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Hybrid Loop Quantum Cosmology: An Overview

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arxiv 2011.04559 v3 pith:P4MV2WXC submitted 2020-11-09 gr-qc

Hybrid Loop Quantum Cosmology: An Overview

classification gr-qc
keywords quantumloopcosmologycosmologicalhybridquantizationapproachbackground
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Loop Quantum Gravity is a nonperturbative and background independent program for the quantization of General Relativity. Its underlying formalism has been applied successfully to the study of cosmological spacetimes, both to test the principles and techniques of the theory and to discuss its physical consequences. These applications have opened a new area of research known as Loop Quantum Cosmology. The hybrid approach addresses the quantization of cosmological systems that include fields. This proposal combines the description of a finite number of degrees of freedom using Loop Quantum Cosmology, typically corresponding to a homogeneous background, and a Fock quantization of the field content of the model. In this review we first present a summary of the foundations of homogeneous Loop Quantum Cosmology and we then revisit the hybrid quantization approach, applying it to the study of Gowdy spacetimes with linearly polarized gravitational waves on toroidal spatial sections, and to the analysis of cosmological perturbations in preinflationary and inflationary stages of the Universe. The main challenge is to extract predictions about quantum geometry effects that eventually might be confronted with cosmological observations. This is the first extensive review of the hybrid approach in the literature on Loop Quantum Cosmology.

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Cited by 5 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Prism Effect in Quantum Gravity

    gr-qc 2026-07 conditional novelty 7.0

    Electromagnetic backreaction on quantum geometry in LQC makes the photon group velocity mode-dependent and subluminal, a 'prism effect' that vanishes at low energies.

  2. Prism Effect in Quantum Gravity

    gr-qc 2026-07 unverdicted novelty 6.0

    Extended Born-Oppenheimer coupling of the EM field to quantum geometry yields chromatic dispersion of light—a prism effect proposed as an all-energy quantum-gravity probe on a quantum FLRW background.

  3. Effects of the ekpyrotic mechanism on inflationary phase in loop quantum cosmologies

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    In LQC and mLQC-I, tuned ekpyrotic-plus-inflation potentials can yield w>1 at the bounce and at least 60 e-folds of post-bounce inflation.

  4. Quasi-dust ekpyrotic scenario in Loop Quantum Cosmology

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    A quasi-dust ekpyrotic two-field model in Loop Quantum Cosmology produces viable primordial power spectra via coupled scalar and tensor perturbations.

  5. Stable initial conditions and analytical investigations of cosmological perturbations in a modified loop quantum cosmology

    gr-qc 2025-05 unverdicted novelty 5.0

    A stable initial state is identified in mLQC-I that diagonalizes the Hamiltonian and minimizes particle creation, with mode functions approximated analytically by Airy or cylindrical functions whose constants are fixe...