CERN Reports Hints of the Higgs Particle -The Missing Member of the Standard Model of the Universe

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"It's very exciting. This could be the first ring in a chain of discoveries."

CMS spokesman Guido Tonelli.

CERN has announced that both of the main LHC detectors, ATLAS and CMS (Compact Muon Solenoid) experiment, have uncovered hints of a lightweight Higgs. he most coveted prize in particle physics – the Higgs boson – may have been glimpsed, say researchers reporting at the Large Hadron Collider (LHC) in Geneva. The particle is purported to be the means by which everything in the Universe obtains its mass. But the LHC does not yet have enough data to claim a discovery.


Finding the Higgs is crucial for allowing us to make sense of the Universe, but has never been observed by experiments. The Higgs is a sub-atomic particle that was proposed as a mechanism to explain mass by six physicists, including Peter Higgs, in 1964 It imparts mass to other fundamental particles via the associated Higgs field It is the last missing member of the Standard Model – the "instruction booklet" that describes how particles and forces interact.

If it proves true, the only remaining gap in the standard model would be filled. A Higgs of this mass, about 125 gigaelectronvolts, would also provide a bridge to uncharted supersymmetry terrain. This lightweight Higgs would need at least one new type of particle to stabilise it.

As the leading theory for how particles and forces interact, the standard model works only on the assumption that the Higgs boson –thought to give all particles their mass–actually exists. The huge challenge has been that the standard model cannot predict what the Higgs itself weighs.
Years of experiments have steadily ruled it out except for a narrow range between 115 and 141 GeV.

Tonelli and Fabiola Gianotti, head of the ATLAS detector, separately presented results of the two seperate experiments from more than 300 trillion high-speed particle collisions made in the last year.

"This is the first time we're really exploring the entire [mass] region with the right sensitivity – the one that will allow you, if there is something there, to start seeing something," says Tonelli.

ATLAS saw an exciting hint of the Higgs at 126 GeV and CMS saw one at 124 GeV –the first time both experiments have seen a signal at nearly the same mass.

"We're very competitive, but once I see they're coming with results, I'm happy," Tonelli says. "Their results are important for us. They're obtained in a completely independent manner."

Although both teams see an excess around the same mass, there is not yet enough data to claim a discovery. The ATLAS signal has a statistical significance at 126 GeV of 2.3 sigma, meaning that the result has around a 2 per cent chance of being down to a random fluctuation. Meanwhile,
the comparable excess at CMS has a significance of just 1.9 sigma.

To confirm a discovery you need a 5 sigma signal, meaning there is less than 1 in a million chance of the result being a fluke. "There's clearly not enough to conclude anything at this stage," Gianotti says. "It could be something interesting, or just a fluctuation."

Thanks to subtle quantum mechanical effects, a lightweight Higgs needs a heavier companion particle "acting as a sort of bodyguard", Tonelli says. Otherwise, the quantum vacuum from which particles appear would be unstable, and the universe would long ago have disintegrated. If the Higgs is lightweight, the fact that we are here today suggests there is at least one extra particle beyond the standard model.

Going forward, assuming the collider keeps working well, both experiments should have enough data to confirm or deny the simplest version of the Higgs by the end of 2012. However. Iif the current hints in the data  disappear, physicists will wait until the LHC revs up to its full energy in 2015 to look for other particles or phenomena that could give particles mass without any need for the Higgs.

"There must be something else that plays that role," Gianotti says. "We will be after that something else."

The Daily Galaxy via http://www.bbc.co.uk/news/science-environment-16158374 and newscientist.com

CERN Reports Hints of the Higgs Particle -Tthe Last Missing Member of the Standard Model of the Universe

"It's very exciting. This could be the first ring in a chain of discoveries."

CMS spokesman Guido Tonelli.

CERN has announced that both of the main LHC detectors, ATLAS and CMS (Compact Muon Solenoid) experiment, have uncovered hints of a lightweight Higgs. he most coveted prize in particle physics – the Higgs boson – may have been glimpsed, say researchers reporting at the Large Hadron Collider (LHC) in Geneva. The particle is purported to be the means by which everything in the Universe obtains its mass. But the LHC does not yet have enough data to claim a discovery.

Finding the Higgs is crucial for allowing us to make sense of the Universe, but has never been observed by experiments.

The Higgs is a sub-atomic particle that was proposed as a mechanism to explain mass by six physicists, including Peter Higgs, in 1964 It imparts mass to other fundamental particles via the associated Higgs field It is the last missing member of the Standard Model – the "instruction booklet" that describes how particles and forces interact.

If it proves true, the only remaining gap in the standard model would be filled. A Higgs of this mass, about 125 gigaelectronvolts, would also provide a bridge to uncharted supersymmetry terrain. This lightweight Higgs would need at least one new type of particle to stabilise it.

As the leading theory for how particles and forces interact, the standard model works only on the assumption that the Higgs boson –thought to give all particles their mass–actually exists. The huge challenge has been that the standard model cannot predict what the Higgs itself weighs.
Years of experiments have steadily ruled it out except for a narrow range between 115 and 141 GeV.

Tonelli and Fabiola Gianotti, head of the ATLAS detector, separately presented results of the two seperate experiments from more than 300 trillion high-speed particle collisions made in the last year.

"This is the first time we're really exploring the entire [mass] region with the right sensitivity – the one that will allow you, if there is something there, to start seeing something," says Tonelli.

ATLAS saw an exciting hint of the Higgs at 126 GeV and CMS saw one at 124 GeV –the first time both experiments have seen a signal at nearly the same mass.

"We're very competitive, but once I see they're coming with results, I'm happy," Tonelli says. "Their results are important for us. They're obtained in a completely independent manner."

Although both teams see an excess around the same mass, there is not yet enough data to claim a discovery. The ATLAS signal has a statistical significance at 126 GeV of 2.3 sigma, meaning that the result has around a 2 per cent chance of being down to a random fluctuation. Meanwhile,
the comparable excess at CMS has a significance of just 1.9 sigma.

To confirm a discovery you need a 5 sigma signal, meaning there is less than 1 in a million chance of the result being a fluke. "There's clearly not enough to conclude anything at this stage," Gianotti says. "It could be something interesting, or just a fluctuation."

Thanks to subtle quantum mechanical effects, a lightweight Higgs needs a heavier companion particle "acting as a sort of bodyguard", Tonelli says. Otherwise, the quantum vacuum from which particles appear would be unstable, and the universe would long ago have disintegrated. If the Higgs is lightweight, the fact that we are here today suggests there is at least one extra particle beyond the standard model.

Going forward, assuming the collider keeps working well, both experiments should have enough data to confirm or deny the simplest version of the Higgs by the end of 2012. However. Iif the current hints in the data  disappear, physicists will wait until the LHC revs up to its full energy in 2015 to look for other particles or phenomena that could give particles mass without any need for the Higgs.

"There must be something else that plays that role," Gianotti says. "We will
be after that something else."

The Daily Galaxy via bbc.co.uk and newscientist.com

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