Search for long-lived charginos based on a disappearing-track signature in pp collisions at √s=13 TeV with the ATLAS detector

This paper presents a search for direct electroweak gauginoor gluino pair productionwith a charginonearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb−1 of pp collisions at s √ =13 s=13 TeV collected by the ATLAS experimentat the LHC. The final state of interest is a disappearing track accompanied by at least one jet with high transverse momentum from initial-state radiation or by four jets from the gluino decay chain. The use of short track segments reconstructed from the innermost tracking layers significantly improves the sensitivity to short charginolifetimes. The results are found to be consistent with Standard Model predictions. Exclusion limits are set at 95% confidence level on the mass of charginosand gluinosfor different charginolifetimes. For a pure wino with a lifetime of about 0.2 ns, charginomasses up to 460 GeV are excluded. For the strong production channel, gluinomasses up to 1.65 TeV are excluded assuming a charginomass of 460 GeV and lifetime of 0.2 ns.