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We study the non-Gaussianity in the simplest infrared (IR) model of the DBI inflation. We show that the non-Gaussianity in such a model is compatible with the current observational bound, and is within the sensitivity of future experiments.…

Astrophysics · Physics 2009-11-13 Xingang Chen

In this paper we calculate additional contributions to that part of the non-Gaussianity of the curvature perturbation, which come from the three-point correlator of the field perturbations. We estimate this contribution in the following…

Astrophysics · Physics 2007-05-23 Ignacio Zaballa , Yeinzon Rodriguez , David H. Lyth

We perform a general study of the primordial scalar non-Gaussianities in multi-field inflationary models in Einstein gravity. We consider models governed by a Lagrangian which is a general function of the scalar fields and their first…

Astrophysics · Physics 2009-06-23 Xian Gao

These notes present a detailed introduction to Maldacena's calculation of the three-point function generated by the simplest class of inflationary models: those with a single inflaton field whose potential satisfies the slow-roll conditions…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-02 Hael Collins

We compute the three-point correlation function of primordial scalar density perturbations in a general single-field inflationary scenario, where a scalar field phi has a direct coupling with the Ricci scalar R and the Gauss-Bonnet term GB.…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-22 Antonio De Felice , Shinji Tsujikawa

In this review, we discuss how non-Gaussianity of cosmological perturbations arises from inflation. After introducing the in-in formalism to calculate the $n$-point correlation function of quantum fields, we present the computation of the…

High Energy Physics - Theory · Physics 2014-11-20 Kazuya Koyama

We study the non-gaussianity from the bispectrum in multi-field inflation models with a general kinetic term. The models include the multi-field K-inflation and the multi-field Dirac-Born-Infeld (DBI) inflation as special cases. We find…

High Energy Physics - Theory · Physics 2011-02-07 Frederico Arroja , Shuntaro Mizuno , Kazuya Koyama

We calculate the primordial correlation of gravitons with an abelian gauge field non-minimally coupled through a dynamical dilaton field or a volume moduli during inflation in the early universe. In particular, we compute the…

High Energy Physics - Theory · Physics 2022-03-25 Rajeev Kumar Jain , P. Jishnu Sai , Martin S. Sloth

We explore possible non-Gaussian features of primordial gravitational waves by constructing model-independent templates for nonlinearity parameters of tensor bispectrum. Our analysis is based on Effective Field Theory of inflation that…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-16 Abhishek Naskar , Supratik Pal

We study the inflation in a model with a Gauss-Bonnet term which is non-minimally coupled to a DBI field. We study the spectrum of the primordial perturbations in detail. The non-Gaussianity of this model is considered and the amplitude of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Kourosh Nozari , Narges Rashidi

We study non-Gaussian signatures on the cosmic microwave background (CMB) radiation predicted within inflationary models with non-vacuum initial states for cosmological perturbations. The model incorporates a privileged scale, which implies…

Astrophysics · Physics 2008-11-26 Alejandro Gangui , Jerome Martin , Mairi Sakellariadou

We study a model of multiple-field DBI inflation leading to mixed form of primordial non-Gaussianity, including equilateral and local bispectrum shapes. We present a general formalism based on the Hamilton-Jacobi approach, allowing us to go…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-23 Jon Emery , Gianmassimo Tasinato , David Wands

We study the consequences of imposing an approximate Galilean symmetry on the Effective Theory of Inflation, the theory of small perturbations around the inflationary background. This approach allows us to study the effect of operators with…

High Energy Physics - Theory · Physics 2015-03-17 Paolo Creminelli , Guido D'Amico , Marcello Musso , Jorge Noreña , Enrico Trincherini

We analyze the non--Gaussian primordial fluctuations which are inescapably contributed by scalar fields $\Phi$ with vanishing expectation values, $\langle\Phi\rangle=0$, present during inflation in addition to the inflaton field. For…

General Relativity and Quantum Cosmology · Physics 2009-09-25 Harald F. Muller , Christoph Schmid

It has been found that the primordial non-Gaussianity of the curvature perturbation in the case of non-Bunch-Davies initial states can be enhanced compared with those in the case of the Bunch-Davies one due to the interactions among the…

General Relativity and Quantum Cosmology · Physics 2020-07-15 Shingo Akama , Shin'ichi Hirano , Tsutomu Kobayashi

We calculate the three-point function for primordial scalar fluctuations in a single field inflationary scenario where the scalar field Lagrangian is a completely general function of the field and its first derivative. We obtain an explicit…

Astrophysics · Physics 2009-07-09 David Seery , James E. Lidsey

This is a pedagogical review on primordial non-Gaussianities from inflation models. We introduce formalisms and techniques that are used to compute such quantities. We review different mechanisms which can generate observable large…

Cosmology and Nongalactic Astrophysics · Physics 2010-09-10 Xingang Chen

The late-time effect of primordial non-Gaussianity offers a window into the physics of inflation and the very early Universe. In this work we study the consequences of a particular class of primordial non-Gaussianity that is fully…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-09 G. A. Peña , G. N. Candlish

We analyze primordial non-gaussianities in presence of an ultra-slow phase during the inflationary dynamics, focusing on scenarios relevant for the production of primordial black holes. We compute the three-point correlation function of…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-25 Marco Taoso , Alfredo Urbano

In this work, we present a method for implementing the $\delta N$ formalism to study the primordial non-Gaussianity produced in multiple three-form field inflation. Using a dual description relating three-form fields to noncanonical scalar…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-09 K. Sravan Kumar , David J. Mulryne , Nelson J. Nunes , João Marto , Paulo Vargas Moniz