Multiphoton signals of a (96 GeV?) stealth boson

Cascade decays of new scalars into final states with multiple photons and possibly quarks may lead to distinctive experimental signatures at high-energy colliders. Such signals are even more striking if the scalars are highly boosted, as when produced from the decay of amuch heavier resonance. We study this type of eventswithin the framework of the minimal stealth boson model, an anomaly-free U(1) Y extension of the Standard Model with two complex scalar singlets. It is shown that, while those signals may have cross sections that might render them observable with LHC Run 2 data, they have little experimental coverage. We also establish a connectionwith a CMSexcess observed in searches for new scalars decaying into diphoton final states near 96 GeV. In particular, we conclude that the predicted multiphoton signatures are compatible with such excess.