Yet again, the Higgs boson dominates news headlines around the world. At time of writing, it was even a "trending topic" on Twitter, competing with Lady Gaga and Santa.
This time it's not rumors; it's not reports about the hypothetical superpowers of the mysterious subatomic particle; it's a bona fide announcement by physicists at the European Organization for Nuclear Research (CERN).
Although Tuesday's news fresh from the Large Hadron Collider's (LHC) supercooled magnets isn't confirmation about a Higgs boson discovery, it is an indication that this is the closest we've come in the search for the mysterious particle.
And the endgame is nearing.
The existence of the Higgs particle will either be confirmed or denied by the LHC in the next few months. 2012 will be the year when the final piece of the Standard Model puzzle slots into place. No more rumors, no more "tentative glimpses"; 2012 will answer the big question: Does the Higgs boson exist?
ANALYSIS: What Is The Higgs Boson?
"Given the outstanding performance of the LHC this year, we will not need to wait long for enough data and can look forward to resolving this puzzle in 2012," said Guido Tonelli, spokesman for the Compact Muon Solenoid (CMS) experiment, at Tuesday's seminar discussing this most recent twist in the high-energy physics soap opera.
Fabiola Gianotti, lead scientist for the ATLAS experiment, urged some caution, pointing out that although it's looking promising these new results may indicate something entirely different. "I think it would be extremely kind of the Higgs boson to be here," she said during the seminar. "But it is too early."
"More studies and more data are needed. The next few months will be very exciting ... I don't know what the conclusions will be."
"Bumps" and Freight Train Collisions
So, what's the reason for physicists getting all hot and heavy over the Higgs?
Well, there's a small "bump" in the data generated by two humongous detectors situated around the LHC's 17 mile (27 kilometer) loop of subterranean electromagnets straddling the France-Swiss boarder near Geneva.
Inside the CMS and ATLAS detectors, gazillions of protons are slammed head-on at relativistic speeds (i.e. close to the speed of light). The bigger the particle accelerator (like the LHC), the faster the protons; the more focused the beams, the bigger the energies produced in the collisions.
ANALYSIS: Flurry of New Results Narrow Range for Higgs
After the protons collide, a whole host of "new" particles condense from the huge quantities of energy being flung around. The conditions are so extreme that, for the briefest of moments, energies that haven't been seen since the Big Bang are possible (hence why the LHC is sometimes called "The Big Bang Machine"). Therefore, primordial particles that wouldn't normally exist by themselves in our modern Universe are suddenly possible.
For want of a better analogy, it's a bit like two freight trains colliding. Out of the resulting fire and carnage, dozens of cars spontaneously form, spraying out from the wreckage.
In this fantasy collision, the trains are the protons, and the cars could represent post-collision particles detected in ATLAS and CMS, most of which are common and expected to be created (Fords, Chevvys, Hondas). Some of these particles "decay" rapidly into other particles, others survive, penetrating deep into the LHC's detectors.
WIDE ANGLE: BIG QUESTIONS FOR 2012
However, a very small number are not predicted and are considered "exotic" (a Ferrari here, a Lamborghini there). Suddenly, we're very interested in the exotic cars.
It's these exotic, primordial free particles (cars) that may show up as "bumps" in the LHC's detectors.
What's in a "Bump"?
The ATLAS and CMS detectors have both discovered "excesses" in particle counts after countless particle collisions. Here's a funky graph from the ATLAS experiment:
This plot basically shows the energy of detected particles along the bottom (x-axis) and "confidence level" (CL) up the side (y-axis). The dotted, curved line (inside the green band), is the energy of the particles that would theoretically be detected if the Higgs boson doesn't exist.
However, the dark wavy line represents the particles that the ATLAS detector has actually detected so far. As you can see, this line differs greatly from the theoretical line -- the bump skyrockets at around the 125 GeV (Giga-electronvolts), approximately 125-times the mass-energy of a single proton -- breaking the green barrier (representing "1-sigma") and the yellow barrier (representing "2-sigma"). In fact, this peak represents a "2.4 sigma" result.
This refers to the statistical certainty of a given result. A 3-sigma event has a 99.73002 percent chance of being correct (and a 0.26998 percent chance of being wrong). "Three-sigma isn't seen as a 'discovery,'" Jon Butterworth, LHC physicist working with the ATLAS detector, said in a previous Discovery News article. "Really, a 'five-sigma' is classed as a discovery. Five-sigma is the 'Gold Standard.'" A 5-sigma event has a 99.99994 percent chance of being correct (and only a 0.00006 percent chance of being wrong).
"Ah ha!" say physicists when they see this, "something 'exotic' is going on."
The 2.4-sigma result represents a 98 percent certainty that this bump is real and not experimental error. What's more, the bump lies right around the predicted energy of a "light" Higgs boson as predicted by the Standard Model -- the theory that governs all known particles and forces (except gravity).
A 98 percent certainty is promising, but it's not a discovery. LHC physicists will be getting excited about this, but until these excesses (or "bumps") in the data reach the "5-sigma" threshold -- when the certainty becomes 99.99994 percent, or one-in-a-million chance that it's wrong -- the Champagne corks will remain plugged inside their bottles.
What Now?
Basically, more data is needed.
It's a bit like exposing an old photographic plate to a very dim light. Cover the plate up quickly, and only a small number of photons from the light source has hit it. A very dim, fuzzy and low-definition image is the result.
However, leave the photographic plate uncovered for longer, and more photons from the light source will hit the plate, making the resulting photograph brighter, clearer and more defined.
This is exactly what the LHC detectors need: more time to collect more particle detections, making any "bumps" in the data more prominent and more certain. However, there is a small chance that with more collisions, this particular bump in the ATLAS and CMS data is an artifact, error or just noise, and will start to fade from view.
But the fact that two detectors have independently spotted a faint signal, around about the predicted range (115-130 GeV) that theorists expected to find a Higgs boson... to a certainty of 1.9 sigma (for the CMS result) and 2.4 sigma (for the ATLAS result), it's hard not to get excited.
The next few months will be crucial for the Higgs boson hunt, and it's looking like 2012 will be the year for the LHC.
MORE BIG QUESTIONS FOR 2012:
Was There Ever Life on Mars?
Is the Polar Bear Doomed?
The Great Pyramid's Secret Doors
Image: The LHC's huge ATLAS experiment. Credit: CERN/LHC
Tags: Laboratories, Large Hadron Collider, Particle Physics, Particles, Physics
comments ( )