DZero data supports spinless Higgs particle

The Higgs boson and its decay products would have different event characteristics if its intrinsic spin were not the value of zero predicted by the Standard Model.

While studies so far have shown that the particle discovered by the LHC experiments in 2012 is some version of a Higgs boson that appears consistent with the Standard Model, there’s a chance that a look from a different angle will put a new spin on things. To be consistent with the predictions of the Standard Model, the Higgs boson must have the correct fundamental properties. Each elementary particle has an inherent property known as spin, which quantifies the intrinsic angular momentum it carries. In the Standard Model, the Higgs boson is the only elementary particle with zero spin. A recent analysis at DZero tests the Standard Model against an alternate possibility for a Higgs boson that assumes the particle has spin two.

A particle’s spin affects its interactions with other particles. A Higgs boson with a non-zero spin value would be produced and decay in a different manner than the Standard Model predicts and lead to different event characteristics in the DZero detector. To test for these differences, three teams of analyzers re-examined the data used in the most sensitive searches at DZero for the Higgs boson decaying into two bottom quarks. Each team used the differences in the expected features of Higgs events to separate between a spin zero Higgs boson and a particular model where the Higgs boson has a spin value of two.

When combined, the three analyses rule out the spin two Higgs boson model tested with 99.9 percent confidence. This result complements other measurements of Higgs boson spin because it is the first with sensitivity to Higgs boson decays to bottom quarks.

The analyzers also considered the possibility that a pair of Higgs bosons exist, one each of spin zero and spin two, and placed a constraint on the contribution of the spin two portion to the total signal. The analyzers are actively working on testing other spin hypotheses in an effort to capitalize on the DZero experiment’s sensitivity to Higgs boson decays to bottom quarks.

Mike Cooke

These physicists made major contributions to this analysis.
The DZero Authorship Committee, chaired by Alan Jonckheere (Fermilab), actively maintains the evolving list of hundreds of author names that appear at the beginning of every paper DZero publishes.