoint, the two-dimensional marginalized joint coincidence contour in the plane $(n_s,r)$ (being $n_s$ the spectral index and $r$ the ratio of tensor…

General Relativity and Quantum Cosmology · Physics 2016-12-21 Jaume de Haro

In [1], a most general higher curvature non-local gravity action was derived that admits a particular $R^2$-like inflationary solution predicting the spectral index of primordial scalar perturbations $n_s(N)\approx 1-\frac{2}{N}$, where $N$…

High Energy Physics - Theory · Physics 2023-07-18 Alexey S. Koshelev , K. Sravan Kumar , Alexei A. Starobinsky

The possibility that the non-minimal coupling inflation could be eternal is investigated. We calculate the quantum fluctuation of the inflaton in a Hubble time and find that it has the same value as in the minimal case in the slow-roll…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Chao-Jun Feng , Xin-Zhou Li

Current bounds from the polarization of the CMB predict the scale-invariant gravitational wave (GW) background of inflation to be out of reach for upcoming GW interferometers. This prospect dramatically changes if the inflaton is a…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-10 Valerie Domcke , Mauro Pieroni , Pierre Binétruy

According to the famous Lyth bound, one can confirm large field inflation by finding tensor modes with sufficiently large tensor-to-scalar ratio $r$. Here we will try to answer two related questions: Is it possible to rule out all large…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-08 Andrei Linde

In a situation like eternal inflation, where our data is replicated at infinitely-many other space-time events, it is necessary to make a prior assumption about our location to extract predictions. The principle of mediocrity entails that…

High Energy Physics - Theory · Physics 2022-05-25 Justin Khoury , Sam S. C. Wong

According to the `Cosmological Central Dogma', de Sitter space can be viewed as a quantum mechanical system with a finite number of degrees of freedom, set by the horizon area. We use this assumption together with the Wheeler-DeWitt (WDW)…

High Energy Physics - Theory · Physics 2025-12-01 Bjoern Hassfeld , Arthur Hebecker , Manfred Salmhofer , Jonah Cedric Strauss , Johannes Walcher

This is a review of models of inflation and of their predictions for the primordial non-Gaussianity in the density perturbations which are thought to be at the origin of structures in the Universe. Non-Gaussianity emerges as a key…

Astrophysics · Physics 2009-11-10 N. Bartolo , E. Komatsu , S. Matarrese , A. Riotto

We show that the prediction for the primordial tensor power spectrum cannot be modified at leading order in derivatives. Indeed, one can always set to unity the speed of propagation of gravitational waves during inflation by a suitable…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-10 Paolo Creminelli , Jérôme Gleyzes , Jorge Noreña , Filippo Vernizzi

There are two main approaches to non-equlibrium statistical mechanics: one using stochastic processes and the other using dynamical systems. To model the dynamics during inflation one usually adopts a stochastic description, which is known…

High Energy Physics - Theory · Physics 2016-03-29 Vitaly Vanchurin

We describe several different regimes which are possible in inflationary cosmology. The simplest one is inflation without self-reproduction of the universe. In this scenario the universe is not stationary. The second regime, which exists in…

High Energy Physics - Theory · Physics 2009-09-29 Juan Garcia-Bellido , Andrei Linde

We consider the non-commutative inflation model of [3] in which it is the unconventional dispersion relation for regular radiation which drives the accelerated expansion of space. In this model, we study the evolution of linear cosmological…

High Energy Physics - Theory · Physics 2008-11-26 Seoktae Koh , Robert H. Brandenberger

Inflationary cosmology provides a natural mechanism for the generation of primordial perturbations which seed the formation of observed cosmic structure and lead to specific signals of anisotropy in the cosmic microwave background…

Astrophysics · Physics 2011-07-19 Salman Habib , Andreas Heinen , Katrin Heitmann , Gerard Jungman

We address the problem of determining inflationary characteristics in a model independent way. We start from a recently proposed equation which allows to accurately calculate the value of the inflaton at horizon crossing $\phi_k$. We then…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-11 Gabriel German

We explore a broad class of three-parameter inflationary models, called the $\Lambda$-inflation, and its observational predictions: high abundance of cosmic gravitational waves consistent with the Harrison-Zel'dovich spectrum of primordial…

Astrophysics · Physics 2016-12-28 V. N. Lukash , E. V. Mikheeva

We attempt an estimate for the distribution of the tensor mode fraction $r$ over the landscape of vacua in string theory. The dynamics of eternal inflation and quantum tunneling lead to a kind of democracy on the landscape, providing no…

High Energy Physics - Theory · Physics 2015-06-05 Alexander Westphal

In this paper we consider the implications of the "landscape" paradigm for the large scale properties of the universe. The most direct implication of a rich landscape is that our local universe was born in a tunnelling event from a…

High Energy Physics - Theory · Physics 2009-11-11 Ben Freivogel , Matthew Kleban , Maria Rodriguez Martinez , Leonard Susskind

This is the third paper in a series establishing a quantitative relation between inflationary scalar field potential landscapes and the relic perturbations left by the collision between bubbles produced during eternal inflation. We…

High Energy Physics - Theory · Physics 2017-02-13 Matthew C. Johnson , Carroll L. Wainwright , Anthony Aguirre , Hiranya V. Peiris