# Théorie

# Fake hair for black holes

We will review modified gravity theories and in particular scalar

tensor theories, the mildest of modifications, where

we have an additional interacting scalar field coupling to the metric

# Holographic RG flows and Quantum Effective Actions

# Spectral distortions in the cosmic microwave background polarization

Deviations of the cosmic microwave background (CMB) spectrum from the one of a blackbody, so-called spectral distortions, have recently emerged as a powerful probe of many physical phenomena, ranging from inflation to dark matter and reionization. However, most studies so far have concentrated on the distortions of the monopole of the CMB intensity, while future missions will characterize the spectrum of its anisotropies, both in intensity and in polarization.

# The confining trailing string

We extend the holographic trailing string picture of a heavy quark diffusing through the plasma to the case of a bulk geometry dual to a confining gauge theory. We compute the classical trailing confining string solution for a static as well as a uniformly moving quark. The trailing string is infinitely extended and approaches a confining horizon, situated at a critical value of the radial coordinate, along one of the space-time directions, breaking boundary rotational invariance.

# Inflation, BICEP2, and an interesting discrepancy with Planck

# An introduction to the non perturbative renormalization group: method and some applications in statistical mechanics

An introduction to the modern version of Wilson's renormalization group will be given together with the two nonperturbative approximation schemes that have effectively been implemented (the derivative expansion and the Blaizot-Mendez-Wschebor scheme). The O(N) scalar models will be our favourite playground. Then, some results obtained in out of equilibrium statistical mechanics will be presented showing that fully nonperturbative physics can be captured by the nonperturbative renormalization group.

# Fundamental Physics and Nuclear Structure

Much of the fundamental physics we have learned about in recent years was uncovered in low-energy experiments. More low-energy experiments are in progress and many require that nuclear effects be untangled from the fundamental physics we are trying to probe. I review the issue and attempts to understand the relevant nuclear physics in three kinds of experimental searches: for neutrinoless double beta decay, for new sources of CP violation through nonzero atomic electric dipole moments, and for dark matter particles through scattering from ordinary matter.

# Charged Chern-Simons AdS black holes

We found the most general spherically symmetric, static black hole solution for Chern-Simons gravity based on a simple extension of the AdS algebra, that is, AdS x U(1). The corresponding gauge connection contains gravitational fields describing a Riemann-Cartan manifold with electromagnetic matter field. When the electromagnetic field and some components of the torsion are switched off, solution reproduces the known ones found in the literature. For other choices of the torsion components, our solution is physically different from the already known ones.

# Cubic interactions and Symmetries of Higher-spin field theories

# Localized features in the primordial spectra from heavy physics

Primordial density fluctuations provide one of a few ways to probe the high energy physics behind inflation. In this talk, we discuss the possibility that we could obtain some hints of the heavy physics during inflation by analyzing local features in the spectra of the primordial fluctuations.