Prepare the fireworks: The discovery of the Higgs boson is finally here. Early in the morning on July 4, physicists with the Large Hadron Collider at CERN announced they have found a new particle that behaves similarly to what is expected from the Higgs.
“As a layman, I would now say, I think we have it,” said CERN director-general Rolf-Dieter Heuer. “It’s a historic milestone today. I think we can all be proud, all be happy.” Both CMS and ATLAS, the two main LHC Higgs-hunting experiments, are reporting a boson that has Higgs-like properties at a mass of 125 gigaelectronvolts (GeV) with a 5-sigma significance, meaning they are 99.999 percent confident of its existence.
At the first mention of 5-sigma by physicist Joe Incandela, who presented results from one of the main Higgs-searching efforts at the LHC, the audience burst into applause. “It was really a magnificent moment to see the reaction from the community,” he said later in a question and answer session. “Emotionally it didn’t really hit me until today because we have had to be so focused, and so much work to do.”
Though CERN scientists are making sure to be cautious about over-interpreting their data, the results are impressive and historic, and today will likely go down as the day the Higgs discovery was announced.
“This boson is a very profound thing that we have found. This is not like other ordinary particles,” Incandela said. “We are reaching into the fabric of the universe like we’ve never done before. It’s a key to the structure of the universe.”
First hypothesized in the 1960s, the Higgs boson is the final piece of the Standard Model, the physics framework explaining the interactions of all known subatomic particles and forces. The Higgs has been the subject of an extensive two-decade search, first at the European Large Electron-Positron Collider, then the Tevatron at Fermilab in Illinois, and finally at the LHC. Finding the Higgs within the predicted energy range is a major vindication for the Standard Model.
“I never expected this to happen in my lifetime and shall be asking my family to put some champagne in the fridge,” physicist Peter Higgs, the particle’s namesake who first theorized the existence of the particle, said in a statement.
The Higgs is certainly the most important discovery in the field for a generation. The last of the Standard Model’s 16 particles to be found was the top quark, discovered at Fermilab’s Tevatron in 1995, while many physicists would point to the detection of the W and Z boson in 1983 as the field’s most recent monumental finding. And considering that it is gives rise to the mass of all other particles, the Higgs may well be the most important new particle found for years to come.
Discovering the Higgs boson is not likely to radically change life for most people — it will not lead to better communications devices or fancy new electronics. But knowing its characteristics will bring physicists a better understanding of nature. The Higgs is important because it is the manifestation of the Higgs field, which is thought to permeate all of space and interact with all other subatomic particles. This interaction leads to the different mass for each elementary particle. Some particles, like protons, are slowed by this field, like a tennis ball going through molasses, and are relatively heavy while others, like electrons, shoot rapidly through like BB gun pellets, making them light.
To search for the Higgs, the LHC has been smashing together protons at incredibly high speeds, counting out the many elementary particles created from these energetic slams. Heavy particles, like the Higgs boson, almost immediately decay into simpler fragments.
What physicists have been searching for are characteristic decays that indicate the existence of the Higgs. Since the process is somewhat chaotic, it takes a long time to sift through the results and determine which decays are indicating which particles.
That’s why particle physicists use statistics to interpret their results, proving that a small excess of certain decays is not just a coincidence. In December, the LHC had collected enough data to ascertain that some events were pointing to the creation of Higgs particles at 125 (GeV) with a 3-sigma significance, meaning they had a 0.13 percent chance of happening by chance. What they have been waiting for is the stringently high bar of a 5-sigma result, which has only a one in 3 million chance of happening randomly.
Head to Wired for the rest of this landmark story.