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We study the effects of non-trivial initial quantum states for inflationary fluctuations within the context of the effective field theory for inflation constructed by Cheung et al. which allows us to discriminate between different initial…

High Energy Physics - Theory · Physics 2013-11-20 Nishant Agarwal , R. Holman , Andrew J. Tolley , Jennifer Lin

We study the equivalence of two - order-by-order Einstein's equation and Reduced action - approaches to cosmological perturbation theory at all orders for different models of inflation. We point out a crucial consistency check which we…

General Relativity and Quantum Cosmology · Physics 2016-06-21 Debottam Nandi , S. Shankaranarayanan

We present a simple effective field theory formulation of a general family of single field flux monodromy models for which strong coupling effects at large field values can flatten the potential and activate operators with higher powers of…

High Energy Physics - Theory · Physics 2018-09-12 Guido D'Amico , Nemanja Kaloper , Albion Lawrence

In this paper we provide a consistency relation between the amplitude of the hemispherical bipolar asymmetry, $A$, and the amplitude of the primordial non-Gaussianity in the squeezed limit, $f_{NL}$, as $|A| \lesssim 10^{-1} f_{NL}$. We…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-30 Mohammad Hossein Namjoo , Shant Baghram , Hassan Firouzjahi

We investigate a single field model in the context of the constant-roll inflation in which inflaton moves down to the minimum point of the potential with a constant rate of rolling. We use a quintessential inflationary model obtained by a…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-23 Mehdi Shokri , Jafar Sadeghi , Saeed Noori Gashti

We derive consistency relations for correlators of scalar cosmological perturbations which hold in the "squeezed limit" in which one or more of the external momenta become soft. Our results are formulated as relations between suitably…

High Energy Physics - Theory · Physics 2013-06-14 Walter D. Goldberger , Lam Hui , Alberto Nicolis

We investigate multi-field inflationary scenarios with fields that drop out of the model in a staggered fashion. This feature is natural in certain multi-field inflationary setups within string theory; for instance, it can manifest itself…

High Energy Physics - Theory · Physics 2009-12-10 Diana Battefeld , Thorsten Battefeld , Anne-Christine Davis

It is well known that the non-Gaussianity parameter $f_{_{\rm NL}}$ characterizing the scalar bi-spectrum can be expressed in terms of the scalar spectral index in the squeezed limit, a property that is referred to as the consistency…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 V. Sreenath , L. Sriramkumar

Combining the stochastic and $\delta N$ formalisms, we derive non perturbative analytical expressions for all correlation functions of scalar perturbations in single-field, slow-roll inflation. The standard, classical formulas are recovered…

High Energy Physics - Theory · Physics 2016-12-01 Vincent Vennin , Alexei A. Starobinsky

Inflationary consistency equations relate the scalar and tensor perturbations. We elucidate the infinite hierarchy of consistency equations of single-field inflation, the first of which is the well-known relation A_T^2/A_S^2 = -n_T/2…

Astrophysics · Physics 2009-11-11 Marina Cortês , Andrew R Liddle

We revisit perturbative unitarity in scalar field inflation with a nonminimal coupling, with Higgs inflation serving as the most prominent example. Although such models are phenomenologically successful, it is critical to examine whether or…

High Energy Physics - Phenomenology · Physics 2025-05-28 Thomas Steingasser , Mark P. Hertzberg , David I. Kaiser

We study the consequences of spatial coordinate transformation in multi-field inflation. Among the spontaneously broken de Sitter isometries, only dilatation in the comoving gauge preserves the form of the metric and thus results in…

High Energy Physics - Theory · Physics 2018-02-21 Jinn-Ouk Gong , Min-Seok Seo

Single scalar field inflation with a generic, non-quadratic in derivatives, field Lagrangian is considered. It is shown that non-Gaussianity of curvature perturbations is characterized by two dimensionless amplitudes. One of these…

Astrophysics · Physics 2009-11-10 Andrei Gruzinov

We construct a model of inflation in string theory after carefully taking into account moduli stabilization. The setting is a warped compactification of Type IIB string theory in the presence of D3 and anti-D3-branes. The inflaton is the…

High Energy Physics - Theory · Physics 2014-11-18 Norihiro Iizuka , Sandip P. Trivedi

We study the stability of an inflaton condensate in the presence of attractive inflaton self-interactions, in order to determine analytical conditions on the self-interaction couplings under which the condensate undergoes fragmentation. As…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-28 Jinsu Kim , John McDonald

We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that…

General Relativity and Quantum Cosmology · Physics 2017-02-01 Martin G. Richarte , Gilberto M. Kremer

We show that inflation can naturally occur at a finite temperature T>H that is sustained by dissipative effects, when the inflaton field corresponds to a pseudo Nambu-Goldstone boson of a broken gauge symmetry. Similarly to "Little Higgs"…

High Energy Physics - Phenomenology · Physics 2016-10-12 Mar Bastero-Gil , Arjun Berera , Rudnei O. Ramos , Joao G. Rosa

Dissipative effects can lead to a friction term in the equation of motion for an inflaton field during the inflationary era. The friction term may be linear and localised, in which case it is described by a dissipation coefficient. The…

High Energy Physics - Phenomenology · Physics 2007-05-23 Ian G Moss , Chun Xiong

In this paper, we study a constant-roll inflationary model in the presence of a noncommutative parameter with a homogeneous scalar field minimally coupled to gravity. The specific noncommutative inflation conditions proposed new…

High Energy Physics - Theory · Physics 2023-02-14 J. Sadeghi , S. Noori Gashti

We explore the inflationary phase of a scalar field with a kinetic term non-minimally coupled to gravity. We find that one of the slow-roll conditions is naturally consequence of the equation of motion of the scalar field. Thus, slow-roll…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-16 Amir Ghalee