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Early Universe: inflation and cosmological perturbations
David Langlois
After a brief summary of general relativity and cosmology, we present the basic concepts underlying inflation, the currently best motivated models for the early Universe. We descri…
Cosmological perturbations from multi-field inflation
David Langlois
We briefly review the standard derivation of the spectra of cosmological perturbations in the simplest models of inflation. We then consider models with several scalar fields, desc…
Non-linear isocurvature perturbations and non-Gaussianities
David Langlois, Filippo Vernizzi, David Wands
We study non-linear primordial adiabatic and isocurvature perturbations and their non-Gaussianity. After giving a general formulation in the context of an extended delta N-formalis…
Primordial perturbations and non-Gaussianities in DBI and general multi-field inflation
David Langlois, Sebastien Renaux-Petel, Daniele A. Steer +1
We study cosmological perturbations in general inflation models with multiple scalar fields and arbitrary kinetic terms, with special emphasis on the multi-field extension of Dirac…
Primordial fluctuations and non-Gaussianities in multi-field DBI inflation
David Langlois, Sebastien Renaux-Petel, Daniele A. Steer +1
We study Dirac-Born-Infeld (DBI) inflation models with multiple scalar fields. We show that the adiabatic and entropy modes propagate with a common effective sound speed and are th…
Perturbations in generalized multi-field inflation
David Langlois, Sébastien Renaux-Petel
We study the linear perturbations of multi-field inflationary models governed by a Lagrangian which is a general function of the scalar fields and of a global kinetic term combinin…