Théorie

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 

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.

Infrared effects in de Sitter spacetime: nonperturbative treatment of secular terms

The study of interacting quantum fields in de Sitter geometry reveals
peculiarities that are of conceptual and phenomenological interest. In
this geometry, the exponential expansion of the metric produces an
effective growth in the self-interaction of light fields, breaking down
the standard perturbative expansion. Furthermore, in the massless limit
the free propagators do not respect the symmetries of the classical
theory, and neither do they decay at large distances.

Emergent gravity in graphene and in Dirac/Weyl semimetals

In graphene in the presence of strain the elasticity theory metric naturally appears. However, this is not the one experienced by fermionic quasiparticles. Fermions propagate in curved space, whose metric is defined by expansion of the effective Hamiltonian near the topologically protected Fermi point. We calculate the corresponding emergent gravitational fields. Next, we extend our consideration to the case, when the dislocations are present.

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