Searching for light dark matter with the PADME experiment

Abstract

The search for dark matter at accelerators has gained a lot of attention in recent years. Among the theoretical scenarios that can be studied, an attractive one is postulating a new $U_D(1)$ gauge symmetry mediated by a massive boson often named dark photon $A'$. The $A'$ could be the bridge between the Standard Model (SM) and a hypothetical Dark Sector (DM), having a small coupling $\epsilon$ with SM particles. PADME (Positron Annihilation to Dark Matter Experiment) is the first fixed target experiment searching for the $A'$ produced in association with a photon in $e^+e^-$ annihilations. It exploits the missing mass technique and does not make any assumption on the decay mode of the $A'$. PADME is located at the Laboratori Nazionali di Frascati (LNF) of INFN and it is designed to be sensitive to the production of a dark photon with mass $M_{A'} \le 23.7 \ \rm{MeV}$. Its setup is also ideal to investigate other scenarios of low mass dark matter: axion-like particles (ALPs), dark Higgs, and the $X_{17}$ boson claimed to explain anomalies observed recently in a nuclear physics experiment.