Search for decays of the Higgs boson into scalar particles decaying into four or six 𝑏 quarks using 𝑝𝑝 collisions at $\sqrt{𝑠}$ = 13 TeV with the ATLAS detector
A search for exotic decays of the Higgs boson 𝐻 into new scalar or pseudoscalar particles that subsequently decay into 𝑏-quarks is presented. The search considers 𝑍𝐻 production with several decay scenarios for the Higgs boson; first to a pair of identical scalars, 𝐻 → 2𝑎 → 4𝑏, second to a pair of scalars with different masses (𝑚 𝑎1 < 𝑚 𝑎2 ), either directly, 𝐻 → 𝑎 1 𝑎 2 → 4𝑏, or via a longer decay chain, 𝐻 → 𝑎 1 𝑎 2 → 3𝑎 1 → 6𝑏. The analysis uses proton-proton collision data at $\sqrt{𝑠}$ = 13 TeV collected with the 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 upper limits at 95% confidence level on the ratio of the Higgs boson production cross section to the SM prediction times the branching ratio of Higgs bosons decaying into 4𝑏 or 6𝑏, between 4% and 25% for 𝜎(𝑍𝐻)/𝜎 SM (𝑍𝐻) × ℬ(𝐻→ 2𝑎→ 4𝑏), between 24% and 38% for 𝜎(𝑍𝐻)/𝜎 SM (𝑍𝐻) × ℬ(𝐻 → 𝑎 1 𝑎 2 → 4𝑏), and between 10% and 20% for 𝜎(𝑍𝐻)/𝜎 SM (𝑍𝐻) × ℬ(𝐻→𝑎 1 𝑎 2 → 3𝑎 1 → 6𝑏), depending on the masses of the scalar particles.