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Related papers: Anisotropic Inflation with the non-Vacuum Initial …

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The behaviour of a non-canonical scalar field within an anisotropic Bianchi type I, spatially homogeneous, Universe in the framework of the intermediate inflation will be studied. It will be examined on the condition that both the…

General Physics · Physics 2019-08-19 Mahdeyeh Naderi , Ali Aghamohammadi , Abdollah Refaei , Haidar Sheikhahmadi

It is usually assumed that the inflationary fluctuations start from the Bunch-Davies (BD) vacuum and the $i\varepsilon$ prescription is used when interactions are calculated. We show that those assumptions can be verified explicitly by…

High Energy Physics - Theory · Physics 2016-04-27 Hongliang Jiang , Yi Wang , Siyi Zhou

We explore extensions of hybrid inflationary models in the context of supersymmetric D-term inflation. We point out that a large variety of inflationary scenarios can be encountered when the field content is extended. It is not only…

High Energy Physics - Phenomenology · Physics 2008-11-26 Francis Bernardeau , Tristan Brunier

In axion gauge field inflation an axion-like particle driving cosmic inflation is coupled to the Chern-Simons density of an Abelian or non-Abelian gauge group. In the case of a non-Abelian gauge group, this can lead to the formation of a…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-24 Valerie Domcke , Stefan Sandner

The Bunch-Davies state appears precisely thermal to a free-falling observer in de Sitter space. However, precise thermality is unphysical because it violates energy conservation. Instead, the true spectrum must take a certain different…

High Energy Physics - Theory · Physics 2009-11-11 Brian Greene , Maulik Parikh , Jan Pieter van der Schaar

Recent observations opened up a new window on the inflationary model building. As it was firstly reported by the WMAP data, there may be some indications of statistical anisotropy on the CMB map, although the statistical significance of…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-06 Razieh Emami

We investigate the $\phi^2$ inflationary model in the Bianchi-I spacetime using effective spacetime description of loop quantum cosmology to understand the issues of the resolution of initial singularity, isotropization, effect of…

General Relativity and Quantum Cosmology · Physics 2013-07-11 Brajesh Gupt , Parampreet Singh

We present a new mechanism for generating primordial statistical anisotropy of curvature perturbations. We introduce a vector field which has a non-minimal kinetic term and couples with a waterfall field in hybrid inflation model. In such a…

Astrophysics · Physics 2011-07-13 Shuichiro Yokoyama , Jiro Soda

In the context of inflation, non-vacuum initial states for cosmological perturbations that possess a built in scale are studied. It is demonstrated that this assumption leads to a falsifiable class of models. The question of whether they…

Astrophysics · Physics 2009-10-31 Jerome Martin , Alain Riazuelo , Mairi Sakellariadou

The effect of the initial condition of inflation on the power spectra of scalar and tensor perturbations is estimated assuming a slow-roll inflation model. By defining a more general initial state in inflation particular properties of the…

Astrophysics · Physics 2007-10-15 Shiro Hirai , Tomoyuki Takami

It is known that stochastic gravitational wave backgrounds (SGWBs) have anisotropies generated by squeezed-type tensor non-Gaussianities originating from scalar-tensor-tensor (STT) and tensor-tensor-tensor cubic interactions. While the…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-01 Shingo Akama , Shin'ichi Hirano , Shuichiro Yokoyama

We study an anisotropic inflation model with a gauge kinetic function for a non-abelian gauge field. We find that, in contrast to abelian models, the anisotropy can be either a prolate or an oblate type, which could lead to a different…

High Energy Physics - Theory · Physics 2015-05-27 Keiju Murata , Jiro Soda

Cosmological inflation remains to be a unique mechanism of generation of plausible initial conditions in the early universe. In particular, it generates the primordial quasiclassical perturbations with power spectrum determined by the…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-23 Yuri Shtanov

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 study an inflationary scenario with a two-form field to which an inflaton couples non-trivially. First, we show that anisotropic inflation can be realized as an attractor solution and that the two-form hair remains during inflation. A…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-16 Junko Ohashi , Jiro Soda , Shinji Tsujikawa

We consider models of inflation with U(1) gauge fields and charged scalar fields including symmetry breaking potential, chaotic inflation and hybrid inflation. We show that there exist attractor solutions where the anisotropies produced…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-18 Razieh Emami , Hassan Firouzjahi , S. M. Sadegh Movahed , Moslem Zarei

The influence of Inflation on initial (i.e. at Planck's epoch) large anisotropy of the Universe is studied, considering a more general metric than the isotropic one: the locally rotationally symmetric (L.R.S.) Bianchi IX metric. We find,…

General Relativity and Quantum Cosmology · Physics 2014-11-17 R. Bergamini , P. Sedici , P. Verrocchio

Non-abelian gauge field inflation is studied in the context of warm inflation scenario. We introduce this scenario as a mechanism that gives an end for gauge-flation model. Slow-roll parameters and perturbation parameters are presented for…

General Relativity and Quantum Cosmology · Physics 2015-06-17 M. R. Setare , V. Kamali

We investigate the dynamics of homogeneous phase space for single-field models of inflation. Inflationary trajectories are formally attractors in phase space, but since in practice not all initial conditions lead to them, some degree of…

High Energy Physics - Theory · Physics 2014-11-20 Paul Franche , Rhiannon Gwyn , Bret Underwood , Alisha Wissanji

Dynamics of the inflaton is studied when it interacts with boson and fermion fields and in minimal supersymmetric models. This encompasses multifield inflation models, such as hybrid inflation, and typical reheating models. For much of the…

High Energy Physics - Phenomenology · Physics 2009-11-10 Arjun Berera , Rudnei O. Ramos