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An adiabatic approach to the trans-Planckian problem in loop quantum cosmology

Rita B. Neves
University of Sheffield

One of the criticisms of the inflationary paradigm is that scales that are observable today were trans-Planckian at the onset of inflation. This questions the validity of standard results regarding the primordial power spectrum. Standard cosmology also ignores pre-inflationary dynamics, since it loses predictability close to the initial singularity. Loop Quantum Cosmology (LQC) is an approach to the quantisation of cosmological models. It provides effective pre-inflationary dynamics where the big-bang singularity is resolved in terms of a quantum bounce, that connects a contracting epoch of the Universe with an expanding one. In this talk, we investigate the trans-Planckian problem in two models of LQC. We find that one of the models avoids the issue altogether by generating less e-folds of inflation, such that the observable modes never become trans-Planckian. On the other hand, the other model suffers from this problem, as observable modes become trans-Planckian during a time when they lose adiabaticity, making their primordial power spectrum susceptible to changes due to trans-Planckian physics.

2024 July 16, 15:00

Faculdade de Ciências da Universidade de Lisboa (C8.2.06)
Campo Grande, 1749-016 Lisboa

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia