Search for a resonance decaying into a scalar particle and a Higgs boson in the final state with two bottom quarks and two photons with 199 fb⁻¹ of data collected at √ = 13 TeV and √ = 13.6 TeV with the ATLAS detector

A search for the resonant production of a heavy scalar decaying into a Higgs boson and a lighter scalar , through the process → (→ ¯)(→ ), where the two photons are consistent with the Higgs boson decay, is performed. The search is conducted using integrated luminosities of 140 fb⁻¹ and 58.6 fb⁻¹ of proton–proton collision data at centre-of-mass energies of 13 TeV and 13.6 TeV respectively, recorded with the ATLAS detector at the Large Hadron Collider. The search is performed over the mass ranges of 170 ≤  ≤ 1000 GeV and 15 ≤  ≤ 500 GeV. No significant excess over the Standard Model background prediction is observed and limits at 95% confidence level are set on the cross-section times branching ratio ( → (→ ¯)(→ )) at 13 TeV, ranging from 9 fb to 0.06 fb.