RPC timing calibration and sensitivity study for heavy stable charged particles in ATLAS

The Standard Model (SM) of particle physics provides a remarkably successful description of elementary particles and their interactions, but several experimental and theoretical observations motivate the search for physics Beyond the Standard Model (BSM). Among the possible signatures of BSM models are Heavy Stable Charged Particles (HSCPs), such as long-lived staus in supersymmetric scenarios. Due to their large masses, they are expected to propagate through the detector with velocities significantly lower than those of relativistic SM particles. Their identification therefore relies critically on precise measurements of their time of flight (ToF). This thesis investigates the timing performance of the Resistive Plate Chambers (RPCs) in the ATLAS Muon Spectrometer (MS). The study focuses on the calibration of the RPC timing response and evaluates how its precision affects the measurement of the ToF and the subsequent reconstruction of the particle velocity. This impact is then assessed through a sensitivity study targeting supersymmetric staus with masses between 300 and 800 GeV. The results demonstrate that precise RPC timing calibration is essential for reliable velocity reconstruction, representing a crucial tool for enhancing the sensitivity of ATLAS searches for long-lived charged particles.