Search for a Resonance Decaying Into a Scalar Particle and a Higgs Boson in the Final State With Two Bottom Quarks and Two Photons in Proton-Proton Collisions at √<i>s</I>=13 Tev With the Atlas Detector

Abstract

A search for the resonant production of a heavy scalar X decaying into a Higgs boson and a new lighter scalar S, through the process X -> S(-> b (b) over bar )H(->gamma gamma), where the two photons are consistent with the Higgs boson decay, is performed. The search is conducted using an integrated luminosity of 140 fb(-1) of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The search is performed over the mass range 170 <= m(X) <= 1000 GeV and 15 <= m(S) <= 500 GeV. Parameterised neural networks are used to enhance the signal purity and to achieve continuous sensitivity in a domain of the (m(X), m(S)) plane. No significant excess above the expected background is found and 95% CL upper limits are set on the cross section times branching ratio, ranging from 39 fb to 0.09 fb. The largest deviation from the background-only expectation occurs for (m(X), m(S)) = (575, 200) GeV with a local (global) significance of 3.5 (2.0) standard deviations.