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The LHC is the single most expensive piece of scientific equipment in the history of mankind.  (Source: FermiLab)
Scientists are still grappling with whether Standard Model of particle physics still applies

It took the construction of the most expensive piece of laboratory equipment in the history of mankind (with a sticker price of $10B USD), but last July the European Organization for Nuclear Research (CERN) reported that it was 99.99997% sure that it had found the Higgs boson -- an incredibly elusive yet critical subatomic particle that creative members of the media dubbed "the God Particle".

I. After Analyzing More Data, CERN is More Certain it Saw a Higgs Boson

The results from the Large Hadron Collider (LHC) validated an earlier 99.8 percent (roughly 3σ) sure spotting by the U.S. Department of Energy's now-defunct Tevatron at FermiLab.

Now researchers have ratcheted up the certainty even higher.  Researchers with CERN have combed through two and a half times more data since last July, examining the results from the ATLAS and CMS.  Among the things measured were the interactions between the particles created, the parity of the created particles, and their spin.

The Higgs boson in most models is expected to have no spin.  Likewise, the new mystery particle observed in record 7 TeV and 8 TeV proton collisions had no spin.  CMS spokesperson Joe Incandela comments, "The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is."

As Mr. Incadela suggests, the bigger question was whether this was the Higgs boson predicted by the prevailing theory of particle physics -- the Standard Model -- or whether the evidence pointed to an alternate theory.  As they say, the devil is in the details.

II. But What Kind?

When it came to the "God particle" those details point to the Standard Model being correct.  The Standard Model predicts a positive parity, and likewise the detectors indicated the mystery particle to have a positive parity.

Comments ATLAS spokesperson Dave Charlton, "The beautiful new results represent a huge effort by many dedicated people. They point to the new particle having the spin-parity of a Higgs boson as in the Standard Model. We are now well started on the measurement programme in the Higgs sector."

Higgs boson observation
A CMS detector view of a Higgs boson creation from a 8 TeV collision. [Image Source: CERN]

In a sense, there's no right or wrong answer when it comes to the identity of the Higgs boson -- only the quest for the truth.  The LHC has previously provided evidence that some aspects of supersymmetry theory are flawed and need to be reworked.  By contrast the Higgs boson parity results appear to confirm the prevalent theory.

Atlas Higgs
An ATLAS detector view of a Higgs boson creation from a 8 TeV collision.
[Image Source: CERN]

With the parity certain, the last piece of evidence that researchers need to determine that it's the Standard Model Higgs boson is to make sure its observed decays match those predicted by the Standard Model.  To do that, the researchers will have to log more high power tests with the LHC. The Higgs boson is only created once every trillion (1012) proton-proton collisions, or so.  As it can presumably decay in many ways, scientists will need to create more Higgs boson and observe their decays in order to fully verify that the Standard Model holds true.

 Nebula wide
Finding the Higgs boson is a major step on the road to discovering the secrets of the universe.
[Image Source: NASA]
 
For now researchers are very sure they found the Higgs boson, but only "pretty sure" that the critical Standard Model theory is correct.

Source: CERN



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RE: I never get tired of it
By Quadrillity on 3/14/2013 4:09:26 PM , Rating: 2
Nice


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