Théorie

Discussion of the paper 

Love numbers beyond GR from the modified Teukolsky equation
Pablo A. Cano
https://arxiv.org/pdf/2502.20185

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.

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.

In recent years, Scattering Amplitudes methods, developed for computations in relativistic Quantum Field Theories, have been applied to compute observables which are relevant for the generation of Gravitational Wave templates. In the first part of the talk, I will give a review of recent achievements. In the second part of the talk, I will talk about new attempts to compute gravitational waveforms directly from Amplitudes, their matching to classical results from General Relativity and ongoing developments.

Abstract: Blazars are among the most powerful objects in the Universe. These active galactic nuclei launch a relativistic jet that is viewed under a small inclination angle from Earth. They are characterized by a high time variability along the whole electromagnetic spectrum, reaching from scales of minutes to years. Is the time period between such blazar flares declining, then they can be caused by jet precession in an inspiraling supermassive binary black hole at the blazar center.
 

 We show that the minimal Weyl-invariant Einstein-Cartan gravity in combination with the Standard Model of particle physics contains just one extra scalar degree of freedom (in addition to the graviton and the Standard Model fields) with the properties of an axion-like particle which can solve the strong CP-problem. The smallness of this particle's mass as well as of the cosmological constant is ensured by tiny values of the gauge coupling constants of the local Lorentz group.

Neutrino-neutrino scatterings create entanglements between them which may affect their flavor evolution. Although insignificant in terrestrial settings, this phenomenon may be consequential in some astrophysical environments where neutrinos transport significant amount of energy and lepton number including core collapse supernova and neutron star mergers. The problem is equivalent to that of a many-body system away from equilibrium and presents significant challenges.

To be announced.