Manifestly gauge-invariant cosmological perturbation theory from full loop quantum gravity
| Autor: | Hongguang Liu, Haida Li, Muxin Han |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
High Energy Physics - Theory
Physics 010308 nuclear & particles physics Long wavelength limit Graviton FOS: Physical sciences Semiclassical physics General Relativity and Quantum Cosmology (gr-qc) Loop quantum gravity 01 natural sciences General Relativity and Quantum Cosmology High Energy Physics - Theory (hep-th) 0103 physical sciences Path integral formulation Cosmological perturbation theory Quantum gravity Phase space formulation 010306 general physics Mathematical physics |
| Zdroj: | Physical Review D. 102 |
| ISSN: | 2470-0029 2470-0010 |
| DOI: | 10.1103/physrevd.102.124002 |
| Popis: | We apply the full theory of Loop Quantum Gravity (LQG) to cosmology and present a top-down derivation of gauge-invariant cosmological perturbation theory from quantum gravity. The derivation employs the reduced phase space formulation of LQG and the new discrete path integral formulation defined in arXiv:1910.03763. We demonstrate that in the semiclassical approximation and continuum limit, the result coincides with the existing formulation of gauge-invariant cosmological perturbation theory in e.g. arXiv:0711.0117. Time evolution of cosmological perturbations is computed numerically from the new cosmological perturbation theory of LQG, and various power spectrums are studied for scalar mode and tensor mode perturbations. Comparing these power spectrums with predictions from the classical theory demonstrate corrections in the ultra-long wavelength regime. These corrections are results from the lattice discretization in LQG. In addition, tensor mode perturbations at late time demonstrate the emergence of spin-2 gravitons as low energy excitations from LQG. The graviton has a modified dispersion relation and reduces to the standard graviton in the long wavelength limit. 26 pages, 16 figures. ILQGS talk: http://relativity.phys.lsu.edu/ilqgs/han041420.mp4. Mathematica files can be downloaded from https://github.com/LQG-Florida-Atlantic-University/cos_pert |
| Databáze: | OpenAIRE |
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