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'God particle' likely discovered

Scientists working at the world's biggest atom smasher in Switzerland say they have discovered what could be the long-sought Higgs boson, a subatomic particle dubbed the "God particle" because it is believed to have originated during the Big Bang and helped shape the subatomic particles that make up all matter in the universe.

Rolf Heuer, director of the European Centre for Nuclear Research (CERN) in Meyrin, Switzerland, near the border with France, made the announcement early Wednesday, saying that researchers "have now found the missing cornerstone of particle physics."

He described the discovery as a boson, a wider class of subatomic particle, but stopped short of confirming that it's a Higgs boson — an extremely fine distinction.

"As a layman, I think we did it," he said. "We have observed a new particle that is consistent with a Higgs boson."

The Higgs boson has been labelled the "God particle" in the mainstream media because of the fundamental questions it could answer about matter and the creation of the universe, and although most physicists avoid using the term they do agree that the Higgs boson plays a key role in what is known as the Standard Model of physics, which describes the particles from which everything in the universe is made and how they interact.

The Standard Model includes common subatomic particles like electrons and protons along with less familiar ones like muons.

The Higgs boson is the only one that remains undetected in experiments and is extremely important because it is believed to impart mass to particles.

The existence of a Higgs boson was first proposed by British physicist Peter Higgs and his colleagues at Edinburgh University in 1964 as a way of explaining how particles gained mass, a property that at first did not seem to fit into the Standard Model of how electrons and protons interact.

Higgs proposed that particles gain mass by interacting with a medium that exists everywhere in space and is made up of unseen particles called bosons.

Higgs's theory does not assign a specific mass to the boson itself but gives a range of values for the potential masses it could have, and it was these values that gave CERN scientists a way to detect traces of the particle.

The scientists did not spot the particle per se but detected its footprint when observing high-speed collisions of other subatomic particles in two separate experiments conducted with the ATLAS and CMS particle-collision detectors, which detect collisions within CERN'sLarge Hadron Collider.

They had a range of values for what the likely mass of the boson is and by knowing the masses of the particles they could detect in the accelerator and analysing the collisions, they were able to detect the likely presence of the boson.

The scientists said both particle accelerators detected "strong indications for the presence of a new particle, which could be the Higgs boson, in the mass region around 126 gigaelectronvolts."

Wednesday's announcement follows decades of work and billions of dollars spent on a project that has involved scientists in dozens of countries.

To mark the occasion in Canada, a few dozen physicists and other experts at TRIUMF, a particle physics lab in Vancouver that has been involved with the hunt for the Higgs boson, gathered overnight to celebrate.

"It's a big day for CERN, a big day for international science, and a big day for science in Canada," said Oliver Stelzer-Chilton, a physicist at the TRIUMF lab.

"But now, we have to come to the bottom of it," he said. "What is nature telling us that this new particle is?"

"At this point, we can say it's consistent with the properties that we expect from a Higgs boson, but we basically have to measure those properties to be sure."

Physicists working at the Large Hadron Collider had already found what they believe were hints pointing to the existence of the Higgs boson, but until now, it has remained a theoretical particle.

The ATLAS and CMS teams have been gathering data and running separate but parallel experiments over the course of 2011 and 2012 in hopes of glimpsing the Higgs boson for the first time.

The ATLAS collaboration includes researchers from around the world, including Canada, who have been working to analyze the vast amounts of scientific data generated at CERN.

One-tenth of the data generated by the ATLAS experiment is sent to the TRIUMF supercomputer in Vancouver, where it is then analyzed by experts at a few Canadian universities.

On Wednesday, the leaders of the two CERN teams — Joe Incandela, head of CMS, with 2,100 scientists, and Fabiola Gianotti, head of ATLAS, with 3,000 scientists — each presented what was essentially extremely strong evidence of a new particle.

The announcement was timed to coincide with the first day of the International Conference on High Energy Physics in Melbourne.

The researchers stressed that the results are preliminary and that a full analysis of the data they gathered over 2011 and 2012 won't be published until the end of July.

"Positive identification of the new particle's characteristics will take considerable time and data," the CERN statement said. "But whatever form the Higgs particle takes, our knowledge of the fundamental structure of matter is about to take a major step forward."

CERN described the particle as a possible "bridge to understanding the 96 per cent of our universe that remains obscure," a reference to the fact that the matter that we can see represents only about four per cent of all matter in the universe.