## Research

### Publications

- Effective two-body approach to the hierarchical three-body problem: The motion of three bodies can be solved perturbatively when a tightly bound inner binary is orbited by a distant perturber. We construct an EFT to systematically implement this perturbative expansion, thus reducing the complexity of the three-body problem to a simpler spinning two-body motion. Our study builds towards a derivation of three-body analytic waveforms.
- On Perturbation Theory and Critical Exponents for Self-Similar Systems: We study the critical collapse of a complex scalar field enjoying a SL(2,R) symmetry. We numerically find the critical exponent characterizing the phase transition, and in particular we show that it can very when one changes the matter content, thus falsifying claims of universality of the critical exponent.
- Extreme Mass Ratio Inspirals with Scalar Hair: We introduce an effective field theory formalism designed to study gravitational wave generation in theories violating the so-called "no-hair theorem", in the extreme mass ratio case. This EFT will allow for a straightforward computation of waveforms at a high post-Newtonian order in a large class of theories deviating from GR, thus opening the door to modeled searches beyond General Relativity.
- Half-solution to the two-body problem in General Relativity: I introduce a resummation technique which allows to simplify the computations of Feynman diagrams involved in the effective field theory approach to the two-body problem. I introduce two new parameters which allow to define an effective two-body black hole horizon, then I generalize the notion of innermost circular orbit to the two-body problem.
- Unveiling the Galileon in a three-body system : scalar and gravitational wave production: We compute the Green's function of a cubic Galileon theory and derive the modifications to a gravitational wave signal of a very asymmetric inspiral (one or two "small" black holes of solar-size versus a gigantic black hole at the center of a galaxy).
- Two-body potential of Vainshtein screened theories: I investigate on two-body field configurations of scalar theories which incorporate a mechanism known as Vainshtein screening. Notably, I show for the first time that they induce a violation of the Weak Equivalence Principle and a modification of the orbit of the Moon, within the allowed range from observations.
- Disformally Coupled Scalar Fields and Inspiralling Trajectories: We show how a disformally coupled scalar field impacts the dynamics of inspiralling neutron stars or black holes.
- Effective field theory for gravitational radiation in scalar-tensor gravity: In this work, we adapted to a modified gravity setup the Effective Field Theory approach of Goldberger and Rothstein. This provides an alternative to the conventional Post-Newtonian framework in order to calcule the gravitational wave emitted by two inspiralling black holes or neutron stars, whose waveform is now recorded at the LIGO/Virgo detectors.
- Cross-correlation on CFHTLenS Galaxy Catalogue and Planck CMB Lensing: During this 6-month internship at Canada-France Hawaii Telescope, I studied the correlations beween a galaxy catalogue and the lensing map from Planck representing the deflection of the CMB photons by large-scale structures. I confirmed a bias in Planck data whose origin is not resolved yet

### Talks

#### Relativistic three-body problem

- 23 November 2021, Paris-Saclay AstroParticle Symposium 2021, online meeting and 13 December 2021, Théories Univers et Gravitation, Paris
- 12 October 2021, GdR Ondes Gravitationnelles, Annecy
- 08 October 2021, Laboratoire Univers et Particules de Montpellier and 14 October 2021, Laboratoire d'Annecy-le-Vieux de Physique Théorique
- 30 March 2021, 4th meeting of the national research group on gravitational waves, online meeting

#### PhD thesis presentation

#### Extreme mass ratio inspirals with scalar hair

#### The two-body problem in modified gravity

#### Gravitational waves

#### Two-body potential of Vainshtein screened theories

#### Effective field theory for gravitational radiation in scalar-tensor gravity, and disformally coupled scalar fields

### Miscellaneous

- Breakdown of Thermalization in Disordered Quantum Systems: Many Body Localization and its Consequences (3-month internship at CEA Saclay) : Report, Slides
- Cross-correlation on CFHTLenS Galaxy Catalogue and Planck CMB Lensing (6-month internship at Canada-France Hawaii Telescope) : Article, Slides
- Study of the hydrodynamical instabilities of the SWASI experiment (one-month internship at CEA Saclay ; in french) : Report, Slides (in French)
- International Physicists Tournament : my slides on the bounce of a rubber band ball.
- The coulosity of cheese : a very complete paper on the subject (in French)