scholarly journals Implications of a running spectral index for slow roll inflation

2006 ◽  
Vol 2006 (09) ◽  
pp. 010-010 ◽  
Author(s):  
Richard Easther ◽  
Hiranya V Peiris
Keyword(s):  
Spectral Index ◽  
Slow Roll ◽  
Slow Roll Inflation

scholarly journals General Slow-Roll Inflation in f(R) Gravity under the Palatini Approach

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1958
Author(s):  
Sabit Bekov ◽  
Kairat Myrzakulov ◽  
Ratbay Myrzakulov ◽  
Diego Sáez-Chillón Gómez
Keyword(s):  
Scalar Field ◽  
Simple Model ◽  
Spectral Index ◽  
Effective Potential ◽  
Modified Gravity ◽  
Palatini Formalism ◽  
Slow Roll ◽  
Slow Roll Inflation

Slow-roll inflation is analyzed in the context of modified gravity within the Palatini formalism. As shown in the literature, inflation in this framework requires the presence of non-traceless matter; otherwise, it does not occur just as a consequence of the nonlinear gravitational terms of the action. Nevertheless, by including a single scalar field that plays the role of the inflaton, slow-roll inflation can be performed in these theories, where the equations lead to an effective potential that modifies the dynamics. We obtain the general slow-roll parameters and analyze a simple model to illustrate the differences introduced by the gravitational terms under the Palatini approach, and the modifications on the spectral index and the tensor to scalar ratio predicted by the model.

scholarly journals Generalized slow-roll inflation

2000 ◽  
Vol 269 (4) ◽  
pp. 209-213 ◽  
Author(s):  
Valerio Faraoni
Keyword(s):  
Slow Roll ◽  
Slow Roll Inflation

scholarly journals Inflationary cosmology in unimodular F(T) gravity

2017 ◽  
Vol 32 (21) ◽  
pp. 1750114 ◽  
Author(s):  
Kazuharu Bamba ◽  
Sergei D. Odintsov ◽  
Emmanuel N. Saridakis
Keyword(s):  
Spectral Index ◽  
Teleparallel Gravity ◽  
Specific Model ◽  
Inflationary Cosmology ◽  
Model Parameters ◽  
De Sitter ◽  
Reconstruction Procedure ◽  
Additional Advantage ◽  
Slow Roll ◽  
Good Agreement

We investigate the inflationary realization in the context of unimodular F(T) gravity, which is based on the F(T) modification of teleparallel gravity, in which one imposes the unimodular condition through the use of Lagrange multipliers. We develop the general reconstruction procedure of the F(T) form that can give rise to a given scale-factor evolution, and then we apply it in the inflationary regime. We extract the Hubble slow-roll parameters that allow us to calculate various inflation-related observables, such as the scalar spectral index and its running, the tensor-to-scalar ratio, and the tensor spectral index. Then, we examine the particular cases of de Sitter and power-law inflation, of Starobinsky inflation, as well as inflation in a specific model of unimodular F(T) gravity. As we show, in all cases the predictions of our scenarios are in a very good agreement with Planck observational data. Finally, inflation in unimodular F(T) gravity has the additional advantage that it always allows for a graceful exit for specific regions of the model parameters.

scholarly journals THE N-TACHYON ASSISTED INFLATION

2007 ◽  
Vol 22 (36) ◽  
pp. 2737-2748 ◽  
Author(s):  
HARVENDRA SINGH
Keyword(s):  
Open String ◽  
Slow Roll ◽  
Slow Roll Inflation

In continuation of the papers hep-th/0505012 and hep-th/0508101 we investigate the consequences when N open-string tachyons roll down simultaneously. We demonstrate that the N-tachyon system coupled to gravity does indeed give rise to the assisted slow-roll inflation.

scholarly journals NATURAL SLOW-ROLL INFLATION

1996 ◽  
Vol 11 (08) ◽  
pp. 631-646 ◽  
Author(s):  
R.F. LANGBEIN ◽  
K. LANGFELD ◽  
H. REINHARDT ◽  
L. von SMEKAL
Keyword(s):  
Phase Change ◽  
Early Universe ◽  
Slow Roll ◽  
Slow Roll Inflation

It is shown that the nonperturbative dynamics of a phase change to the nontrivial phase of λφ4-theory in the early universe can give rise to slow-rollover inflation without recourse to unnaturally small couplings.

scholarly journals NONCOMMUTATIVE DECRUMPLING INFLATION AND RUNNING OF THE SPECTRAL INDEX

2005 ◽  
Vol 14 (03n04) ◽  
pp. 621-633 ◽  
Author(s):  
FOROUGH NASSERI ◽  
S. A. ALAVI
Keyword(s):  
Noncommutative Geometry ◽  
Spectral Index ◽  
Time Variability ◽  
Inflation Model ◽  
Slow Roll ◽  
Spatial Dimensions

We present a new inflation model, known as noncommutative decrumpling inflation, in which space has noncommutative geometry with time variability of the number of spatial dimensions. Within the framework of noncommutative decrumpling inflation, we compute both the spectral index and its running. Our results show the effects of both time variability of the number of spatial dimensions and noncommutative geometry on the spectral index and its running. Two classes of examples have been studied and comparisons made with the standard slow-roll formulae. We conclude that the effects of noncommutative geometry on the spectral index and its running are much smaller than the effects of time variability of spatial dimensions.

scholarly journals Measuring the effects of loop quantum cosmology in the CMB data

2017 ◽  
Vol 26 (12) ◽  
pp. 1743023 ◽  
Author(s):  
Spyros Basilakos ◽  
Vahid Kamali ◽  
Ahmad Mehrabi
Keyword(s):  
Power Spectrum ◽  
Spectral Index ◽  
Excellent Agreement ◽  
Quantum Cosmology ◽  
Loop Quantum Cosmology ◽  
Alternative Scenario ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Robust Prediction ◽  
Scalar Fluctuation

In this paper we investigate the observational signatures of Loop Quantum Cosmology (LQC) in the CMB data. First, we concentrate on the dynamics of LQC and we provide the basic cosmological functions. We then obtain the power spectrum of scalar and tensor perturbations in order to study the performance of LQC against the latest CMB data. We find that LQC provides a robust prediction for the main slow-roll parameters, like the scalar spectral index and the tensor-to-scalar fluctuation ratio, which are in excellent agreement within [Formula: see text] with the values recently measured by the Planck collaboration. This result indicates that LQC can be seen as an alternative scenario with respect to that of standard inflation.

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