Recent results about vector- and multi-Galileon theories

Galileon models follow the Horndeski systematic construction to couple additional fields to gravity in order to modify the Einstein equations. There were first investigated from 2009 in the case of a single scalar field. Thus, there have been an increasing interest in similar models involving either a vector field or several scalar or vector fields. During this talk, I will present results from these different topics.

Exotic RG flows from holography

The AdS/CFT correspondence, a useful tool in the study of strongly coupled physics, relates fields, including gravity, in a d+1 dimensional asymptotically AdS space-time to operators in a d-dimensional Conformal Field Theory (CFT), in a one-to-one correspondence. The extra spatial dimension appearing in the gravitational side of the duality, the holographic dimension, is in correspondence with an energy scale on the QFT side: fields evolving along the holographic dimension are dual to renormalization group flows of couplings to the dual QFT operators.

Helicity coherence in binary neutron star mergers and non-linear feedback

Neutrino flavor conversion studies based on astrophysical environments usually implement neutrino mixings, neutrino interactions with matter and neutrino self-interactions. In anisotropic media, the most general mean-field treatment includes neutrino mass contributions as well, that introduce a coupling between neutrinos and antineutrinos termed helicity or spin coherence. We discuss resonance conditions for helicity coherence for Majorana neutrinos. We explore the role of these mean-field contributions on flavor evolution in the context of a binary neutron star merger remnant.

Leptonic CP Violation in Minimal Seesaw Models

Within the next decade or so, neutrino oscillation experiments will (hopefully) pin down the amount of CP violation in the Standard Model lepton sector. From the viewpoint of theory, this exciting prospect stimulates several important questions: How much CP violation do we actually expect from a theoretical perspective? That is, what predictions can we make for the outcome of upcoming experiments?

The QCD axion, precisely

The QCD axion is probably the most robust solution to the strong CP
problem and a natural dark matter candidate. While its properties, such as the
mass and the couplings, are mostly determined by non-perturbative QCD effects
I will present recent computations demonstrating that they can be reliably
extracted with percent accuracy, which is important for the theory
interpretation of experimental results. I will also discuss some recent
lattice QCD results highlighting a departure from the usual instanton

Naturalness in the Aristotelian Spacetime

Some of the most fundamental puzzles in theoretical physics can be phrased as puzzles of technical naturalness. Examples include the cosmological constant problem, the Higgs mass hierarchy problem, the linear scaling of resistivity with temperature in the strange metal phase of high-tempterature superconductors etc. I will re-examine the notion of technical naturalness in systems whose short-distance behavior exhibits nonrelativistic symmetries of "Aristotelian spacetime", pointing out various surprises and novelties, with possible applications in particle phenomenology, cosmology and con

Carroll Symmetry, Gravitational Memory and Soft Gravitons

In the first part of my talk I will discuss the notion of
relativity principle, kinematic algebras, the classification of Leblond and Bacry I will define
the Carroll group and its extensions. I will gave Applications to very
special Relativity String theory and the BMS algebras. In the second part I will discuss
plane gravitational waves and how the a subgroup of the Carroll group acts and how this can be used
illuminate the currently fashionable topics of gravitational memory and soft

Making the halo of Andromeda with the QCD Axion?

The QCD axion is a curious Dark Matter candidate, having a mass like the neutrino, but behaving as Cold Dark Matter during linear structure formation. I will review how this occurs, and speculate on the interesting question of how axions make galactic halos during non-linear structure formation, and whether observations could distinguish them from WIMPs.

The SM Higgs as the origin of the hot Big Bang

Under general circumstances, the Standard Model (SM) Higgs is excited in the form of a condensate during or towards the end of inflation. The Higgs condensate is then forced to decay afterwards — due to non-perturbative effects — into the rest of the SM species. I will present the cosmological implications of this primordial decay, quantifying the necessary conditions to achieve a successful mechanism for 'reheating’ the Universe into the SM. If there is enough time, I will also discuss the implications for primordial gravitational waves.

Boundary effects in entanglement entropy

Entanglement entropy is a useful tool which plays an important role in modern physics. The geometrical nature of entanglement entropy explains why it finds so many applications in various fields of physics, from black holes and holography to integrable models and quantum computers.

LABORATOIRE

ASTROPARTICULE & COSMOLOGIE

Théorie