We are still on the great cosmic scavenger hunt for dark matter, and the CMS experiment at CERN has been trying some delightfully weird detective work. Rather than only hunting for a single shiny new particle, we’re now also looking for spherical, fluffy clouds of low-energy particles — a signature called a Soft Unclustered Energy Pattern (SUEP) that might arise if a hidden “dark QCD” force exists in a dark sector parallel to our own. To help in the chase, members of the Particle Physics Collaboration (PPC) at MIT teamed up again with the Boston University team to dig deeper into this mystery using Higgs bosons produced alongside W or Z bosons as a clean trigger in the fog of collision noise. Their strategy cleverly exploits isotropy and track density to pick out the soft, spherical patterns from a background that usually looks, well… messy.
After combing the data with these tricks — and validating their background models against control samples — the result was classic physics suspense: no dramatic discovery just yet. But that’s not a flop — the team has set the most stringent limits so far on how often the Higgs could decay into these dark showers, improving previous bounds and providing useful, model-agnostic constraints that theorists can apply far and wide. Our work, in particular by graduate students Pietro Lugato and Luca Lavezzo, was just featured in a new CERN Courier article — “Soft clouds probe dark QCD” — which highlights the creativity and perseverance behind these hidden-sector searches. Check it out here.