Séminaire

Speed of Gravity and Cosmology Constraints from Binary Neutron Stars using Time Delays between Gravitational Waves and Short Gamma-ray Bursts

The landmark detection of a gravitational wave (GW) from the Binary Neutron Star Merger (BNS) GW170817 and its electromagnetic counterparts allowed us to study the Universe in an entirely new way. Among the several discoveries made possible by GW170817, we can find the tightest constraints on the speed of gravity and the measurement of the Hubble constant (H0). Both of these measurements were made thanks to several assumptions and conditions that might not hold for future detections.

How to unravel early moments of the Universe with neutrinos: introduction to the PTOLEMY project

What would we give to see an even younger image of the Universe from relics of the Big Bang?  And how can one even imagine how to do that?  One of the most subtle and important discoveries in elementary particle physics was to find that the tiny neutral particles that Enrico Fermi called the neutrinos have mass.  This mass was discovered indirectly through an effect predicted by Bruno Pontecorvo, now probed to high precision by KM3Net.

Neutrino-Nucelus Interaction Physics in 1-10 GeV

Precise nuclear physics theories and models are playing an increasingly important role in neutrino physics. While this has long been recognized in low-energy neutrino experiments, recent advances in accelerator-based neutrino oscillation studies have further highlighted the importance of nuclear many-body effects. Modern experiments such as T2K and NOvA require accurate simulations of nucleon correlations, a necessity that will persist in future experiments like ORCA and IceCube-Upgrade, DUNE, and Hyper-Kamiokande.

Backreaction and Cosmic Butterflies: what simulations can tell us about inflation

The small-scale physics of inflation can leave unique observational signatures in the gravitational wave background and may also generate primordial black holes as a dark matter candidate. These phenomena often involve a significant enhancement of inflationary fluctuations, potentially leading to the breakdown of standard perturbation theory. In this talk, I will discuss how lattice simulations provide a crucial tool for addressing these challenges.

Effective field theory reproducing the MOND phenomenology based on a non-Abelian Yang-Mills graviphoton

Motivated by the phenomenology of MOND, we propose a theory based on a fundamental non Abelian Yang-Mills gauge field with gravitational coupling constant (a "graviphoton") emerging in a regime of weak acceleration, i.e. below the MOND acceleration scale. Using the formalism of the effective field theory and invoking a mechanism of gravitational polarization of the dark matter medium, we show that generic solutions of this theory reproduce the deep MOND limit without having to introduce in an ad hoc way an arbitrary function in the action.

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