A New Particle is Suggested by Anomalies Observed in Internal e \( ^+ \) e \( ^- \) Pair Creation

Several years ago, we detected unusual electron-positron angular correlations in the 18.15 MeV M1 transition of \(^8\) Be. We concluded that this was due to the formation and subsequent decay of an intermediate bosonic particle known as X17, which has a mass of 16.70 \(\pm 0.35 \) (stat) \(\pm 0.5\) (sys) MeV. This discovery sparked great interest in the physics community because of its potential connection to the dark matter issue. Furthermore, we observed similar anomalies in \(^4\) He, which may be explained by the production and decay of the same X17 particle. Recently, we used the \(^{11}\) B proton capture reaction to induce the 17.2 MeV broad ( \(\Gamma \) = 1.15 MeV) resonance in \(^{12}\) C and study the decay of their internal pairs. The electron-positron pairs exhibited anomalies in their angular correlation, which, combined with the data from \(^8\) Be and \(^4\) He, provides kinematic evidence for the existence of X17 and supports its explanation as a vector boson and fifth force.