Search for phenomena beyond the Standard Model in events with large $b$-jet multiplicity using the ATLAS detector at the LHC

Abstract

A search is presented for new phenomena in events characterised by high jet multiplicity, no leptons (electrons or muons), and four or more jets originating from the fragmentation of $b$-quarks ($b$-jets). The search uses 139 fb${}^{-1}$ of $\sqrt{s}$ = 13 TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider during Run 2. The dominant Standard Model background originates from multijet production and is estimated using a data-driven technique based on an extrapolation from events with low $b$-jet multiplicity to the high $b$-jet multiplicities used in the search. No significant excess over the Standard Model expectation is observed and 95% confidence-level limits that constrain simplified models of R-parity-violating supersymmetry are determined. The exclusion limits reach 950 GeV in top-squark mass in the models considered.

40 pages in total, author list starting page 24, 8 figures, 6 tables, submitted to Eur. Phys. J. C. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2018-38/

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• Search for top squark production in fully-hadronic final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for R-parity violating supersymmetry in a final state containing leptons and many jets with the ATLAS experiment using $\sqrt{s}=13$ TeV proton-proton collision data
• Status of searches for electroweak-scale supersymmetry after LHC Run 2
• Improving sensitivity of trilinear RPV SUSY searches using machine learning at the LHC
• Magnetic shielding for large photoelectron multipliers for the OSIRIS facility of the JUNO detector
• Estimation of the chances to find new phenomena at the LHC in a model-agnostic combinatorial analysis