Stau pairs from natural SUSY at high luminosity LHC

Natural supersymmetry (SUSY) with light Higgsinos is perhaps the most plausible of all weak scale SUSY models while a variety of motivations point to (right) tau sleptons as the lightest of all the sleptons. We examine a SUSY model line with rather light right staus embedded within natural SUSY. For light (tau) over tilde (1) of a few hundred GeV, the decays (tau) over tilde (1) -> tau(chi) over tilde (0)(1,2) and nu(tau)(chi) over tilde (-)(1) occur at comparable rates where the (Higgsino-like) (chi) over tilde (+/-)(1) and (chi) over tilde (0)(2) release only small visible energy: in this case, the expected tau(+)tau(-) = is not an element of(T) signature is diminished from the usual expectations due to the presence of the nearly invisible decay mode (tau) over tilde (1) -> nu(tau)(chi) over tilde (-)(1). However, once m((tau) over tilde1) greater than or similar to m(bino), decays to binos such as (tau) over tilde (1) -> tau(chi) over tilde (0)(3) open up where (chi) over tilde (0)(3) decays to Higgsinos plus W-+/-, Z(0), and h at comparable rates. For these heavier staus, the stau pair production gives rise to diboson +is not an element of(T) events, which may contain 0, 1, or 2 additional hard t leptons. From these considerations, we examine the potential for future discovery of tau-slepton pair production at a high-luminosity LHC. While we do not find a 5s HL-LHC discovery reach for 3000 fb(-1), we do find a 95% CL exclusion reach, ranging between m((tau) over tilde1) : 100- 450 GeV for m((chi) over tilde 10) similar to 100 GeV. This latter reach disappears for m((chi) over tilde 10) greater than or similar to 200 GeV.