Speaker
Description
Extensions of the Standard Model often feature heavy, charged, long-lived particles. These particles are expected to move significantly slower than the speed of light as they traverse the detector. The identification of such slow-moving charged particles can be made using measurements of ionization energy loss along a track. Specific ionization energy loss (dE/dx), converted into $\beta\gamma$ via the Bethe-Bloch relation when $\beta\gamma < 1$, can be used to determine particle mass for a given momentum. This analysis searches for massive, charged, long-lived particles beyond the Standard Model using a measurement of dE/dx from the ATLAS silicon pixel detector. An additional measurement of $\beta\gamma$ from the time-of-flight in the ATLAS tile calorimeter provides an independent mass measurement and is used to confirm that the particles are slow-moving. In this poster we present limits on the pair-production of massive, charged BSM particles???such as R-hadrons and staus???over a broad range of lifetimes using the full Run 2 data set of 140 fb$^-1$ from the ATLAS experiment. Improved limits on the pair-production of charginos with lifetimes > 1 ns are presented for the first time.
