Prospect for a search for direct stau production in events with at least two hadronic taus and missing transverse momentum at theHigh Luminosity LHC with the ATLAS Detector

Only one scenario of combined $\tilde{\tau_{L}}\tilde{\tau_{L}}$ and $\tilde{\tau_{R}}\tilde{\tau_{R}}$ production is excluded for the current searches at LHC, where the $\tilde{\tau_{R}}$ mass is 109 GeV and the $\tilde\chi^0_1$ is massless. The reach at the high-luminosity phase of the LHC is expected to significantly extend beyond the current limits. This document presents example benchmark studies for direct stau production in events with at least two hadronic taus and missing transverse momentum with a parameterized simulation of the ATLAS detector at a centre-of-mass energy of 14 TeV. Results are shown for an integrated luminosity of 3000$\,$fb$^{-1}$. For a massless $\tilde\chi^0_1$, the 5$\sigma$ discovery sensitivity reaches up to 100 (120) to 500 (430) GeV in $\tilde{\tau}$ mass for the combined $\tilde{\tau_{L}}\tilde{\tau_{L}}$ and $\tilde{\tau_{R}}\tilde{\tau_{R}}$ (pure $\tilde{\tau_{L}}\tilde{\tau_{L}}$) production, and the 95\,\% CL exclusion contour reaches 700 GeV in $\tilde{\tau}$ mass for the combined $\tilde{\tau_{L}}\tilde{\tau_{L}}$ and $\tilde{\tau_{R}}\tilde{\tau_{R}}$ production, 650 (540) GeV for pure $\tilde{\tau_{L}}\tilde{\tau_{L}}$ ($\tilde{\tau_{R}}\tilde{\tau_{R}}$) production with massless $\tilde\chi^0_1$.