An analysis of the omega meson conversion decay using neural network-based technique with the CMD-3 experiment

Abstract

The study of the conversion decay of the omega meson into π 0 e + e − state was performed with the CMD-3 detector at the VEPP-2000 electron-positron collider in Novosibirsk. The main physical background to the process under study is radiative decay ω → π 0 γ, where monochromatic photon converts to e + e − on the material in front of the detector. The deep neural network was used to suppress these background events. The neural network was trained based on Monte Carlo simulation. To control the systematic uncertainty of this approach the events of the process of inelastic scattering e + e − → e + e − γ (eeγ) and events of annihilation into two photons (γγ) were used since they are similar to signal and background events under study. The cross-sections of these processes are well calculated based on quantum electrodynamics. The difference in the calculated and measured ratio of the number of events Neeγ /Nγγ was used to determine a systematic uncertainty. Using integrated luminosity about 10 pb -1 collected at the c.m. energy range from 775 MeV to 800 MeV the visible cross-section of the process ω → π 0 e + e − was measured. The preliminary result for the branching ratio Br(ω → π 0 e + e −) was obtained.