Public talks are scheduled to discuss the latest results from ATLAS and CMS, two of the main LHC experiments, on Dec. 13. This follows one day after a closed-door CERN council meeting where officials will get a short preview of the findings, whatever they may be.
“Chances are high (but not strictly 100%) that the talks will either announce a (de facto or de iure) discovery or some far-reaching exclusion that will be really qualitative and unexpected,” wrote theoretical physicist Lubos Motl on his blog.
Motl also mentioned that an internal email sent to the CERN community suggests that results on the elusive Higgs — which is required under the Standard Model of particle physics to provide mass to different particles — will be inconclusive. This could mean that the finding is below the five-sigma threshold needed to definitively declare a discovery in physics.
Physicists are often quoted as saying that finding no Higgs boson would be more exciting than finding one. Steven Weinberg, who shared the Nobel prize for physics in 1979, once told me that finding the Standard Model Higgs boson would not rescue physics but send it into the doldrums. I quoted him in Massive, saying: "It would be just what we're expecting and it would give us no clue to anything new. Finding several kinds of Higgs, or even no Higgs at all, would be better."
There are popular theories that demand the existence of a bunch of Higgs bosons. Some versions of supersymmetry (Susy), an idea that says every kind of particle has an invisible twin, call for five Higgs bosons, all with different masses. A Susy Higgs boson might look very similar to a Standard Model Higgs at the LHC, because it decays into the same variety of lighter particles. But the Susy version might give a weaker signal, and so take more time to find.
If the LHC scientists say definitively that there is no Higgs boson, it would be bad news for supersymmetry. As Ellis puts it: "If they don't find a Standard Model Higgs I would begin to worry seriously about supersymmetry because in popular models a Susy Higgs should appear in a similar way to a Standard Model Higgs."
Beyond supersymmetry, there are alternative theories that replace the Higgs with other ways to give mass to fundamental particles. The Higgs boson is simply the quantum, or signature particle, of the postulated Higgs field, and it is the field that really matters.
According to Peter Higgs and the five other physicists who came up with the theory in 1964, the Higgs field is what separated the electromagnetic force from the weak force (which goes to work in certain nuclear reactions, including those that make the sun shine) when the universe was young. It did this by making the particles that carry the weak force (the W and Z bosons) heavy, while leaving particles of light (the quanta of the electromagnetic field) massless. It isn't a huge leap to envisage the field giving mass to other basic particles, like electrons and quarks.
The alternatives to the Higgs theory are exciting because whatever form they take, they break new ground in physics. Some call for a new force of nature, others for extra dimensions, but these are only two of the options. I hope to write about them in more detail next week.
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