Non-singular bounce scenarios in loop quantum cosmology and the effective field description

• Published in: Journal of cosmology and astroparticle physics Vol. 2014; no. 3; pp. 1 - 19
• Main Authors: Cai, Yi-Fu, Wilson-Ewing, Edward
• Format: Journal Article
• Language: English
• Published: United States 01.03.2014
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Bouncing; Cosmology; DUSTS; ENERGY DENSITY; GENERAL RELATIVITY THEORY; Ghosts; Inflation; MATTER; Perturbation methods; PERTURBATION THEORY; QUANTUM COSMOLOGY; QUANTUM GRAVITY; SCALAR FIELDS; SCALARS; UNIVERSE
• ISSN: 1475-7516; 1475-7516
• DOI: 10.1088/1475-7516/2014/03/026

A non-singular bouncing cosmology is generically obtained in loop quantum cosmology due to non-perturbative quantum gravity effects. A similar picture can be achieved in standard general relativity in the presence of a scalar field with a non-standard kinetic term such that at high energy densities the field evolves into a ghost condensate and causes a non-singular bounce. During the bouncing phase, the perturbations can be stabilized by introducing a Horndeski operator. Taking the matter content to be a dust field and an ekpyrotic scalar field, we compare the dynamics in loop quantum cosmology and in a non-singular bouncing effective field model with a non-standard kinetic term at both the background and perturbative levels. We find that these two settings share many important properties, including the result that they both generate scale-invariant scalar perturbations. This shows that some quantum gravity effects of the very early universe may be mimicked by effective field models.