Scientists have finally discovered the Higgs boson—or have they?
This week we’ll see a number of announcements concerning the Higgs boson. These announcements could declare that the elusive particle has been found or is nonexistent. The scientific community will welcome the news either way, since the result (whatever it may be) would represent a major advance in our understanding of the universe.
It’s easy to take the precise cosmological measurements for granted, like the universe being 13.75 +/- 0.11 billion years old and comprised of 4.56 +/- 0.16 percent of normal atoms. Yet I can remember, in February 2003, waiting anxiously for a seminar that would reveal the first results from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite—during a time when scientists were far less certain of these cosmological parameters. Many scientists (myself included) expected the WMAP results to confirm the inflationary big bang model (with cold dark matter and dark energy), but, based on what I sensed from others in the room, some have hoped the results would disprove the model. A similar tension exists today as eager scientists head into a week of announcements concerning the Higgs boson.
Here is a list of how to stay updated with the expected announcements:
- On July 2, Fermilab will share the latest results from its data and analysis. Since the Tevatron ceased operations over a year ago, the news from Fermilab will probably only give hints at a possible Higgs detection.
- On July 4, CERN will update a December 13, 2011 news release about the Higgs boson indicating “signs of its existence.” The addition of this year’s data to the “signs” from last year led many interested parties to expect a discovery announcement.
- On July 7, during the ICHEP in Australia, talks relevant to the Higgs boson search will be webcast live.
- On July 9, the combined results of two LHC detectors, capable of detecting the Higgs, CMS, and ATLAS, will be part of plenary sessions delivered at the ICHEP (and webcast live). Even if the detectors do not achieve (individually) the required signal to declare detection, the combined signal from both should.
This coming week should resolve what the instruments reveal so far.
If the Higgs boson is proven to exist, it would complete the zoo of fundamental particles in the standard model of particle physics. The zoo contains three classes of particles. First, six quarks (up, down, charm, strange, bottom, and top) make up the more familiar proton and neutron (and a host of other, more exotic particles). Second, there are three leptons (the electron, muon, and tauon) and their corresponding neutrinos. Lastly, four kinds of bosons are the particles that mediate the electromagnetic, strong and weak nuclear forces.
Although scientists know lots about the zoo, they can’t explain the masses of various particles unless something like a Higgs boson exists. If it does, this means that a Higgs “field” pervades space, and all the other particles gain mass by interacting with this field. Detecting the Higgs would cap a fifty-year search for understanding particles mass.
But what if the Higgs doesn’t exist?
The main motivation for building the LHC was to detect the Higgs boson. A non-detection would tell us that the Higgs doesn’t exist and that the current explanation for understanding mass is wrong. Though this might seem like a bad thing, it isn’t.
Ultimately, scientists want to know how all of the four fundamental forces unify under one common theoretical umbrella. The standard model of particle physics provides that umbrella for the electromagnetic, strong nuclear and weak nuclear interactions. General relativity provides the best explanation for gravity but is fundamentally incompatible with the standard model. Also, the existence of dark matter and dark energy require physics beyond the standard model. A nonexistent Higgs (or even detecting a Higgs that doesn’t match the one required by the standard model) would provide important clues to the model that brings gravity, dark matter, and dark energy under the umbrella. For example, the results of the Higgs search could reveal that supersymmetry models, which predict an expanded zoo of particles (and naturally explain dark matter), are correct.
I fully expect the announcement of a Higgs-like particle sometime this week. I also realize that further research remains in order to verify that such a particle has all the properties required by the standard model. And if it does, one must wonder whether the Higgs will reveal any fine-tuning required to make a universe capable of supporting life. Based on past experience, I would bet on it.