Scientists believe they have found “the God particle”

Scientists cite evidence of the Higgs boson

Posted: Wednesday, Jul. 04, 2012

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Primer on the Higgs boson

What is it and what does it do?

School physics teaches that everything is made up of atoms, and inside atoms are electrons, protons and neutrons. They, in turn, are made of quarks and other subatomic particles. Scientists have long puzzled over how these minute building blocks of the universe acquire mass. Without mass, particles wouldn’t hold together and there would be no matter.

Scientists have theorized that the Higgs boson gives each type of particle its own mass. British physicist Peter Higgs proposed what we now call the Higgs field, and hypothesized that it spreads through the universe. All particles would acquire mass by interacting with this field. As is the case with the other interactions, at a quantum level, this Higgs interaction predicts that we should be able to produce and detect the boson associated with it, or the Higgs boson.

Why it this important?

The Higgs boson is part of many theoretical equations underpinning scientists’ understanding of how the world came into being. If it doesn’t exist, then those theories would need to be fundamentally overhauled. The fact that it apparently does exist means scientists have been on the right track with their theories. But there’s a twist: The measurements seem to diverge slightly from what would be expected under the so-called Standard Model of particle physics. This is exciting for scientists because it opens the possibility to potential new discoveries including a theory known as “super-symmetry” where particles don’t just come in pairs – think matter and antimatter – but quadruplets, all with slightly different characteristics.

How do you find it?

The Large Hadron Collider at the CERN laboratory in Geneva collides protons together. Very occasionally, a Higgs boson would be produced in these collisions. However, there are many other collisions that are very similar to those that produce Higgs bosons but are not. They are considered as “background” events, and they have to be quantified. When one sees a significant excess of “Higgs- like” events above the expected backgrounds can one claim evidence for the existence of a Higgs boson.

How much did it cost?

The collider costs some $10 billion to build and run. This includes the salaries of thousands of scientists and support staff around the world who collaborated on the two experiments that independently pursued the Higgs.

Are there any practical results from the search?

Not directly. But the scientific effort that led up to the discovery has paid off in other ways, one of which was the creation of the World Wide Web. CERN scientists developed it to make it easier to exchange information among each other. The vast computing power needed to crunch all of the data produced has also boosted the development of distributed – or cloud – computing, which is now making its way into mainstream services. Advances in solar energy capture, medical imaging and proton therapy – used in the fight against cancer – have also resulted from the work of particle physicists at CERN and elsewhere.

What’s next?

Scientists will keep probing the new particle until they fully understand how it works. In doing so they hope to understand the 96 percent of the universe that remains hidden from view. This may result in the discovery of new particles and even hitherto unknown forces of nature.

Associated Press and Bloomberg News

DURHAM The audience could have been at a rock concert, applause erupting with each new song.

Scientists at CERN, the organization that runs the Large Hadron Collider may have found the elusive Higgs boson, nicknamed “the God particle.” It is the last blank to fill in the Standard Model of subatomic particles and could be critical to understanding exactly how the universe was created.

The applause wasn’t for songs, but for slides in two PowerPoint presentations that aired Wednesday at 3 a.m. Eastern Daylight Time from Geneva. The crowd cheered whenever they saw “5 sigma” on a slide, meaning there is less than a one-in-a-million chance the results are a fluke.

It is the end of an almost 50-year investigation, with thousands of scientists involved.

The results may have little technical importance now, but Al Goshaw, professor of physics at Duke, said it’s a bit like space exploration.

“We’re trying to understand nature at its most fundamental level,” he said. “These theories also connect to the beginning of the universe. To know how that happened, we need this basic science.”

The Standard Model in particle physics is somewhat like the periodic table in chemistry; basically a spreadsheet of particles. A particle’s location predicts its properties. Some particles in the Standard Model are quarks, which are the building blocks of protons and neutrons.

It will take years of further experimentation to test whether this new particle truly is the Higgs. If it is, then the Standard Model gets a stamp of approval, and our theories about subatomic particles have been on the right track.

“But it could be something entirely new,” Goshaw said.

This possibility is as tantalizing as the Higgs to some scientists. This would open up a whole new field of discoveries, and would require an overhaul of the Standard Model.

One thing is indisputable.

“We have certainly discovered a new particle,” Goshaw said.

Goshaw worked on the ATLAS detector, one of the two detectors at LHC looking for the Higgs. CMS is the other. The two projects presented their results independently on Wednesday, and the results both told the same story.

“It behaves exactly like the Higgs boson is predicted to behave,” Goshaw said.

The Higgs boson is a force-carrying particle. Each of the four fundamental forces of nature is proposed to have such a particle.

One of these forces is the electromagnetic force. When two charged objects are brought close together, they interact by sending photons, also known as light particles, to each other.

When two heavy objects like the Earth and moon are brought close to each other, they interact with the gravitational force. The Higgs boson, if theories are correct, is the particle that transmits this force. The Higgs is to gravity as the photon is to the electromagnetic force.

It was difficult to look for the Higgs because gravity, believe it or not, is the weakest of the four forces. Atom-smashing events that produce this particle are extremely rare.

Further, because the Higgs is a heavy particle, more than 100 times the mass of a proton, it requires enormous energies. Only the LHC could provide the oomph needed, and it has only been open for business since 2008.

The LHC has almost 17 miles of tunnels to accelerate particles through before colliding them. The detectors then record the aftermath, the particle debris from the collision. The physicists, like ballistics experts, then deduce what happened at the scene of the crime.

Goshaw underscores the importance of the competition between ATLAS and CMS in producing these results.

“The two drive each other. We eat lunch together, but we’re really quite competitive. We don’t share,” he says. “There’s often a husband on one team, a wife on another. Who knows if they have anything to talk about at dinner?” he said, chuckling.

On the other hand, Goshaw has been proud to see such an international collaboration.

“It’s like a United Nations of Science, just working well together,” he said.

This basic science of such discoveries also has beneficial spinoffs.

“It really captures the imaginations of students,” says Goshaw. Fifteen Duke students are at CERN this summer. “They get this strong technical training, but most go off and do other things. We’re really producing talented people.”

Some of those talented people may take Goshaw’s “Standard Model” course at Duke next year.

“Every year, my last transparency says ‘A key component’ is still missing,” he says. “It will be a pleasure to have a happy ending next time.”