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Quantum corrections to cosmic perturbations for a bouncing background

Hector Hernandez-Hernandez*

Hugo A. Morales-Técotl† and Gustavo Sanchez-Herrera‡

  • Universidad Autonoma de Chihuahua, Facultad de Ingenieria, Nuevo Campus Universitario, Chihuahua 31125, México and Universidad Autonoma Metropolitana Cuajimalpa, Departamento de Matematicas Aplicadas y Sistemas, Vasco de Quiroga 4871, Ciudad de México 05348, México

  • Universidad Autonoma Metropolitana Unidad Iztapalapa, San Rafael Atlixco 186, CP 09340, Ciudad de México, México

  • *Contact author: hhernandez@uach.mx
  • †Contact author: hugo@xanum.uam.mx
  • ‡Contact author: cbi2233805002@xanum.uam.mx
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Phys. Rev. D 114, 084010 – Published 2 October, 2026

DOI: https://doi.org/10.1103/3r76-5fn5

Abstract

We compute second-order quantum dispersions and correlations corrections, within an effective framework describing a single scalar perturbation mode propagating on a bouncing Loop Quantum Cosmology (LQC) background. Using an effective quantization approach in which quantum moments extend the classical phase space as new dynamical degrees of freedom and incorporating the cosmic bounce through holonomy corrections in the μ0 scheme, we derive a coupled set of effective equations of motion for the expectation values and second-order quantum moments of both the gravitational and scalar sectors evolving with respect to a clock scalar field. Within the test-field approximation and for a vanishing scalar potential, the quantum moment equations reduce to a third-order ordinary differential equation for the mean squared deviation Gvv of the Mukhanov-Sasaki variable in a de Sitter background with LQC bounce. Treating the effect of bounce as a perturbation of the solution, we construct the corresponding correction to the dimensionless curvature power spectrum. The leading correction is suppressed by the sixth power of the Planck length producing a scale-dependent enhancement δPR∝(kℓPl)6 that modifies the spectral index by δns∼6(kℓPl)6≪1 for all cosmologically observable modes, in full consistency with current observational constraints. Numerical evolution of the full coupled system reveals a conditional ultraviolet regularization of the bounce-induced spectrum: the gravitational quantum moments generate a damping mechanism that suppresses the scalar perturbation amplitude after the bounce. Including cross-sector quantum correlations amplifies perturbation modes and introduces numerical instabilities at high wave numbers, signaling the limits of the second-order truncation in the ultraviolet.

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Information

Phys. Rev. D 114, 084010– Published 2 October, 2026
  • Received 20 May 2026
  • Accepted 3 September 2026
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