230 citations · 3.3k across the 75 of their papers we have counts for
29 papers · 1 filter
Hamiltonian formalism for cosmological perturbations: fixing the gauge
Danilo Artigas, Julien Grain, Vincent Vennin
Cosmological perturbation theory is an example of a gauge theory, where gauge transformations correspond to changes in the space-time coordinate system. To determine physical quant…
Quantum recoherence in the early universe
Thomas Colas, Julien Grain, Vincent Vennin
Despite being created through a fundamentally quantum-mechanical process, cosmological structures have not yet revealed any sign of genuine quantum correlations. Among the obstruct…
Quantum fields in the background spacetime of a loop quantum gravity black hole
Flora Moulin, Killian Martineau, Julien Grain +1
The description of black holes in loop quantum gravity is a hard and tricky task. In this article, we focus on a minisuperspace approach based on a polymerization procedure. We con…
A first step towards the inflationary trans-planckian problem treatment in Loop Quantum Cosmology
Killian Martineau, Aurélien Barrau, Julien Grain
For most initial conditions, cosmologically relevant physical modes were trans-planckian at the bounce time, often by many magnitude orders. We improve the usual loop quantum cosmo…
Stochastic inflation in phase space: Is slow roll a stochastic attractor?
Julien Grain, Vincent Vennin
An appealing feature of inflationary cosmology is the presence of a phase-space attractor, "slow roll", which washes out the dependence on initial field velocities. We investigate…
A new look at scalar perturbations in loop quantum cosmology: (un)deformed algebra approach using self dual variables
Jibril Ben Achour, Suddhasattwa Brahma, Julien Grain +1
Scalar cosmological perturbations in loop quantum cosmology (LQC) is revisited in a covariant manner, using self dual Ashtekar variables. For real-valued Ashtekar-Barbero variables…