Scientists may make definitive Higgs boson announcement in March

* Alpine physics conference could host announcement

* Researchers play down speculation of 'twin' particles

* Discovery claim could bring Nobel prize

GENEVA, Dec 19 (Reuters) - Scientists at Europe's CERN

research centre said on Wednesday they may be able to

definitively announce at a conference next March that they had

discovered the elusive Higgs boson.

But they dismissed suggestions circulating widely on blogs

and even in some science journals that instead of just one type

of the elementary particle they might have found a pair.

CERN researchers said in July they had found what appeared

to be the particle that gives mass to matter, as imagined and

named half a century ago by theoretical physicist Peter Higgs.

But they stopped short of saying for sure it was the Higgs

boson, pending further research.

"The latest data we have on this thing we have been watching

for the past few months show that it is not simply 'like a

Higgs' but is very like a Higgs," said Oliver Buechmuller of the

CMS team at CERN's Large Hadron Collider.

"The way things are going, by the Moriond meeting we may be

able to stop calling it Higgs-like and finally say it is the

Higgs," he told Reuters, referring to the annual gathering which

will take place at the Italian Alpine resort of La Thuile, 120

kms (75 miles) from CERN, on March 2-9.

Suggestions that there may be two Higgs, a particle that

made formation of the universe possible after the Big Bang 13.7

billion years ago, emerged after a progress report by CERN

scientists last week. Its definitive discovery that would almost

certainly win a Nobel Prize.

Commentators, including one in the journal Scientific

American, said differing measurements - so far unexplained - of

the new boson's mass that were recorded by ATLAS - a parallel

but separate research team to CMS at CERN, indicated there might

be twin particles.

"That is quite an exaggeration," said Pauline Gagnon, a

scientist with ATLAS. "The facts are so much simpler: we measure

one quantity in two different ways and obtain two slightly

different answers.

"However, when we combine all the information, we clearly

get only one value. Since we have checked all other

possibilities, it really looks like a statistical fluctuation.

Such things happen."

Buechmueller, whose CMS team found no such variation in

their measurements, said he agreed there was no special

relevance in the ATLAS discrepancy. "It will probably disappear

when more data is in and analysed," he added.

The $10-billion Large Hadron Collider, a 27-km (17-mile)

circular construct deep under the Franco-Swiss border, will shut

down for some two years in February to allow a doubling of its

power and its capacity to probe cosmic mysteries

(Reported by Robert Evans; Editing by Robin Pomeroy)