scholarly journals ASPECTS OF WARM-FLAT DIRECTIONS

2010 ◽  
Vol 25 (22) ◽  
pp. 4221-4237 ◽  
Author(s):  
TOMOHIRO MATSUDA
Keyword(s):  
Thermal Equilibrium ◽  
Strong Interactions ◽  
Cosmological Perturbations ◽  
Inflaton Field ◽  
Warm Inflation ◽  
Qualitative And Quantitative ◽  
Slow Roll ◽  
Dissipative Coefficient ◽  
Inflation Scenario

Considering the mechanism of dissipative slow-roll that has been used in warm inflation scenario, we show that dissipation may alter usual cosmological scenarios associated with SUSY-flat directions. We mainly consider SUSY-flat directions that have strong interactions with nonflat directions and may cause strong dissipation both in thermal and nonthermal backgrounds. An example is the Affleck–Dine mechanism in which dissipation may create significant (both qualitative and quantitative) discrepancies between the conventional scenario and the dissipative one. We also discuss several mechanisms of generating curvature perturbations in which the dissipative field, which is distinguished from the inflaton field, can be used as the source of cosmological perturbations. Considering the Morikawa–Sasaki dissipative coefficient, the damping caused by the dissipation may be significant for many MSSM flat directions even if the dissipation is far from thermal equilibrium.

scholarly journals Pre-inflation dynamical behavior of warm inflation in loop quantum cosmology

2020 ◽  
Vol 35 (35) ◽  
pp. 2050293
Author(s):  
Kui Xiao ◽  
Sheng-Qin Wang
Keyword(s):  
Quantum Cosmology ◽  
Initial Conditions ◽  
Dynamical Behavior ◽  
Loop Quantum Cosmology ◽  
Warm Inflation ◽  
Dynamical Behaviors ◽  
Slow Roll ◽  
Dissipative Coefficient ◽  
Slow Roll Inflation ◽  
Three Phases

Considering a constant dissipative coefficient [Formula: see text], the pre-inflation dynamical behaviors of warm inflation in the loop quantum cosmology scenario are discussed. We consider three sets of initial conditions. The evolution of the background can always be divided into three phases, namely super-inflation, damping, and slow-roll inflation phases, with the duration of each phase depending on the initial conditions. As an example, we compare the background evolution between [Formula: see text] and [Formula: see text] under special initial conditions and find that there is no slow-roll inflation phase for [Formula: see text] while the number of e-folds is about 60.209 for [Formula: see text].

Warm logamediate inflation in Starobinsky inflationary model

2018 ◽  
Vol 27 (02) ◽  
pp. 1750191
Author(s):  
M. Sharif ◽  
Iqra Nawazish
Keyword(s):  
Scalar Potential ◽  
Power Spectra ◽  
Graphical Analysis ◽  
Strong Interactions ◽  
Inflationary Model ◽  
Tensor Power ◽  
Warm Inflation ◽  
Dissipative Effects ◽  
Dissipative Coefficient ◽  
Weak Regime

This paper investigates the dynamics of warm logamediate inflation for flat isotropic and homogeneous universe in Einstein frame representation of [Formula: see text] gravity. In this scenario, we study dissipative effects for weak and strong interactions of inflaton field via constant and generalized dissipative coefficient. In both interacting regimes, we find inflaton solution corresponding to scalar potential and radiation density of dissipating inflaton. Under slow-roll approximation, we formulate scalar and tensor power spectra, their spectral indices and tensor–scalar ratio for Starobinsky inflationary model and construct graphical analysis of these observational parameters. It is concluded that this model remains compatible with Planck 2015 constraints in weak and strong regimes for constant dissipative coefficient. For generalized dissipative coefficient, the inflationary model yields consistent results for [Formula: see text] and [Formula: see text] in strong regime while condition of warm inflation is violated for [Formula: see text] in weak regime.

Experiments on strong interactions between solitary waves

1978 ◽  
Vol 85 (3) ◽  
pp. 417-431 ◽  
Author(s):  
P. D. Weidman ◽  
T. Maxworthy
Keyword(s):  
Shallow Water ◽  
Solitary Waves ◽  
Water Waves ◽  
Vries Equation ◽  
Rectangular Channel ◽  
Quantitative Agreement ◽  
Strong Interactions ◽  
Shallow Water Waves ◽  
Qualitative And Quantitative ◽  
The Waves

Experiments on the interaction between solitary shallow-water waves propagating in the same direction have been performed in a rectangular channel. Two methods were devised to compensate for the dissipation of the waves in order to compare results with Hirota's (1971) solution for the collision of solitons described by the Kortewegde Vries equation. Both qualitative and quantitative agreement with theory is obtained using the proposed corrections for wave damping.

