Evaporating Kerr black holes as probes of new physics

A bstract We focus on inferring the particle content of the underlying theory of particle physics using Primordial Black Holes (PBHs). Namely, knowing the mass and spin of a PBH at different times, we are able to estimate the number of accessible particle degrees of freedom characterizing the related temperature. The method relies on a non-negligible spin of the PBH. One can be agnostic on the mechanism leading a PBH to have a non-negligible spin today. Nonetheless, we considered the scenario provided by the axiverse in which a remnant of a PBH would have a non-extremal spin and therefore we consider the values of the spin motivated by such scenario (0 ≤ ã ≤ 0 . 6). We also propose a method to determine the spin of PBHs based on the simultaneous measurement of energies of the first peaks in the primary photon and neutrino Hawking spectrum. This method is suitable for primordial black holes of very different masses. Nonetheless, it is of drastic interest in the case of a black hole exceeding the temperature tested in colliders. In fact, relying only on primary emissions, this method does not depend on the coupling between the standard model particles and whatever may hide beyond.