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Particle Discovery Brings Scientists Close to Understanding Mass

July 04, 2012

Particle Discovery Brings Scientists Close to Understanding Mass

A graphic showing a collision of particles at the Compact Muon Solenoid experience, at CERN, in Geneva, on December 13, 2011. Photographer: Fabrice Coffrini/AFP/Getty Images

Scientists seeking to explain the origins of matter discovered a particle that may support a decades-old theory of physics, bringing people closer to understanding unseen parts of the universe.

The observed particle is the heaviest boson ever found, said Joe Incandela, spokesman for one of the experiments at CERN, the European Organization for Nuclear Research, at a seminar yesterday at its Geneva headquarters. Scientists stopped short of claiming they have found the elusive Higgs boson, a theoretical particle that could explain where mass comes from.

“As a layman, I think I would say ‘we have it,’” said Rolf-Dieter Heuer, director of CERN, at a press conference in Geneva. It will take at least three to four years of research to fully understand the properties of the observed particle, Heuer said.

The announcement brings humankind closer to answering a millennia-old question that the ancient Greeks wrestled with: what is matter made of? The particle is a key to the Standard Model, a theory explaining how the universe is built, and its existence would help scientists gain a better understanding of how galaxies hold together. It also could open a door to exploring other parts of physics such as superparticles or dark matter that telescopes can’t detect.

‘Sings and Dances’

The new boson “sings and dances like” the theoretical particle, said Pauline Gagnon, a researcher on the Atlas set of experiments in Geneva, in an interview in Melbourne, where she was attending the bi-annual International Conference on High Energy Physics. “There is no doubt it comes from a different signal, different channels, with different experiments. We just need in the next few months with more data to ascertain exactly what are the properties of this particle to see if it is exactly the Standard Model Higgs boson or some variation of it."”

Particle physics is the study of the elemental building blocks that make up matter. These particles, with names such as quark, fermion, lepton and boson, can’t be subdivided. They exist and interact within several unseen ‘‘fields’’ that permeate the universe.

The field that generates mass for objects is named for U.K. physicist Peter Higgs, who in the 1960s was one of the first scientists to outline a working theory on how elemental particles achieve mass. Higgs was one of four of the theorists attending yesterday’s meeting in Geneva. He wiped a tear from his eye as the findings were presented.

Champagne for Higgs

‘‘For me, it’s really an incredible thing that it’s happened in my lifetime,” Higgs said in Geneva. In a statement, he said he would be “asking my family to put some champagne in the fridge.”

Higgs wrote that some particles -- such as photons, the basic unit of light -- don’t interact with the Higgs field, and thus don’t achieve mass. Most others do.

To put it another way, if the Higgs field were a Hollywood party, a photon would be the unknown actor who hurries through without gaining a bit of interest from others in the room. Other particles would be more like Angelina Jolie, drawing crowds of hangers-on as they move through the party.

It gets increasingly harder to stop such a cluster from moving forward and more difficult to get it moving again once it’s stopped, meeting one definition of mass.

Scientists are trying to prove the existence of the Higgs field by displaying a physical effect for the Higgs boson, a particle that lives for less than a trillionth of a second and is an excitation, or force, within the Higgs field.

Digging Deeper

Providing indirect evidence that the Higgs field exists will allow scientists to dig even deeper into the secrets of our existence, said Mark Wise, a professor of physics at California Institute of Technology.

“In some sense, this is the beginning,” Wise said of finding the boson. “Because we want to know all its properties.”

The data presented yesterday are the latest from the $10.5 billion Large Hadron Collider, a 27-kilometer (17-mile) circumference particle accelerator buried on the border of France and Switzerland. CERN has 10,000 scientists working on the project, in which billions of subatomic particles are hurled at each other at velocities approaching the speed of light.

The collider will provide more data later this year, giving scientists a more complete picture of the observed new particle. Researchers will try to determine whether it is a Higgs boson, the particle predicted by the Standard Model.

Like Columbus

“Very few physicists would privately argue that this is not a Higgs particle,” said Themis Bowcock, head of particle physics at the University of Liverpool, in a statement. “For physicists, this is the equivalent of Columbus discovering America.”

A more exotic version of the Higgs particle could help scientists understand the 96 percent of the universe that remains obscure, since observable matter only represents 4 percent of the total, CERN said.

To declare the boson is discovered, physicists use the statistical standard of “five sigma,” meaning that there should only be a 1 in 3.4 million chance that a sighting would be due to chance. The observations of the new particle have a five-sigma level of significance, Incandela said.

“The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks,” he said.

To contact the reporters on this story: Thomas Mulier in Geneva at tmulier@bloomberg.net; Jason Gale in Singapore at j.gale@bloomberg.net

To contact the editor responsible for this story: Phil Serafino at pserafino@bloomberg.net


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