|The latest combined results from CDF and DZero test whether the newly observed particle measures up to the expectations of a Standard Model Higgs boson.|
If the new particle discovered in July is the long-sought Higgs boson, then it should measure up like one when compared to the predictions of the Standard Model. The Higgs boson plays an important role in the Standard Model, giving mass to the quarks, charged leptons and weak-force carriers, but the Standard Model version of the Higgs boson is not the only possible way to explain why those particles are massive. Many exotic theories exist beyond the Standard Model that predict one or more versions of a Higgs boson that would behave differently from Standard Model expectations. The latest combination of CDF and DZero results seeks to measure the behavior of the newly observed boson to help determine whether it could be the Standard Model Higgs boson or is possibly something more exotic.
The Higgs boson can be produced in many ways during a proton-antiproton collision, and once one is made it can decay in many ways as well. Exotic models might turn off certain production and decay modes while enhancing others. Measuring the Higgs boson production rate in each independent decay channel allows the predictions of the Standard Model and these exotic models to be tested. At the Tevatron, the rates for Higgs boson decays to W boson pairs, tau lepton pairs and bottom quark pairs were all consistent with the Standard Model. More photon pairs were observed in the combined search than were predicted by the Standard Model by a slight margin, but not enough to be incompatible with it.
The combined analysis goes a step further by simultaneously examining the new boson’s particle characteristics during production and decay. Many analysis channels contain a mixture of processes, perhaps with quarks being involved in producing a Higgs boson and W bosons involved in its decay. Tracking all of these possible combinations individually allows the CDF and DZero collaborations to constrain the fundamental preferences the new boson has between bosons and other particles. These results are all consistent with the Standard Model prediction for a Higgs boson.