Search for the X17 particle in ${}^7\mathrm{Li}(\mathrm{p},{\mathrm{e}}^{+}{\mathrm{e}}^{-}{)}^8\mathrm{Be}$ processes with the MEG II detector

The MEG II collaboration, K. Afanaciev, A. M. Baldini +64

The observation of a resonance structure in the opening angle of the electron-positron pairs in the ${}^7$Li(p,\ee) ${}^8$Be reaction was claimed and interpreted as the production…