|Physicists are on a mission to find the Higgs boson, the missing piece of the standard model.|
Variations on the headline, “Fermilab scientists search for the God particle” are common in today’s media. “God particle,” an inaccurate pseudonym for the Higgs boson taken from Leon Lederman’s eponymous book, is certainly attention-grabbing. However, readers should raise an eyebrow at the use of such a simple word as “search,” which totally understates the magnitude of the effort involved in looking for the Higgs boson.
To begin with, the process begins with large and complex particle detectors and accelerators. Each one takes many hundreds of skilled people to design, build and operate. Next, a veritable army of physicists must convert the raw bits and bytes into the electrons, muons, photons and jets that others can sift through. They are looking for the signature of Higgs bosons.
Once the raw data has been translated into physical objects, the fun really starts. We don’t know if the Higgs boson exists at all, but if it does, the theory makes firm predictions as to how it decays. A heavy Higgs boson would preferentially decay into pairs of W bosons, while lighter Higgs bosons would decay into pairs of bottom quarks.
One problem with searching for something that might not exist is that we don’t know its mass. We must look for all possible decays of Higgs bosons, of which there are many more than could be listed here. Also, there are collisions leading to pairs of bottom quarks, frequently from processes that don’t involve Higgs bosons. Accordingly, we search for collisions in which the Higgs boson is created in association with other particles. This improves the possibility that any particular Higgs boson candidate collision might actually contain a Higgs boson.
Finally, because of the extremely rare possibility of manufacturing a Higgs boson, both DZero’s and CDF’s data sets must be combined. This leads to another level of complexity, since the data sets can only be compared and combined if we know the similarities and differences of the two detectors in extreme detail.
On July 27, Fermilab scientists announced at an international conference a measurement that combined many distinct analyses in the search for the Higgs boson. The particle was not observed, but the Tevatron data continues to broaden the range of masses that are excluded. We are 95 percent certain that the mass of the Higgs boson will not be in the range of about 156–177 GeV/c2. This analysis utilizes about 70 percent of the data we expect to collect by the end of Run II in September. The remaining data and anticipated improvements in analysis techniques will allow the Tevatron Higgs search to remain competitive in the near future.
Learn more about the Higgs boson with this video.