Search for long-lived, massive particles in events with displaced vertices and multiple jets in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The collaboration
CERN-EP-2023-002, 2023.

Abstract (data abstract)
A search for long-lived particles decaying into hadrons ispresented. The analysis uses 139 fb$^{-1}$ of $pp$ collision datacollected at $\sqrt{s} = 13$ TeV by the ATLAS detector at the LHCusing events that contain multiple energetic jets and a displacedvertex. The search employs dedicated reconstruction techniques thatsignificantly increase the sensitivity to long-lived particlesdecaying in the ATLAS inner detector. Background estimates forStandard Model processes and instrumental effects are extracted fromdata. The observed event yields are compatible with those expectedfrom background processes. The results are used to set limits at95% confidence level on model-independent cross sections forprocesses beyond the Standard Model, and on scenarios withpair-production of supersymmetric particles with long-livedelectroweakinos that decay via a small $R$-parity-violatingcoupling. The pair-production of electroweakinos with masses below1.5 TeV are excluded for mean proper lifetimes in the range from0.03~ns to 1~ns. When produced in the decay of m(gluino)=2.4 TeVgluinos, electroweakinos with m(neutralino)=1.5 TeV are excludedwith lifetimes in the range of 0.02~ns to 4~ns.