An Update on the Hypothetical X17 Particle

Abstract

Recently, when examining the differential internal pair creation coefficients of ${}^8$Be, ${}^4$He and ${}^{12}$C nuclei, we observed peak-like anomalies in the angular correlation of the e${}^{+}$e${}^{-}$ pairs. This was interpreted as the creation and immediate decay of an intermediate bosonic particle with a mass of $m_X{c}^2\approx$ 17~MeV, receiving the name X17 in subsequent publications. Our results initiated a significant number of new experiments all over the world to detect the X17 particle and determine its properties. In this paper we will give an overview of the experiments the results of which are already published, and the ones closest to being published. We will also introduce our latest results obtained for the X17 particle by investigating the e${}^{+}$e${}^{-}$ pair correlations in the decay of the Giant Dipole Resonance (GDR) of ${}^8$Be.

18 pages, 6 figures, ISMD 2023 Conference, Gyöngyös, Hungary