scholarly journals Generalized Galileon scenario inspires chaotic inflation

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Matías López ◽  
Jorge Maggiolo ◽  
Nelson Videla ◽  
Pablo González ◽  
Grigoris Panotopoulos
Keyword(s):  
General Relativity ◽  
Observational Data ◽  
Kinetic Term ◽  
Cosmological Perturbations ◽  
Slow Roll ◽  
Field Oscillation ◽  
General Conditions ◽  
Chaotic Inflation

Abstract We study chaotic inflation with a Galileon-like self-interaction $$G(\phi ,X)\Box \phi $$G(ϕ,X)□ϕ, where $$G(\phi ,X)\propto X^{n}$$G(ϕ,X)∝Xn. General conditions required for successful inflation are deduced and discussed from the background and cosmological perturbations under slow-roll approximation. Interestingly, it is found that in the regime where the Galileon term dominates over the standard kinetic term, the tensor-to-scalar ratio becomes significantly suppressed in comparison to the standard expression in General Relativity (GR). Particularly, we find the allowed range in the space of parameters characterizing the chaotic quadratic and quartic inflation models by considering the current observational data of Planck from the $$n_{\mathcal {S}}-r$$nS-r plane. Finally, we discuss about the issue if the Galileon term is dominant by the end of inflation, this can affect the field oscillation during reheating.

ON THE STOCHASTIC EVOLUTION OF THE INFLATON FIELD

2004 ◽  
Vol 13 (07) ◽  
pp. 1315-1320 ◽  
Author(s):  
JOÃO MARIA SILVA ◽  
JOSÉ A. S. LIMA
Keyword(s):  
Thermal Contact ◽  
Initial Density ◽  
Type Equation ◽  
Thermal Bath ◽  
Large Set ◽  
Stochastic Evolution ◽  
Thermally Induced ◽  
Inflaton Field ◽  
Warm Inflation ◽  
Density Perturbations

During the inflationary regime, the expansion of the Universe is driven by a scalar field ϕ(t) which may be in thermal contact with the radiation fluid. In this work, we study the influence of the thermal bath assuming that it is responsible for the stochastic evolution of the inflaton field. Assuming that the fluctuation dynamics is described by a Langevin-type equation of motion, a large set of analytical solutions including white and colored noises are derived. It is found that even in the case of white noise the field experience an anomalous diffusion. Such results may be important for studying thermally induced initial density perturbations in inflationary cosmologies, mainly in the framework of warm inflation.

scholarly journals Asymptotic Solutions of a Generalized Starobinski Model: Kinetic Dominance, Slow Roll and Separatrices

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 500
Author(s):  
Elena Medina ◽  
Luis Martínez Alonso
Keyword(s):  
Asymptotic Expansions ◽  
Hubble Parameter ◽  
Initial Conditions ◽  
Asymptotic Solutions ◽  
Inflationary Model ◽  
Series Solutions ◽  
Fixed Amount ◽  
Inflaton Field ◽  
Slow Roll ◽  
Jacobi Formalism

We consider a generalized Starobinski inflationary model. We present a method for computing solutions as generalized asymptotic expansions, both in the kinetic dominance stage (psi series solutions) and in the slow roll stage (asymptotic expansions of the separatrix solutions). These asymptotic expansions are derived in the framework of the Hamilton-Jacobi formalism where the Hubble parameter is written as a function of the inflaton field. They are applied to determine the values of the inflaton field when the inflation period starts and ends as well as to estimate the corresponding amount of inflation. As a consequence, they can be used to select the appropriate initial conditions for determining a solution with a previously fixed amount of inflation.

Reconstruction of warm Chaplygin gas inflationary models

2020 ◽  
Vol 35 (32) ◽  
pp. 2050268
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
Kazuharu Bamba ◽  
Nadeem Azhar
Keyword(s):  
Spectral Index ◽  
Effective Potential ◽  
Chaplygin Gas ◽  
Index Formula ◽  
Curvature Perturbation ◽  
Warm Inflation ◽  
Scalar Spectral Index ◽  
Dissipative Coefficient ◽  
Inflationary Parameters ◽  
Friedmann Robertson Walker

By assuming the specific Chaplygin gas model, we study the reconstruction of warm inflation model with the help of tensor-to-scalar ratio [Formula: see text] and scalar spectral index [Formula: see text]. In this regard, we take flat Friedmann–Robertson–Walker (FRW) metric and discuss the general forms of dissipative coefficient [Formula: see text] as well as effective potential [Formula: see text] for two dissipative regimes i.e., the weak and strong. We use inflationary parameters such as slow-roll parameters, power spectrum of the curvature perturbation, tensor spectrum, spectral index, scalar-to-tensor ratio and Hubble parameter to find the generalized form of dissipative coefficient and effective potential. We discuss the results of dissipative coefficient and reconstructed potential in detail for the specific choice of tensor-to-scalar ratio [Formula: see text] and scalar spectral index [Formula: see text].

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