'Interesting' Higgs Boson Result to be Announced
It may not be the long-awaited news about a Higgs boson discovery, but an “interesting” announcement will soon come from scientists analyzing data from the Tevatron particle accelerator at Fermilab, near Batavia, Ill.
Wait a minute, isn’t the Tevatron in semi-retirement? Yes and no.
Although its house-sized particle detectors have seen their last high-energy collisions, huge quantities of Tevatron data have yet to be analyzed.
According to Rob Roser, lead researcher of the Tevatron’s CDF experiment, there’s something hiding in the data that could support recent findings to come from the Tevatron’s European successor, CERN’s Large Hadron Collider (LHC). What’s more, the announcement will be made public next month.
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Speaking at the American Association for the Advancement of Science (AAAS) conference in Vancouver on Friday, Roser said: “We will be able to say something interesting, though whether it is that we don’t see it or we do see it remains to be seen.”
So what is Rosen referring to?
Long after the Tevatron powered down, physicists still had their work cut out. Many billions of particle interactions had been recorded by the CDF detector and stored for later analysis. By sifting through these data after the fact, a signal has started to reveal itself.
The signal appears to be growing at around the 125 gigaelectron volt range — within a range of energy that LHC scientists are also seeing a “bump” in their datasets. This just happens to be one of the predicted energies that the Higgs boson may have.
However, this signal is just a hint; not a discovery, yet. Roser has said that the March announcement will hinge on a “three-sigma” event. This is physics talk for the certainty that the signal is real. A “three-sigma” signal means there is still a 0.1 percent chance that the signal is noise or some statistical anomaly.
The statistical likelihood of the LHC signal being “real” stands at an unofficial 4.3 sigma (from the combined results gathered from the ATLAS and CMS detectors) — meaning there is a 99.996 percent chance the signal is real (and a 0.004 percent chance it’s noise).
So both the LHC and Tevatron results still have to go through some analysis and more collisions need to be recorded before a much-needed “five-sigma” signal — the “gold standard,” or one in a million chance that the result isn’t real — is achieved.
2012 promises to be a very exciting year for particle physicists. In this epic game of searching for a very small needle in a very big haystack, physicists at Fermilab raced to find hints of the Higgs before the LHC could even get warmed up.
But since 2010, the European accelerator has performed flawlessly, outclassing the Tevatron in energy and sophistication. However, the older Tevatron (that was commissioned in 1987) had the advantage of many years of experience and data collection up until decommissioning in September 2011.
Ultimately, it all comes down to raw energy, and the maximum energy available to the Tevatron was 1 teraelectron volt (hence its name) — the LHC is designed to accelerate particles at seven times the Tevatron’s best.
So, as physicists at Fermilab pour over years of data, and physicists at CERN continue to ramp up collision energies, the quantum haystack is rapidly shrinking for the Higgs boson. It’s only a matter of time before the Higgs is either discovered or disproven. (But my money is on the former, and before the end of this year.)
Image: CDF Central Outer Tracker chamber being installed in the Central Detector in 2000. Credit: Reidar Hahn/Fermilab.