The study of the X17 anomaly with the PADME experiment

Abstract

In dark matter studies, the absence of experimental evidences other than the astrophysical observations, has triggered new approaches. Nowadays, many particle physics experiments at accelerators are trying to contribute by looking for signals of hidden particles postulated by different theoretical extensions of the Standard Model. This results in a vaste hunting for new particles with a wide range of properties with the intention to also give reason to other unexplained particle physics phenomena. Within this scenario is inserted the Positron Annihilation into Dark Matter Experiment (PADME) ongoing at the Laboratori Nazionali di Frascati of INFN that is looking for signals of hidden particles by studying the annihilations of a positron beam with the electrons of a fixed target. PADME had, up to now, two data taking periods devoted to the search of a dark photon signal, but its setup turned out to be also suited to explore the existence of a protophobic new boson of mass 17 MeV/c 2 postulated to explain an anomalous effect observed by a Hungarian group while studying nuclear excited states. In this paper it is reported an overview of the PADME experiment and of the modifications implemented to allow a dedicated data taking at 282 MeV beam energy, meant to produce the new particle at resonance.