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By studying the chameleon model during inflation, we investigate whether it can be a successful inflationary model, wherein we employ the common typical potential usually used in the literature. Thus, in the context of the slow-roll…

General Relativity and Quantum Cosmology · Physics 2018-04-13 Nasim Saba , Mehrdad Farhoudi

In double-field inflation, which exploits two scalar fields, one of the fields rolls slowly during inflation whereas the other field is trapped in a meta-stable vacuum. The nucleation rate from the false vacuum to the true one becomes…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Amjad Ashoorioon

In the phase space perspective, scalar field slow roll inflation is described by a heteroclinic orbit from a saddle type fixed point to a final attractive point. In many models the saddle point resides in the scalar field asymptotics, and…

General Relativity and Quantum Cosmology · Physics 2025-10-29 Laur Järv , Dmitri Kraiko

Quantum fast-roll initial conditions for the inflaton which are different from the classical fast-roll conditions and from the quantum slow-roll conditions can lead to inflation that last long enough. These quantum fast-roll initial…

Astrophysics · Physics 2009-01-01 F. J. Cao , H. J. de Vega , N. G. Sanchez

We investigate all single-field, slow-roll inflationary models whose slow-roll parameters scale as 1/N in the limit of a large number of e-folds N. We proof that all such models belong to two universality classes, characterised by a single…

High Energy Physics - Theory · Physics 2015-06-17 Diederik Roest

In this work, we investigate how a smooth transition from a constant-roll to a slow-roll inflationary era may be realized, in the context of a canonical scalar field theory. We study in some detail the dynamical evolution of the…

General Relativity and Quantum Cosmology · Physics 2018-02-14 V. K. Oikonomou

In this paper we analyze scalar gravitational perturbations on a Robertson-Walker background in the presence of multiple scalar fields that take values on a (geometrically non-trivial) field manifold during slow-roll inflation. For this…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. Groot Nibbelink , B. J. W. van Tent

The space of parameters characterizing an inflationary primordial power spectrum with small superimposed oscillations is explored using Monte Carlo methods. The most interesting region corresponding to high frequency oscillations is…

High Energy Physics - Phenomenology · Physics 2009-11-10 Jerome Martin , Christophe Ringeval

We present constraints on how far single field inflation may depart from the familiar slow-roll paradigm. Considering a fast-roll regime while requiring a (near)-scale-invariant power spectrum introduces large self-interactions for the…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-12 Johannes Noller

Through a principal component analysis, we study how accurately CMB observables can constrain inflaton potentials in a model independent manner. We apply the general slow-roll approximation in our analysis where we allow, in contrast to the…

Astrophysics · Physics 2008-11-26 Kenji Kadota , Scott Dodelson , Wayne Hu , Ewan D. Stewart

We define a new inflationary scenario in which inflation starts naturally after the Big Bang when the energy density drops below some critical value. As a model, we use recently proposed symmetron field whose effective potential depends on…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-02 Ruifeng Dong , William H. Kinney , Dejan Stojkovic

In this paper we illustrate an interesting example of low scale inflation with an extremely large number of e-foldings. This realization can be implemented easily in hybrid inflation model where usually inflation ends via phase transition.…

High Energy Physics - Theory · Physics 2007-05-23 Anupam Mazumdar

Slow-roll inflation is studied as an effective field theory.We find as consistent form of the inflaton potential V(phi)=N M^4 w(phi/[sqrt{N}M_P]) where phi is the inflaton field, M the inflation energy scale, M_P the Planck mass, and N~50…

Astrophysics · Physics 2009-11-13 D. Boyanovsky , H. J. de Vega , N. G. Sanchez

Departing from standard slow-roll conditions is one way of putting the inflationary paradigm to test, and constraining the dynamics of the inflaton field with a constant-rate of roll of the inflaton field, a.k.a. the constant-roll scenario,…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-19 Sandip Biswas , Kaushik Bhattacharya , Suratna Das

We compute the 3-point correlation function for a general model of inflation driven by a single, minimally coupled scalar field. Our approach is based on the numerical evaluation of both the perturbation equations and the integrals which…

Astrophysics · Physics 2010-10-27 Xingang Chen , Richard Easther , Eugene A. Lim

In light of the most recent cosmological observations, we provide new updated constraints on the slow-roll inflation in different extended scenarios beyond the $\Lambda\rm{CDM}$ cosmological model. Along with the usual six parameters, we…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-25 Matteo Forconi , William Giarè , Eleonora Di Valentino , Alessandro Melchiorri

We revisit the one-loop corrections on CMB scale perturbations induced from small scale modes in single field models which undergo a phase of ultra slow-roll inflation. There were concerns that large loop corrections are against the notion…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-08 Hassan Firouzjahi

In addition to generating the appropriate perturbation power spectrum, an inflationary scenario must take into account the need for inflation to end subsequently. In the context of single-field inflation models where inflation ends by…

Astrophysics · Physics 2009-11-10 Michaël Malquarti , Samuel M. Leach , Andrew R. Liddle

The recent BICEP2 detection of degree scale CMB B-mode polarization, coupled with a deficit of observed power in large angle temperature anisotropy, suggest that the slow-roll parameter $\epsilon_H$, the fractional variation in the Hubble…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-11 Wayne Hu

We study the seemingly duality between large and small $\eta_H$ for the constant-roll inflation with the second slow-roll parameter $\eta_H$ being a constant. In the previous studies, only the constant-roll inflationary models with small…

General Relativity and Quantum Cosmology · Physics 2019-11-01 Qing Gao , Yungui Gong , Zhu Yi
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