Speaker
Description
While the discovery of the Higgs boson completed the Standard Model (SM), several fundamental questions remain unresolved, including the hierarchy problem and the nature of dark matter. Many well-motivated extensions of the SM introduce additional scalar bosons through an extended Higgs sector, providing rich phenomenology accessible at the LHC.
A powerful strategy to probe such models is the search for cascade decays of heavy scalar resonances to lighter resonances. In this talk, we present a search for an asymmetric cascade decay in which a heavy scalar boson, $X$, decays into a lighter scalar boson, $S$, and a SM-like Higgs boson, $H$, with both subsequently decaying to bottom-quark pairs ($X \rightarrow SH \rightarrow b\bar{b}b\bar{b}$).
The analysis uses the Run 2 dataset collected by the ATLAS detector. The four-bottom-quark final state offers strong sensitivity thanks to the large $H \rightarrow b\bar{b}$ branching ratio and state-of-the-art jet reconstruction and flavour tagging techniques, including algorithms optimised for boosted topologies. These developments allow us to probe a wide mass range for both $X$ and $S$, significantly extending the experimental reach for new scalar states predicted by extended Higgs sector models.