Search for heavy long-lived multi-charged particles in the full Run-II $pp$ collision data at $\sqrt{s}$ = 13 TeV using the ATLAS detector

A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data collected in 2015–2018 at $\sqrt{s}$ =13 TeV from $pp$ collisions corresponding to an integrated luminosity of 139 fb$^{−1}$ are examined. Particles producing anomalously high ionisation, consistent with long-lived massive particles with electric charges from |q|=2e to |q|=7e are searched for. No statistically significant evidence of the sought particles is observed, and 95% confidence level cross-section upper limits are calculated and interpreted as the lower mass limits for a Drell–Yan plus photon fusion production mode. The mass limits range between 1050 GeV for |q|=2e and 1600 GeV for |q|=6e.