It was only four years ago when the Higgs boson was discovered; after a search spanning nearly half a century, the Standard Model was complete.
The Higgs boson or, more accurately, the Higgs field gives fundamental subatomic particles their mass. Because of that, the Higgs boson preferentially interacts with heavier particles. Accordingly, LHC scientists probe their data, looking for something that points us toward a new theory that supersedes the Standard Model. As they probe higher and higher energies, it is expected that we might find new particles with even higher masses. And, since the Higgs boson interacts with massive particles, it seems reasonable that looking for a particle that decays into Higgs bosons might be a good way to look for something massive.
While there are some theories that predict the existence of a particle that decays into Higgs bosons, having a theory in hand is not necessary. It’s enough to look for the particular signature, and, if it is found, we can then figure out what it means.
Accordingly, CMS scientists went looking for events with these characteristics. Higgs bosons are unstable and preferentially decay into a bottom quark matter-antimatter pair. So what scientists were really looking for were events in which four bottom quarks were produced. When they found such an event, they used the energy and momentum of those four particles to see if they were consistent with making a pair of Higgs bosons.
No excess was found (and, to be honest, more data is needed to say anything definitive). However, scientists were able to look for hypothetical particles with a mass of about 25 times heavier than the Higgs boson and twice as heavy as was possible with previous measurements. Even though nothing unexpected was discovered, the approach is an interesting one, and scientists are exploring more recent data recorded at even higher energy in the hopes that this approach might lead to a new discovery.