Tachyon field in loop cosmology

Xiao, Kui

doi:10.1016/j.physletb.2020.135859

Cited by 6 publications

(7 citation statements)

References 41 publications

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“…For other potentials, similar results can be obtained, as long as at the bounce the evolution of the Universe is dominated by the kinetic energy of the inflaton w(ϕ B ) ≃ 1 (Li et al, 2019;Xiao, 2020).…”

Section: Universal Properties Of Mlqc-i/ii Modelssupporting

confidence: 71%

Phenomenological Implications of Modified Loop Cosmologies: An Overview

Singh

Wang

2021

Front. Astron. Space Sci.

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In this paper, we first provide a brief review of the effective dynamics of two recently well-studied models of modified loop quantum cosmologies (mLQCs), which arise from different regularizations of the Hamiltonian constraint and show the robustness of a generic resolution of the big bang singularity, replaced by a quantum bounce due to non-perturbative Planck scale effects. As in loop quantum cosmology (LQC), in these modified models the slow-roll inflation happens generically. We consider the cosmological perturbations following the dressed and hybrid approaches and clarify some subtle issues regarding the ambiguity of the extension of the effective potential of the scalar perturbations across the quantum bounce, and the choice of initial conditions. Both of the modified regularizations yield primordial power spectra that are consistent with current observations for the Starobinsky potential within the framework of either the dressed or the hybrid approach. But differences in primordial power spectra are identified among the mLQCs and LQC. In addition, for mLQC-I, striking differences arise between the dressed and hybrid approaches in the infrared and oscillatory regimes. While the differences between the two modified models can be attributed to differences in the Planck scale physics, the permissible choices of the initial conditions and the differences between the two perturbation approaches have been reported for the first time. All these differences, due to either the different regularizations or the different perturbation approaches in principle can be observed in terms of non-Gaussianities.

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Section: Universal Properties Of Mlqc-i/ii Modelssupporting

confidence: 71%

Phenomenological Implications of Modified Loop Cosmologies: An Overview

Singh

Wang

2021

Front. Astron. Space Sci.

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“…For other potentials, similar results can be obtained, as long as at the bounce the evolution of the universe is dominated by the kinetic energy of the inflaton w(φ B ) 1 [74,102]. In each of these three phases, the evolutions of a(t) and φ(t) can be well approximated by analytical solutions.…”

Section: Universal Properties Of Mlqc-i/ii Modelssupporting

confidence: 61%

Phenomenological implications of modified loop cosmologies: an overview

Li,

Singh,

Wang

2021

Preprint

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“…The properties of the tachyon field as a subclass of k-essence were first studied in LQC in [65]. It was then further explored in [66][67][68], where the authors found that the model could describe successful inflation with a sufficient number of a e-folds. They also showed that the quantum dynamical solution has attractive behaviour.…”

Section: Introductionmentioning

confidence: 99%

Background Dynamics of Pre-inflationary Scenario in Brans-Dicke Loop Quantum Cosmology*

Sharma¹,

Zhu²,

Wang³

2019

Commun. Theor. Phys.

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Recently the background independent nonperturbative quantization has been extended to various theories of gravity and the corresponding quantum effective cosmology has been derived, which provides us with necessary avenue to explore the pre-inflationary dynamics. Brans-Dicke (BD) loop quantum cosmology (LQC) is one of such theories whose effective background dynamics is considered in this article. Starting with a quantum bounce, we explore the pre-inflationary dynamics of a universe sourced by a scalar field with the Starobinsky potential in BD-LQC. Our study is based on the idea that though Einstein's and Jordan's frames are classically equivalent up to a conformal transformation in BD theory, this is no longer true after quantization. Taking the Jordan frame as the physical one we explore in detail the bouncing scenario which is followed by a phase of a slow roll inflation. The three phases of the evolution of the universe, namely, bouncing, transition from quantum bounce to classical universe, and the slow roll inflation, are noted for an initially kinetic energy dominated bounce. In addition, to be consistent with observations, we also identify the allowed phase space of initial conditions that would produce at least 60 e-folds of expansion during the slow roll inflation. *

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Tachyon field in loop cosmology

Cited by 6 publications

References 41 publications

Phenomenological Implications of Modified Loop Cosmologies: An Overview

Phenomenological Implications of Modified Loop Cosmologies: An Overview

Phenomenological implications of modified loop cosmologies: an overview

Background Dynamics of Pre-inflationary Scenario in Brans-Dicke Loop Quantum Cosmology*

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