quinta-feira, 21 de fevereiro de 2013

Higgs may spell doom, unless supersymmetry saves us

Short Sharp Science: Higgs may spell doom, unless supersymmetry saves us


http://www.newscientist.com/blogs/shortsharpscience/2013/02/higgs-may-spell-doom-unless-a.html

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'' Is the Higgs boson a herald of the apocalypse? That's the suggestion behind a theory, developed more than 30 years ago, that is back in the headlines this week. According to physicists, the mass of the Higgs-like particle announced last summer supports the notion that our universe is teetering on the edge of stability, like a pencil balanced on its point.
"It may be that the universe we live in is inherently unstable," Joseph Lykken, of the Fermi National Accelerator Laboratory in Batavia, Illinois, said on Monday at a meeting of theAmerican Association for the Advancement of Science. "At some point, billions of years from now, it's all going to be wiped out."
Physicists have been wringing their hands about this scenario since 1982, when theorists Michael Turner and Frank Wilczek published a paper about it in NatureNBC News points out. The pair showed that the vacuum of space can be in different energy states, and it will be most stable at its lowest energy. Trouble arises if we're not there yet, and we're inhabiting a temporarily stable state that should ultimately collapse.
"The universe wants to be in a different state, so eventually to realise that, a little bubble of what you might think of as an alternate universe will appear somewhere, and it will spread out and destroy us," Lykken said at AAAS.
Enter the Higgs boson, the particle form of the field that gives mass to several fundamental particles. The Higgs field permeates the vacuum of space, which means the mass of the boson and the stability of the vacuum are closely intertwined. Theory predicted that if the Higgs boson is heavier than about 129 gigaelectronvolts (GeV), the universe should be on safe footing.
But in July 2012 physicists at CERN, near Geneva, Switzerland, announced that a particle closely matching the Higgs had been found by experiments in the Large Hadron Collider (LHC). The much celebrated particle has a mass of about 126 GeV - light enough to raise fears of instability.
There is still hope for the universe as we know it. Some theorists pointed out that the relationship between the Higgs mass and the vacuum of space depends on the mass of a particle called the top quark. If the top quark's mass is different than we think it is, stability might reign.
There are also anomalies with the Higgs measurement, like the fact that it decays into photons more often than predicted. That hints we may yet find particles from the theory of supersymmetry, which says each ordinary particle has heavier "superpartners". If the Higgs has such a relative, it might save us from destruction. But some of these predicted particles, particularly the superpartners of the top quark, can push the universe back into instability.
The worries may remain unconfirmed for a while. The LHC is shutting down for a two-year break so engineers can prepare the machine to shoot higher-energy particle beams, which are needed to probe for superpartners. ''

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