Astroparticles and extra dimensions

by Argyris Nicolaidis (Aristotle University of Thessaloniki)

Thursday 26 Jun 2014, 11:00 → 12:00 Europe/Zurich

LAPTh, Auditorium

 In theories where gravity lives in 4+$\delta$ dimensions (with the extra $\delta$ dimensions compactified), gravity may become strong at an energy scale $M_f$  much lower than the Planck scale. For a such a scenario, we study interactions mediated by strong gravity and involving astroparticles. As an approximation we consider the particle scattering as taking place in an effective Schwarzchild geometry. Two distinct regimes appear. In the first regime the impact parameter $b$ is large and the scattering is similar to the traditional Rutherford-type scattering. In the second regime, $b$ is small and a singularity is developed. The singularity reflects the phenomenon of the particle orbiting around the black hole, before escaping to infinity. Another singularity, characteristic of the black hole presence, develops at backward scattering. We study also the photon axion mixing in the presence of extra dimensions and establish the resonance condition for the total conversion of a high energy photon into a Kaluza-Klein axion state. Similarly we consider the possibility of a flavor neutrino mixing with a sterile neutrino living in the bulk, leading to unconventional patterns of neutrino oscillations. We comment upon the possibility that the forthcoming experiments (searching for photons, axions, neutrinos) may give signals for extra dimensions.