Search for decays of the Higgs boson into scalar particles decaying into four or six b quarks using pp collisions at √s = 13 TeV with the ATLAS detector

Abstract

A search for exotic decays of the Higgs boson H into new scalar or pseudoscalar particles thatsubsequently decay into b-quarks is presented. The search considers ZH production with several decayscenarios for the Higgs boson; first to a pair of identical scalars, H RIGHTWARDS ARROW 2a RIGHTWARDS ARROW 4b, second to a pair of scalarswith different masses (ma1 < ma2), either directly, H RIGHTWARDS ARROW a1a2 RIGHTWARDS ARROW 4b, or via a longer decay chain,H RIGHTWARDS ARROW a1a2 RIGHTWARDS ARROW 3a1 RIGHTWARDS ARROW 6b. The analysis uses proton-proton collision data atffiffiffisp1/4 13 TeV collected withthe ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb-1.No significant excess above the Standard Model prediction is observed. The search sets upperlimits at 95% confidence level on the ratio of the Higgs boson production cross section to the SMprediction times the branching ratio of Higgs bosons decaying into 4b or 6b, between 4% and25% for σðZHÞ=σSMðZHÞ x BðH RIGHTWARDS ARROW 2a RIGHTWARDS ARROW 4bÞ, between 24% and 38% for σðZHÞ=σSMðZHÞ xBðH RIGHTWARDS ARROW a1a2 RIGHTWARDS ARROW 4bÞ, and between 10% and 20% for σðZHÞ=σSMðZHÞ x BðH RIGHTWARDS ARROW a1a2 RIGHTWARDS ARROW 3a1 RIGHTWARDS ARROW 6bÞ,depending on the masses of the scalar particles.