Testes espectroscópicos de modificações da gravitação em átomos muônicos

Abstract

Several current models in Physics assume the existence of extra dimensions in order to solve certain theoretical challenges faced by the Standard Model, such as the hierarchy problem (the enormous difference in the intensity of the gravitational interaction compared to the magnitude of the other forces) and the search for a unification theory that includes gravity. In general, an important characteristic of extra-dimensional models is the prediction of amplification of the strength of the gravitational force at short distances. This peculiarity is of great interest from a phenomenological point of view because, in principle, it allows experimental examination of the existence of extra dimensions through laboratory tests of the inverse square law for the gravitational force. In this work, with the purpose of establishing experimental constraints for deviations of the gravitational interaction in subatomic domains, we will analyze recent spectroscopic data of muonic atoms. More specifically, we consider data on the 2P − 2S transition of muonic helium-4, muonic helium-3, muonic deuterium and muonic hydrogen. These atoms are produced in laboratories by replacing the electron with the muon. Since the mass of the muon is more than two hundred times greater than that of the electron, muonic atoms are suitable for probing modifications of gravitation in the atomic domain. We will compare our constraints with experimental limits previously determined from spectroscopic data of other atoms, such as electron hydrogen and antiproton helium. As we will see, our limits are the most stringent on the sub-picometer distance scale. We will also analyze the 2P3/2−2P1/2 transition of muonic helium-4, which depends on the fine structure of the atom. By studying the influence of the gravitational spin-orbit coupling on this transition, we will determine limits for deviations of the post-Newtonian potential associated with the gamma parameter of the Parameterized post-Newtonian formalism (PPN formalism).