The Higgs boson: one might not be enough

A popular extension of the Standard Model includes the principle of supersymmetry. This extension is called the minimal supersymmetric Standard Model (MSSM) and it predicts not one, but five Higgs bosons, including some with electric charge. This analysis searched for the three electrically neutral Higgs bosons predicted by the MSSM, shown here in red.

Fermilab Today readers have heard a lot about the search for the Higgs boson. What might be surprising is that scientists don’t know if it exists. We don’t know if there is only one Higgs boson or many or even none. What physicists do know, however, is that the Standard Model predicts a single Higgs boson with specific properties. These predicted properties are that the Higgs boson is massive, electrically neutral and is not made of smaller particles.

On the other hand, we also know that the Standard Model is incomplete. We know this because we cannot answer many key questions about the universe with the information we have. Scientists have proposed extensions to the Standard Model as one potential way to help answer these questions. One such extension is to include a new principle called supersymmetry.

There are many ways to add supersymmetry to our currently successful theories, but the simplest and least intrusive version is called the MSSM, for minimal supersymmetric Standard Model. This extension of the existing theory offers potential answers to those unanswered questions. However, when we look at the MSSM to understand its consequence to Higgs theory, we find that this new theory predicts not one Higgs boson, but five, including two electrically charged Higgs bosons.

CMS physicists searched for the three neutral MSSM Higgs bosons by looking for their decays into pairs of tau leptons. While this particular decay path is relatively rare, it is uncommon to produce pairs of tau leptons using more ordinary physics. This makes it easier to ferret out these hypothetical MSSM Higgs bosons.

Unfortunately, no evidence for this trio of MSSM Higgs bosons was observed, but physicists were able to rule out a much bigger range of values for the theoretical parameters than had been achieved by earlier measurements. This is just the start of the story as CMS scientists will continue to pursue this analysis as the data rapidly accumulates.

— Don Lincoln

These physicists contributed to this analysis.
Because the LHC can deliver collisions far more rapidly than they can be recorded, the CMS detector selects only a fraction of them. These physicists from the University of Wisconsin-Madison have played a strong role in developing and maintaining the electronics and algorithms that use calorimeter data to select interesting events.