By Robert Evans
GENEVA (Reuters) - Physicists who last summer triumphantly announced the discovery of a new particle but held back from saying what it was, declared on Thursday there was now little doubt it was the long-sought Higgs boson.
Latest analysis of data from the Large Hadron Collider (LHC) particle accelerator, where the boson was spotted as a bump on a graph early in 2012, "strongly indicates" it is the Higgs, said CERN, the European Organisation for Nuclear Research.
Physicists believe the boson and its linked energy field were vital in the formation of the universe after the Big Bang 13.7 billion years ago by bringing flying particles together to make stars, planets and eventually humans - giving mass to matter, in the scientific jargon.
The particle and the field, named for British physicist Peter Higgs who predicted their existence 50 years ago, are also the last major missing elements in what scientists call the Standard Model of how the cosmos works at the very basic level.
But the CERN statement stopped short of claiming a discovery - which would clear the way to Nobel prizes for scientists linked to the project - and floated the idea that this might be an exotic "super-Higgs" offering a key to new worlds of physics.
"It remains an open question whether this is the Higgs boson of the Standard Model ... or possibly the lightest of several bosons predicted in some theories that go beyond the Standard Model," said CERN, a large complex on the edge of Geneva.
"Finding the answer to this question will take time."
Although some CERN physicists privately expressed irritation at the continuing refusal to - as one said - "call a Higgs a Higgs", others argued that this could only come when the evidence was all totally irrefutable.
If it is not what one CERN-watching blogger has dubbed a "common or garden Higgs" but something more complex, vistas into worlds of supersymmetry, string theory, multiple dimensions and even parallel universes could begin to unfold.
WHAT KIND OF HIGGS?
"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," said Joe Incandela, spokesman for CMS, one of the two independent CERN LHC monitoring teams.
"There is every possibility that it is a Higgs boson from a more complex model, such as supersymmetry (a theory which says every elementary particle has a so-far unseen heavier partner)," another CMS researcher, John Conway, told Reuters.
In recent months, rumors have flown that the particle might be some sort of super-Higgs - "the link between our world and most of the matter in the universe" as predicted by U.S. physicist Sean Carroll in a new book.
But David Charlton, who speaks for the ATLAS team, said the latest analysis, presented on Thursday to a conference in the Italian Alps, pointed to the particle fitting the Standard Model - which would exclude exotica.
However, CERN scientists agree nothing startlingly new could be expected until much later in the decade, well after the LHC - shut down last month for two years to allow its power and reach to be doubled - resumes operations in early 2015.
In the giant subterranean collider, which started up in March 2010, particles are smashed together hundreds of times a second at near the speed of light to simulate the Big Bang. The debris is then tracked on huge detectors.
But the new particle turns up only once in every trillion collisions - leaving the thousands of physicists and analysts at CERN, and in laboratories around the world, the massive task of deciding what data to discard.
(Reporting by Robert Evans; Editing by Pravin Char)