Cosmology with peculiar velocities

The Universe is not homogenous. Since the early times, its structures have grown and moved under the laws of gravity. By measuring these motions today we are able to trace the spatial distribution of dark matter and accurately map the Universe. The comparison of the recovered large scale structures with the predictions of the concordance model of cosmology is then a powerful test of the laws of expansion and gravity.

The Diffuse Supernova Neutrino Background in Super-Kamiokande

Cosmology as a CFT1

Over the last decades, the emergence of conformal symmetry in gravitational systems has provided a powerful tool to investigate new aspects in classical, semi-classical and quantum general relativity.

Observational signatures of multifield inflation

Slow-roll single-field inflation constitutes the main paradigm of the
Early Universe. But this model suffers from a number of conceptual issues
that naturally lead to the consideration of multifield models of
inflation with curved field space, that have recently been under scrutiny
as realistic realizations of high-energy physics in the Early Universe.
I will show that the non-trivial internal geometry reshuffles
observational predictions from inflation, at the level of the background
(geometrical destabilisation of inflation), of linear

Relieving the Hubble tension with primordial magnetic fields

Seminar Thibaut Houdy: KATRIN, from neutrino mass to Dark Matter

The KATRIN (Karlsruhe Tritium Neutrino) experiment investigates the energetic endpoint of the tritium beta-decay spectrum to determine the effective mass of the electron anti-neutrino. The collaboration reported its first neutrino mass result in fall 2019. Its unprecedented tritium source luminosity and spectroscopic quality make it a unique instrument to also search for physics beyond the standard model such as eV or keV sterile neutrinos.

Observations with LHAASO-1/2 and the Construction Status

This is a joint seminar with the Institute of High Energy Physics in Beijing.

Composite and holographic axions

The idea that low energy fields such as Gravitons or Axions can be 
thought of as composite particles has been entertained since a long 
time. We revisit this idea motivated by the AdS/CFT correspondence. We 
focus in the case of axions and show that hidden sectors coupled to SM 
fields may provide an emergent axionic field that is a composite of the 
hidden fields (instanton density). This is a more general phenomenon 
beyond holographic theories. We study the general properties of such an 
"emergent axion", without a PQ symmetry. The construction goes beyond

Euclidean Wormholes and Holography

Inflation and Geometry

Inflation, an era of accelerated expansion of the universe prior to the radiation phase, constitutes the paradigm of primordial cosmology. Within this paradigm, the simplest single-field slow-roll models economically explain all curent data. However, the sensitivity of inflation to Planck scale physics, and the fact that ultraviolet completions of inflation invariably involve extra fields coupled to the inflaton, indicate that these models constitute at best a phenomenological description that emerges from a more realistic physical framework.

LABORATOIRE

ASTROPARTICULE & COSMOLOGIE

Séminaire