CERN scientists say particle is no "super-Higgs"

By Robert Evans

GENEVA (Reuters) - 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. (Editing by Robin Pomeroy)

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Hopes fade of Higgs particle opening door to new realms soon

GENEVA (Reuters) - Scientists' hopes that last summer's triumphant trapping of the particle that shaped the post-Big Bang universe would quickly open the way into exotic new realms of physics like string theory and new dimensions have faded this past week.

Five days of presentations on the particle, the Higgs boson, at a scientific conference high in the Italian Alps point to it being the last missing piece in a 30-year-old cosmic blueprint and nothing more, physicists following the event say.

"The chances are getting slimmer and slimmer that we are going to see something else exciting anytime soon," said physicist Pauline Gagnon from CERN near Geneva in whose Large Hadron Collider (LHC) the long-sought particle was found.

And U.S. scientist Peter Woit said in his blog that the particle was looking "very much like a garden variety SM (Standard Model) Higgs", discouraging for researchers who were hoping for glimpses of breathtaking vistas beyond.

That conclusion, shared among analysts of vast volumes of data gathered in the LHC over the past three years, would push to well beyond 2015 any chance of sighting exotica like dark matter or super symmetric particles in the giant machine.

That is when the LHC, where particles are smashed together at light speed to create billions of mini-Big Bangs that are traced in vast detectors, resumes operation with its power doubled after a two-year shutdown from last month.

The Higgs - still not claimed as a scientific discovery because its exact nature has yet to be established - was postulated in the early 1960s as the element that gave mass to flying matter after the Big Bang 13,7 billion years ago.

UNEXPLAINED MYSTERIES

It was incorporated tentatively into the Standard Model when that was compiled in the 1980s, and its discovery in the LHC effectively completed that blueprint. But there are mysteries of the universe, like gravity, that remain outside it.

Some physicists have been hoping that the particle as finally found would be something beyond a "Standard Model Higgs" - offering a passage onwards into a science fiction world of "New Physics" and a zoo of new particles.

They had been looking to the Italian gathering, called the Moriond Conference although it is held in the ski village of La Thuile, for reports bringing evidence of this.

Dark matter, the invisible stuff that makes up some 25 percent of the universe, and super symmetry, a theory that says all particles have unseen extra-heavy counterparts, were top of the target list after the finding of the Higgs.

Both are integral parts of the concept of "New Physics" that should take knowledge of how the universe works beyond that of the Standard Model blueprint.

There is little or no controversy about dark matter, whose existence is deduced from its gravitational influence on the visible galaxies, stars and planets which make up little more than four percent of the cosmos.

But super symmetry, dubbed SUSY by physicists, is controversial, championed by some physicists and dismissed as fantasy by others - like the string theory on how the universe is built, with which it is linked.

One of its proponents, Oliver Buchmueller of CERN's CMS research team, on Friday accepted that finding it would now take longer. "It seems we have to wait for 2015 and higher energy. That will be the showdown for Susy," he told Reuters.

(Reported by Robert Evans; editing by Andrew Roche)

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