Case for kinetically dominated initial conditions for inflation

Hergt, L. T.; Handley, Will; Hobson, M.; Lasenby, A.

doi:10.1103/physrevd.100.023502

Cited by 30 publications

(21 citation statements)

References 34 publications

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“…It is interesting to note that this robust feature was also shown to be true generically for the universe emerging from an initial singularity in a non-inflating state where the kinetic energy of the inflaton well dominates its potential energy[46][47][48].…”

mentioning

confidence: 79%

Genericness of pre-inflationary dynamics and probability of the desired slow-roll inflation in modified loop quantum cosmologies

Singh

Wang

2019

Phys. Rev. D

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We study the evolution of spatially flat Friedmann-Lemaître-Robertson-Walker universe for chaotic and Starobinsky potentials in the framework of modified loop quantum cosmologies. These models result in a non-singular bounce as in loop quantum cosmology, but with far more complex modified Friedmann dynamics with higher order than quadratic terms in energy density. For the kinetic energy dominated bounce, we obtain analytical solutions using different approximations and compare with numerical evolution for various physical variables. The relative error turns out to be less than 0.3% in the bounce regime for both of the potentials. Generic features of dynamics, shared with loop quantum cosmology, are established using analytical and numerical solutions. Detailed properties of three distinct phases in dynamics separating bounce regime, transition stage and inflationary phase are studied. For the potential energy dominated bounce, we qualitatively describe its generic features and confirm by simulations that they all lead to the desired slow-roll phase in the chaotic inflation. However, in the Starobinsky potential, the potential energy dominated bounce cannot give rise to any inflationary phase. Finally, we compute the probability for the desired slowroll inflation to occur in the chaotic inflation and as in loop quantum cosmology, find a very large probability for the universe to undergo inflation. c 3ρ I c (1 − 5γ 2 ) 1 + 1 − ρ/ρ I c 2 , (2.15)

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mentioning

confidence: 79%

Genericness of pre-inflationary dynamics and probability of the desired slow-roll inflation in modified loop quantum cosmologies

Singh

Wang

2019

Phys. Rev. D

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“…Inflationary models including kinetic dominance are already being investigated, e.g. by [30] and [31]. In this scenario, the cosmological background in terms of N is integrated from the initial state…”

Section: A Model Using Kinetic Dominancementioning

confidence: 99%

Efficient method for solving highly oscillatory ordinary differential equations with applications to physical systems

Agocs

Handley

Lasenby

et al. 2020

Phys. Rev. Research

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We present a novel numerical routine (oscode) with a C++ and Python interface for the efficient solution of one-dimensional, second-order, ordinary differential equations with rapidly oscillating solutions. The method is based on a Runge-Kutta-like stepping procedure that makes use of the Wentzel-Kramers-Brillouin (WKB) approximation to skip regions of integration where the characteristic frequency varies slowly. In regions where this is not the case, the method is able to switch to a madeto-measure Runge-Kutta integrator that minimises the total number of function evaluations. We demonstrate the effectiveness of the method with example solutions of the Airy equation and an equation exhibiting a burst of oscillations, discussing the error properties of the method in detail. We then show the method applied to physical systems. First, the one-dimensional, time-independent Schrödinger equation is solved as part of a shooting method to search for the energy eigenvalues for a potential with quartic anharmonicity. Then, the method is used to solve the Mukhanov-Sasaki equation describing the evolution of cosmological perturbations, and the primordial power spectrum of the perturbations is computed in different cosmological scenarios. We compare the performance of our solver in calculating a primordial power spectrum of scalar perturbations to that of BINGO, an efficient code specifically designed for such applications, and find that our method performs better.

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“…If one is to invoke an inflationary phase in order to explain the observed present-day flatness, one cannot assume that the universe was flat at the start of inflation, and the presence of any curvature is arguably incompatible with eternal inflation. Furthermore, the observation of any amount of presentday curvature strongly constrains the total amount of inflation, providing a powerful justification for just-enoughinflation theories [19][20][21][22][23][24] In the traditional curved KΛCDM cosmology, a simple (A s , n s ) parametric form for the primordial power spec- * wh260@mrao.cam.ac.uk † https://www.kicc.cam.ac.uk/directory/wh260 trum is usually assumed [4,5]:…”

Section: Introductionmentioning

confidence: 99%

Primordial power spectra for curved inflating universes

Handley

2019

Phys. Rev. D

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Exact numerical primordial primordial power spectra are computed and plotted for the for the best-fit Planck 2018 curved universe parameters. It is found that the spectra have generic cut-offs and oscillations within the observable window for the level of curvature allowed by current CMB measurements and provide a better fit to current data. Derivations for the Mukhanov-Sasaki equation for curved universes are presented and analysed, and theoretical implications for the quantum and classical initial conditions for inflation are discussed within the curved regime.

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Case for kinetically dominated initial conditions for inflation

Cited by 30 publications

References 34 publications

Genericness of pre-inflationary dynamics and probability of the desired slow-roll inflation in modified loop quantum cosmologies

Genericness of pre-inflationary dynamics and probability of the desired slow-roll inflation in modified loop quantum cosmologies

Efficient method for solving highly oscillatory ordinary differential equations with applications to physical systems

Primordial power spectra for curved inflating universes

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