Time-dependent mass of cosmological perturbations in the hybrid and dressed metric approaches to loop quantum cosmology

Elizaga de Navascués B, Martin de Blas D, Mena Marugan G (2018)

Publication Language: English

Publication Type: Journal article, Original article

Publication year: 2018

Journal

Physical Review D - Particles, Fields, Gravitation and Cosmology American Physical Society

Pages Range: 043523-1 - 043523-15

Article Number: 043523

Journal Issue: 97

URI: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.97.043523

DOI: 10.1103/PhysRevD.97.043523

Abstract

Loop quantum cosmology has recently been applied in order to extend the analysis of primordial perturbations to the planck era and discuss the possible effects of quantum geometry on the cosmic microwave background. Two approaches to quantum cosmology with admissible ultraviolet behaviors leading to predictions that are compatible with observations are the so-called hybrid and dressed metric approaches. The evolution of the tensor and scalar perturbations are somewhat different. When backreaction is neglected, the discrepancy appears only in the time-dependent mass term of the corresponding field equations. We explain the origin of this difference, arising from the distinct quantization procedures. Besides, given the privileged role that the big bounce plays in the quantum cosmology loop, eg as a natural instant of time to set initial conditions for the perturbations, so we analyze the positivity of the time-dependent mass when this bounce occurs. While the mass of the tensor perturbations is positive in the hybrid approach, the kinetic contribution to the energy density of the inflation dominates over its potential, as well as to a large area of the situation, while this mass is always nonpositive in the dressed metric approach. Similar results are demonstrated for the scalar perturbations in a sector of background that includes the kinetically dominated ones; namely, the mass then is positive for the hybrid approach, it is becoming negative in the dressed metric case. More precisely, this last statement is strictly valid when the potential is quadratic for values of the inflation.

Authors with CRIS profile

Beatriz Elizaga de Navascués Chair for Theoretical Physics III (Quantum Gravity)

Involved external institutions

Spanish National Research Council / Consejo Superior de Investigaciones Científicas (CSIC)

Spain (ES)

How to cite

APA:

Elizaga de Navascués, B., Martin de Blas, D., & Mena Marugan, G. (2018). Time-dependent mass of cosmological perturbations in the hybrid and dressed metric approaches to loop quantum cosmology. Physical Review D - Particles, Fields, Gravitation and Cosmology, 97, 043523-1 - 043523-15. https://doi.org/10.1103/PhysRevD.97.043523

MLA:

Elizaga de Navascués, Beatriz, Daniel Martin de Blas, and Guillermo Mena Marugan. "Time-dependent mass of cosmological perturbations in the hybrid and dressed metric approaches to loop quantum cosmology." Physical Review D - Particles, Fields, Gravitation and Cosmology 97 (2018): 043523-1 - 043523-15.

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