Seldom has something so small and ephemeral excited such interest. The theoretical particle explains how suns and planets formed after the Big Bang - but so far it has not been proven to exist.

The CERN research centre near Geneva will on July 4 unveil its latest findings in the search for the Higgs after reporting "tantalizing glimpses" in December.

Scientific bloggers and even some of the thousands of physicists working on the project are speculating that CERN will finally announce proof of the existence of the Higgs.

"It's still premature to say anything so definitive," says CERN spokesman James Gillies, adding the two teams involved are still analyzing data and even CERN insiders won't know the answer until the results from both are brought together.

But with plans for a news conference that will be beamed live around the world and coincide with a major particle physics conference in Melbourne, Australia, anticipation of a significant announcement is hard to avoid.

For Jordan Nash, a professor at London's Imperial College and a member of one of the teams looking for the Higgs, the excitement around the experiment is justified.

"We're trying to understand the fabric of the universe itself," he told Reuters. "It's a hugely fundamental piece of the mystery of how the universe is put together."

SMASHING WATERMELONS

A definitive 'we've found it' would be a surprise and a major scientific milestone.

"We too are holding our breath," says Pauline Gagnon, a Canadian physicist on one of the teams, in her latest blog.

The action takes place in the Large Hadron Collider, the world's biggest and most powerful particle accelerator, a 27-km (17-mile) looped pipe that sits in a tunnel 100 meters underground on the Swiss/French border.

Two beams of energy are fired in opposite directions around it before smashing into each other to create many millions of particle collisions every second in a recreation of the conditions a fraction of a second after the Big Bang.

The vast amount of data produced is examined by banks of computers. But it's a messy process. For all the billions of collisions, very few of them are just right for revealing the Higgs particle.

"It's like smashing watermelons together and trying to achieve a perfect collision for two of the pips inside," says Nash.

Last year's "glimpses" of the Higgs were from just a handful of collisions out of the many millions that were analyzed. Since then, the power inside the collider has been ramped up to increase the intensity of the particle smashing. This threw off more data between April and June than in the whole of last year.

"We're looking for something so rare, it's a sifting experiment," Nash said. "We just made a gigantic haystack and now we are looking for the needle".

IT'S A BIG UNIVERSE

The Higgs particle is a crucial plank of the Standard Model, which is the best explanation physicists have of how the universe works at the most fundamental level.

But the particle is theoretical, first posited in 1964 by British scientist Peter Higgs as the way matter obtained mass after the universe was created 13.7 billion years ago.

Without it, according to the theory, the universe would have remained a giant soup of particles. It would not have coalesced into stars, planets and life.

Even if its existence is finally proven, it will only apply to the relatively small part of the universe explained by the Standard Model. It won't tell us about so-called dark matter or dark energy, which scientists believe make up about 96 percent of the cosmos.

It could, however, be a step towards a theory of everything that encompasses dark matter and energy, as well as the force of gravity, which the Standard Model also does not explain.

Those early glimpses may of course not be borne out in the latest data, which would provoke serious head-scratching and debate about where to look next. They may discover the Higgs exactly as postulated.

But scientists say the most exciting news from CERN, whether it comes next week or later this year, would be the discovery of a type of Higgs particle but not quite as described in the Standard Model.

This, they say, could provide a road sign on where to look for answers on dark matter, dark energy and even esoteric concepts like parallel universes.

"Something more exotic could take us beyond the Standard Model and into the rest of the universe that we currently know nothing about," said James Gillies.

He said just as Albert Einstein's theories enveloped and built on the work of Isaac Newton, the work being done by the thousands of physicists at CERN has the potential to do the same. "It's where we'd like it to take us," he said.

WHO CARES?

In a hard-up world paying the bill for multiple financial crises, some question the value of big science projects like the Large Hadron Collider and scientists feel an ever increasing pressure to justify the expense to policymakers. The LHC cost about 3 billion euros to build.

CERN's highest profile gift to the real economy was the source code for the World Wide Web, written by scientist Tim Berners-Lee when he worked at the research centre in the 1990s.

Asked what the Higgs hunt could bestow on the world, Nash says the research is too leading edge and too nascent to say. At this point it's about the thirst for knowledge, something he argues the public well understands.

"We do bring a lot of things back," he says. "But when I talk to taxi drivers or builders they never ask that."

(Editing by Janet Lawrence)

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