IN MY VIEW: Higgs boson: Now you see it, now you don't
Here’s the latest on the tantalizingly ephemeral Higgs boson. We’re talking about “The Missing Link, The God Particle, etc., etc.” and other significant labels used by the popular press.
By Jeffrey Bairstow
Here’s the latest on the tantalizingly ephemeral Higgs boson. We’re talking about “The Missing Link, The God Particle, etc., etc.” and other significant labels used by the popular press. You may not have seen the somewhat exuberant press releases generated by the recent Higgs boson seminar and broadcast around the world. So here are the more significant releases with some minor editing. (As of the first of this year, we have not yet seen any particles that could be classified as Higgs bosons—sigh. All italic comments are mine.)
At a seminar held last December at the huge CERN research center near Geneva, Switzerland—home of the Large Hadron Collider (LHC)—experimenters presented the status of their research for the Standard Model Higgs boson. (Editor’s note: There are two 3000-person teams working independently on the Higgs boson research with CERN’s LHC).
Their results are based on the analysis of considerably more data than presented at earlier conferences, sufficient to make significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or nonexistence of the elusive Higgs particle. (So why bother with this weak statement now?)
The main conclusion is that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 116–130 GeV by one experiment, and 115–127 GeV by a second experiment. Tantalizing hints have been seen by both experiments in this mass region, but these are not yet strong enough to claim a discovery.
Higgs bosons, if they exist, are very short lived and can decay in many different ways. Discovery relies on observing the particles they decay into rather than the Higgs itself. Both experiments have analyzed several decay channels, and the experiments see small excesses in the low mass region that has not yet been excluded.
Taken individually, none of these excesses is any more statistically significant than rolling a die and coming up with two sixes in a row. What is interesting is that there are multiple independent measurements pointing to the region of 124 to 126 GeV. It’s far too early to say whether the scientists have discovered the Higgs boson, but these updated results are generating a lot of interest in the particle physics community. (So why the premature half-assed discovery?)
Over the coming months, both experiment teams will be further refining their analyses in time for the winter particle physics conferences in March. However, a definitive statement on the existence or nonexistence of the Higgs will require more data, and is not likely until later in 2012.
The Standard Model is the theory that physicists use to describe the behavior of fundamental particles and the forces that act between them. It describes the ordinary matter from which we, and everything visible in the universe, are made extremely well. Nevertheless, the Standard Model does not describe the 96% of the universe that is invisible. One of the main goals of the LHC research program is to go beyond the Standard Model, and the Higgs boson could be the key. (Even then the Standard Model may not be the definitive answer to problems with particle physics.)
A Standard Model Higgs boson would confirm a theory first put forward in the 1960s, but there are other possible forms the Higgs boson could take, linked to theories that go beyond the Standard Model. A Standard Model Higgs could still point the way to new physics through subtleties in its behavior that would only emerge after studying a large number of Higgs particle displays.
A non-Standard Model Higgs, currently beyond the reach of the LHC experiments with data so far recorded, would immediately open the door to new physics, whereas the absence of a Standard Model Higgs would point strongly to new physics at the LHC’s full design energy capacity, set to be achieved after 2014. Whether ATLAS and CMS show over the coming months that the Standard Model Higgs boson exists or not, the LHC program is opening the way to new physics. (We’ll see about that!).
You may not have seen the somewhat exuberant press releases generated by the recent Higgs boson seminar and broadcast around the world.