Author’s Note: For the scientific community, the most significant event in July is undoubtedly the discovery of the Higgs boson’s traces at the LHC. BoJone has selected an article from the New Scientist website to translate, so that everyone can understand some of the details. Of course, the discovery of this Higgs boson already happened on July 4th, so this post is quite late. The reason for the delay was a malfunction of the Universe Station... Better late than never. I am posting it now to share with everyone. The translation may be imperfect; please point out any errors. Experts, please excuse my efforts ^_^
Celebrating the Final Discovery of the Higgs Boson!
Author: Celeste Biever, CERN, Geneva July 4, 2012
Although there is still a five-in-ten-million chance of error, this is enough for physicists to declare that the Higgs Boson—the world’s most-wanted particle—has been discovered. In the vicinity of Geneva, Switzerland, jubilant applause and cheers filled every corner of the CERN auditorium.
Nearly 50 years after scientists first predicted the existence of the Higgs boson, this breakthrough means that the “Standard Model of Particle Physics,” a physical model capable of explaining all known particles and the forces acting upon them, is now complete.
The head of the experiment announced today at CERN: the mass of the Higgs boson is between 125 and 126 GeV. It was observed separately by the Large Hadron Collider’s (LHC) two twin detectors—CMS and ATLAS. The error for each detector is 5 sigma. (Sigma represents relative error, representing five parts in ten million; relative to 125 GeV, it is 5 eV). Even by the strict standards of particle physicists, it has enough significance to be regarded as the discovery of a particle.
“I think we have found it,” said CERN Director-General Rolf Heuer. He reached this conclusion during a highly-anticipated seminar held at 9:00 AM local time. The results were presented to the world at the International Conference on High Energy Physics (ICHEP) held in Melbourne, Australia.
Ducks in a Line
Pier Oddone, director of Fermilab in Chicago, Illinois (where the now-defunct Tevatron accelerator is located), expressed his view on the discovery from another perspective. “If it looks like a duck and walks like a duck, then it is a duck,” he said.
Joe Incandela of CMS and Fabiola Gianotti of ATLAS reported support, having discovered excess particles that exactly match the characteristics of a Higgs boson with a mass between 125 and 126 GeV. They are confident the error is only 5 sigma—their announcements triggered a standing ovation from those present! The results generally satisfy the reports made by the two teams in December, when they found “traces” of the Higgs boson but lacked sufficient data for statistical significance.
Last night, around 11:00 PM, people began queuing to enter the auditorium, even setting up tents outside. Many who started queuing this morning were turned away because there was simply no more space. Over the past few days, rumors, leaks, and hype surrounding this event have been rampant—and the fact is that this discovery is in principle just a collection of data—though we have the most gratifying confidence in these highly-watched “products,” the current encouraging Higgs boson detection results are not a complete surprise.
The Most Fundamental
The Higgs boson gives mass to all elementary particles, allowing for the existence of matter. It is the fundamental unit, or quantum, of the Higgs field (a physical field that all particles must pass through). Some particles, such as photons, can easily escape it—because they have no mass; however, other particles must struggle to break free from it, like butterflies stuck in syrup. The Standard Model requires the Higgs boson and the field it composes, but before today’s report, they had never been definitively detected.
The seminar was filled with excitement. Peter Higgs, who first predicted the Higgs boson in 1964, called it “the most incredible thing in my life.”
But physicists are reluctant to call it the discovery of the “Higgs boson,” preferring instead to call it the discovery of a “new boson.” This is because they do not yet understand its characteristics—likewise, they cannot yet confirm exactly how similar it is to the Higgs boson of the Standard Model. “Now is the beginning of a long journey to explore the characteristics of this boson,” Heuer pointed out. One characteristic that must be understood is the spin of this boson: the Standard Model holds that its value must be 0; whereas the spin of some more exotic bosons is 2. Oliver Buchmueller of CMS said that by the end of this year, the LHC should be able to determine the spin of this new boson.
We know that the Standard Model is still incomplete—from the beginning, it did not include dark matter and gravity—so a non-Standard Model Higgs boson would be very exciting.
“Everyone is not only happy because of the discovery itself, but also excited because of the prospects this discovery brings to the field,” Heuer said.
English Original Text
http://www.newscientist.com/article/dn22014-celebrations-as-higgs-boson-is-finally-discovered.html
Celebrations as Higgs boson is finally discovered
11:52 04 July 2012 by Celeste Biever, CERN, Geneva
There’s a 5-in-10 million chance that this is a fluke. That was enough for physicists to declare that the Higgs boson – the world’s most-wanted particle – has been discovered. Rapturous applause, whistles and cheers filled the auditorium at CERN, near Geneva, Switzerland.
Almost 50 years after its existence was first predicted, the breakthrough means that the standard model of particle physics, which explains all known particles and the forces that act upon them, is now complete.
A Higgs boson with a mass of around 125 to 126 gigaelectronvolts (GeV) was seen separately by the twin CMS and ATLAS detectors at the Large Hadron Collider, each with a confidence level of 5 sigma, or standard deviations, the heads of the experiments announced today at CERN.
Even by particle physicists’ strict standards, that’s statistically significant enough to count as a particle discovery.
"I think we have it," said Rolf Heuer, director general of CERN, as he concluded a hotly-anticipated seminar, which began today at 9am local time.
Around the world the results were being watched at the International Conference on High Energy Physics in Melbourne, Australia.
Ducks in a line
Pier Oddone, director of Fermilab near Chicago, Illinois, home of the now-defunct Tevatron collider, expressed his views on the discovery in a different way. "If it looks like a duck and it walks like a duck it’s going to be a duck," he said.
Joe Incandela of CMS and Fabiola Gianotti of ATLAS reported seeing excesses of particles that fit the profile of a Higgs with a mass of 125 and 126 GeV respectively. Both claimed 5 sigma confidence in the result – and both announcements were met by standing ovations.
That result broadly agrees with earlier, less statistically significant "hints" of the Higgs reported by the same two teams in December.
People started queuing to get into the auditorium at about 11pm last night, camping out. Many of those who started queuing this morning were turned away because there wasn’t room.
Given a flurry of rumours, leaks and hype over the past few days – and the fact that a discovery was in principle possible given the volume of data collected – the positive Higgs result is not a complete surprise, though the confidence we can have in the result is the best of the anticipated outcomes.
It’s elementary
The Higgs boson gives all elementary particles mass, allowing for the existence of matter. It is the fundamental unit, or quantum, of the Higgs field, an all pervading entity that all particles must pass through.
Some, like the photon, slip through unhindered – they are massless. Others, though, must struggle like a fly trapped in treacle. The Higgs and its field are required by the standard model, but had never been conclusively detected before today’s report.
The seminar was full of emotion and elation. An emotional Peter Higgs, who postulated the boson that is his namesake in 1964, called it "an incredible thing that happened in my lifetime".
The physicists were a little reticent to call the discovery a "Higgs boson", preferring to call it the discovery of a "new boson".
That’s because they don’t yet know its properties – and so can’t confirm how similar it is to the Higgs of the standard model. "It’s the beginning of a long journey to investigate all the properties of this particle," says Heuer.
One property that needs to be investigated is the particle’s spin: the standard model says it should have a value of zero; a more exotic boson would give a value of two. Oliver Buchmueller of CMS says the LHC should be able to determine the new boson’s spin by the end of 2012.
We know that the standard model is not complete – it does not contain dark matter or gravity, for a start – so a non-standard model Higgs could be very exciting.
"Everyone is not just excited about the discovery, but about the prospects this discovery offers to the field," says Heuer.
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