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Thermal inflation models (which feature two inflationary stages) can display damped primordial curvature power spectra on small scales which generate damped matter fluctuations. For a reasonable choice of parameters, thermal inflation…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-11 Matteo Leo , Carlton M. Baugh , Baojiu Li , Silvia Pascoli

Picking out DBI scalar field as inflation, the slow-rolling inflationary scenario is studied by attributing an exponential time function to scale factor; known as intermediate inflation. The perturbation parameters of the model are…

General Relativity and Quantum Cosmology · Physics 2017-08-15 N. Nazavari , A. Mohammadi , Z. Ossoulian , Kh. Saaidi

A model is developed in which the inflaton potential experiences a sudden small change in its second derivative (the effective mass of the inflaton). An exact treatment demonstrates that the resulting density perturbation has a quasi-flat…

Astrophysics · Physics 2008-12-18 Minu Joy , Varun Sahni , Alexei A. Starobinsky

The purpose of these lectures is to give a pedagogical introduction to inflation and the production of primordial perturbations, as well as a review of some of the latest developments in this domain. After a short introduction, we review…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 David Langlois

In this letter, we propose a model of inflationary cosmology with a bounce preceded and study its primordial curvature perturbations. Our model gives rise to a primordial power spectrum with a feature of oscillation on large scales compared…

Astrophysics · Physics 2009-02-02 Yi-Fu Cai , Tao-tao Qiu , Jun-Qing Xia , Xinmin Zhang

Massive spinning particles, if present during inflation, lead to a distinctive bispectrum of primordial perturbations, the shape and amplitude of which depend on the masses and spins of the extra particles. This signal, in turn, leaves an…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-16 Azadeh Moradinezhad Dizgah , Hayden Lee , Julian B. Muñoz , Cora Dvorkin

The phase-integral approximation devised by Fr\"oman and Fr\"oman, is used for computing cosmological perturbations in the power-law inflationary model. The phase-integral formulas for the scalar and tensor power spectra are explicitly…

Astrophysics · Physics 2008-11-26 Clara Rojas , Victor M. Villalba

Inflationary models predicting a scale-dependent large amplification of the density perturbations have recently attracted a lot of attention because the amplified perturbations can seed a sizable amount of primordial black holes (PBHs) and…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-28 Keisuke Inomata , Matteo Braglia , Xingang Chen , Sébastien Renaux-Petel

We revisit an extension of the well-known formalism for gauge-invariant scalar metric fluctuations, to study the spectrums for both, the inflaton and gauge invariant (scalar) metric fluctuations in the framework of a single field…

General Relativity and Quantum Cosmology · Physics 2009-11-13 Mariano Anabitarte , Mauricio Bellini

A self-consistent modular cosmology scenario and its testability in view of future CMB experiments are discussed. Particular attention is drawn to the enhanced symmetric points in moduli space which play crucial roles in our scenario. The…

High Energy Physics - Phenomenology · Physics 2015-06-25 Kenji Kadota , Ewan D. Stewart

Non-Gaussianity in the distribution of inflationary perturbations, measurable in statistics of the cosmic microwave background (CMB) and large scale structure fluctuations, can be used to probe non-trivial initial quantum states for these…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Joyce Byun , Nishant Agarwal , Rachel Bean , Richard Holman

The most popular tools for analysing the large scale distribution of galaxies are second-order spatial statistics such as the two-point correlation function or its Fourier transform, the power spectrum. In this review, we explain how our…

Astrophysics · Physics 2015-05-13 Vicent J. Martinez

We develop a general formalism for analyzing linear perturbations in multiple-field cosmological inflation based on the gauge-ready approach. Our inflationary model consists of an arbitrary number of scalar fields with non-minimal kinetic…

Astrophysics · Physics 2009-11-13 Joydev Lahiri , Gautam Bhattacharya

We investigate how various inflationary and bouncing cosmologies can be realized by imperfect fluids with a generalized equation of state, in the context of both classical and loop quantum cosmology. With regards to the inflationary…

General Relativity and Quantum Cosmology · Physics 2017-09-06 V. K. Oikonomou

We investigate scalar perturbations from inflation in a bulk inflaton braneworld model. Using the generalized longitudinal gauge, we derive and solve the full set of scalar perturbation equations. Our exact results support the recent…

High Energy Physics - Theory · Physics 2009-11-10 Da-Ping Du , Bin Wang , Elcio Abdalla , Ru-Keng Su

We examine Gaussian isocurvature hot dark matter (massive neutrino) models for large-scale structure in which the initial density perturbations are produced in the baryons with a power--law spectrum $P_B(k) = Ak^{n_B}$. We calculate the…

Astrophysics · Physics 2009-10-28 Andrew A. de Laix , Rober J. Scherrer

In standard inflationary cosmology, scalar and tensor perturbations grew as the Universe expanded and froze when their wavelengths exceeded the Hubble horizon, producing a tell-tale signature in the fluctuation spectrum and amplitude of the…

General Relativity and Quantum Cosmology · Physics 2023-07-21 Fulvio Melia

The discovery of gravitational waves from merging binary black holes has generated considerable interest in examining whether these black holes could have a primordial origin. If a significant number of black holes have to be produced in…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-07 H. V. Ragavendra , L. Sriramkumar

We study the warm-tachyon inflationary universe model with viscous pressure in high-dissipation regime. General conditions which are required for this model to be realizable are derived in the slow-roll approximation. We present analytic…

General Relativity and Quantum Cosmology · Physics 2015-06-22 M. R. Setare , V. Kamali

The non-Gaussianity of inflationary perturbations, as encoded in the bispectrum (or 3-point correlator), has become an important additional way of distinguishing between inflation models, going beyond the linear Gaussian perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-23 Bartjan van Tent