An Update on the Hypothetical X17 Particle

TL;DR

This paper reviews recent experimental evidence and ongoing research on the hypothetical X17 particle, a potential new boson suggested by anomalies in nuclear pair creation, including new findings from GDR decay studies.

Contribution

It provides an overview of existing experiments on X17 and presents new results from GDR decay analysis, advancing understanding of this hypothetical particle.

Findings

Observed anomalies in e$^+$e$^-$ pair correlations suggest possible X17 particle signals.

Reviewed multiple experiments supporting the existence of X17.

New GDR decay data offers additional insights into X17 properties.

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.