Search for metastable heavy charged particles with large ionization energy loss in pp collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

Many extensions of the Standard Model predict the existence of massive charged long-lived particles, such as R-hadrons. These particles, if produced at the Large Hadron Collider (LHC), should be moving non-relativistically and therefore be identifiable through the measurement of an anomalously large specific energy loss in the ATLAS Pixel Detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex allows the investigation of the case where these are metastable with lifetimes in the nanosecond range. A search for such particles, produced in proton-proton collisions at $\sqrt{s}=13$ TeV at the LHC with the ATLAS detector, corresponding to an integrated luminosity of $3.2$ fb$^{-1}$, is presented in these proceedings. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on R-hadron production cross sections and masses are set. Gluino $R$-hadrons with lifetimes above 0.4 ns and decaying to $q\bar{q}$ plus a 100 GeV neutralino are excluded at the 95% confidence level, with lower mass limit ranging between 740 and 1590 GeV. In the case of stable R-hadrons the lower mass limit at the 95% confidence level is 1570 GeV.