Flavio Mercati Abstract

Flavio Mercati

Title: Probing the quantum-gravity realm with cold particles

Abstract: The regime in which gravitational and quantum phenomena should become both important, namely the "quantum gravity" regime, was traditionally assumed to be that of ultra-high energies/ultra-short wavelengths (theoretical arguments favored energies of the order of 10^28 eV, the "Planck Scale"). Recently, some theoretical indications were found that pointed toward the opposite, low energy/long wavelengths regime as another place where we could, at least in principle, expect new physics coming out of quantum gravity. I show that atom interferometry experiments are capable of putting strong constraints on a class of effects (namely, deformations of the dispersion relation), which, despite being regulated by the Planck scale, have the property of becoming more noticeable when the energies of the particle become smaller. The limits that can be put with the current data are already near the Planck scale. I also show a class of models, which arose in a context connected to string theory, in which a very similar deformation of the dispersion relation totally decouples from the Planck scale, due to a singular phenomenon known as "Infrared-Ultra Violet mixing". I conclude announcing an amusing anomaly, which we found looking for precise tests of de Broglie relation, which was formerly unnoticed. This anomaly, which seems to have a 4-standard-deviations significance, is found in an experiment with ultra cold neutrons, and could be explained by the models with "Infrared-Ultra Violet mixing".