Stau pairs from natural SUSY at high luminosity LHC

Abstract

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 τ˜1 of a few hundred GeV, the decays τ˜1→τχ˜1,20 and ντχ˜1− occur at comparable rates where the (Higgsino-like) χ˜1± and χ˜20 release only small visible energy: in this case, the expected τ+τ−+ET signature is diminished from the usual expectations due to the presence of the nearly invisible decay mode τ˜1→ντχ˜1−. However, once mτ˜1≳m(bino), decays to binos such as τ˜1→τχ˜30 open up where χ˜30 decays to Higgsinos plus W±, Z0, and h at comparable rates. For these heavier staus, the stau pair production gives rise to diboson+ET events, which may contain 0, 1, or 2 additional hard τ 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 5σ HL-LHC discovery reach for 3000  fb−1, we do find a 95% CL exclusion reach, ranging between mτ˜1:  100–450  GeV for mχ˜10∼100  GeV. This latter reach disappears for mχ˜10≳200  GeV. Published by the American Physical Society 2024