Wednesday, March 13, 2013

CERN scientists say particle is no "super-Higgs"

Physicists who found a new elementary particle last year said on Wednesday it looked like a basic Higgs boson rather than any "super-Higgs" that some cosmologists had hoped might open up more exotic secrets of the universe.

"It does look like the SM (Standard Model) Higgs boson," said physicist Brian Petersen of Atlas, one of two research teams working in parallel on the Higgs project at CERN in Switzerland.

His assertion, on a slide presentation to a conference at CERN and posted on the Internet, was echoed by the other group. "So far, it is looking like an SM Higgs boson," said slides from Colin Bernet of CMS.

The two groups work separately and without comparing findings to ensure their conclusions are reached independently.

It has been assumed since the triumphant announcement last June that a new particle spotted at CERNS's Large Hadron Collider (LHC) was the Higgs, named after British theoretical physicist Peter Higgs, that, theories say, gave mass to matter after the Big Bang 13.7 billion years ago.

But CERN has yet to confirm that. CMS may issue more information on Thursday at an expert gathering in the Italian Alps. A confirmed discovery of the Higgs boson, which could happen this year, would likely win a Nobel prize.

Meeting at CERN, near Geneva, the scientists said on Wednesday that the particle looked very much like it fit into the 30-year-old Standard Model of the makeup of the universe.

If confirmed on Thursday, it would mean LHC scientists will have to wait until late in this decade for any sign of "new worlds of physics".

Until the last few days there had been some faint signs that the discovery might prove to be something more than the particle that would fill the last gap in the Standard Model, a comprehensive explanation of the basic composition of the universe.

Rumours flew of a "super-Higgs" that might - as recently predicted by U.S. physicist Sean Carroll in a book on the particle - "be the link between our world and most of the matter in the universe."

Many scientists and cosmologists will be disappointed that the LHC's preliminary 3-year run from March 2010 to last month has not produced evidence of the two grails of "new physics" - dark matter and supersymmetry.

Dark matter is the mysterious substance that makes up some 25 percent of the stuff of the universe, against the tiny 4 percent - galaxies, stars and planets - which is visible. The remainder is a still unexplained "dark energy."

The theory of supersymmetry predicts that all elementary particles have heavier counterparts, also yet to be seen. It links in with more exotica like string theory, extra dimensions, and even parallel universes.

"I think everyone had hoped for something that would take us beyond the Standard Model, but that was probably not realistic at this stage," said one researcher, who asked not to be named.

The LHC closed down last month for two years of work that will double its power, and, it is hoped, the reach of its detectors.