Searching for heavy, charged, long-lived particles via ionization energy loss and time-of-flight in the ATLAS detector using $140$ fb$^{-1}$ of $\sqrt{\mathrm{s}}$ = $13$ TeV proton-proton collision data

Many extensions to the Standard Model predict the existence of new, massive, long-lived particles. Such heavy particles produced in proton-proton collisions at center-of-mass energy $\sqrt{\mathrm{s}}$ = $13$ TeV are expected to move significantly slower than the speed of light as they traverse a detector. As a charged particle passes through a material, the amount of energy it loses via ionization is related to its speed. This property can be used to identify slow-moving particles. A heavy, charged, long-lived particle should be identifiable in a detector as a trajectory with high momentum and anomalously large ionization energy loss. The first search for heavy, charged particles using ionization energy loss in the full ATLAS Run $2$ dataset observed an excess with a global significance of $3.3$$\sigma$ at high mass. We discuss these results and present a followup search for slow-moving particles in $140$ fb$^{-1}$ of ATLAS Run $2$ data. This new search expands the analysis strategy by incorporating a second measure of particle speed, time-of-flight measurements, to significantly reduce background and improve sensitivity to heavy, charged, long-lived particles. Results are interpreted in terms of supersymmetric models that predict long-lived gluinos, charginos, and sleptons.