After a quest spanning nearly half a century, physicists on Wednesday said they had found a new sub-atomic particle consistent with the Higgs boson which is believed to confer mass.
Rousing cheers and a standing ovation broke out at the European Organisation for Nuclear Research (CERN) after scientists presented data in their long search for the mysterious particle.
The new find is "consistent with (the) long-sought Higgs boson," CERN declared in a statement.
It added further data was needed to identify the find.
"We have reached a milestone in our understanding of nature," said CERN Director General Rolf Heuer.
"The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle's properties, and is likely to shed light on other mysteries of our Universe."
Peter Higgs, a shy, soft-spoken British physicist who published the conceptual groundwork for the particle, back in 1964, expressed joy.
"I never expected this to happen in my lifetime and shall be asking my family to put some champagne in the fridge," he said in a statement issued by the University of Edinburgh, where he was a professor.
Finding the Higgs would validate the Standard Model, a theory which identifies the building blocks for matter and the particles that convey fundamental forces.
It is a hugely successful theory but has several gaps, the biggest of which is why some particles have mass but others do not.
Mooted by Higgs and several others, the boson is believed to exist in a treacly, invisible, ubiquitous field created by the Big Bang some 13.7 billion years ago.
When some particles encounter the Higgs, they slow down and acquire mass, according to the theory. Others, such as particles of light, encounter no obstacle.
CERN uses a giant underground laboratory where protons are smashed together at nearly the speed of light, yielding sub-atomic debris that is then scrutinised for signs of the fleeting Higgs.
The task is arduous because there are trillions of signals, occurring among particles at different ranges of mass.
Over the years, tens of thousands of physicists and billions of dollars have been thrown into the search for the Higgs, gradually narrowing down the mass range where it might exist.Two CERN laboratories, working independently of each other to avoid bias, found the new particle in the mass region of around 125-126 Gigaelectronvolts (GeV), according to data they presented on Wednesday.
Both said that the results were "five sigma," meaning there was just a 0.00006 percent chance that what the two laboratories found is a mathematical quirk.
"The results are preliminary but the five sigma signal at around 125 GeV we're seeing is dramatic," said Joe Incandela, spokesman for one of the two experiments.
"This is indeed a new particle. We know it must be a boson and it's the heaviest boson ever found. The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks."
Scientists began to pore over what the historic find could mean.
"(The Higgs) has been anticipated for more than four decades and were it not there theorists all over the world would have been back to their drawing boards in desperation," said Anthony Thomas at the University of Adelaide in Australia.
CERN physicist Yves Sirois agreed.
"This could the Higgs boson that has been found, which may shed light on how matter came into being at the very start of the Universe, a thousandth of a billionth of a second after the Big Bang," he told AFP."It may be the Higgs boson, but it may also be something far bigger, which opens the door towards a new theory that goes beyond the Standard Model."
What Is The Higgs Boson?
The Higgs is the last missing piece of the Standard Model, the theory that describes the basic building blocks of the universe. The other 11 particles predicted by the model have been found and finding the Higgs would validate the model. Ruling it out or finding something more exotic would force a rethink on how the universe is put together.
Scientists believe that in the first billionth of a second after the Big Bang, the universe was a gigantic soup of particles racing around at the speed of light without any mass to speak of. It was through their interaction with the Higgs field that they gained mass and eventually formed the universe.
The Higgs field is a theoretical and invisible energy field that pervades the whole cosmos. Some particles, like the photons that make up light, are not affected by it and therefore have no mass. Others are not so lucky and find it drags on them as porridge drags on a spoon.
Picture George Clooney (the particle) walking down a street with a gaggle of photographers (the Higgs field) clustered around him. An average guy on the same street (a photon) gets no attention from the paparazzi and gets on with his day. The Higgs particle is the signature of the field - an eyelash of one of the photographers.
The particle is theoretical, first posited in 1964 by six physicists, including Briton Peter Higgs.
The search for it only began in earnest in the 1980s, first in Fermilab's now mothballed Tevatron particle collider near Chicago and later in a similar machine at CERN, but most intensively since 2010 with the start-up of the European centre's Large Hadron Collider.
What Is The Standard Model?
The Standard Model is to physics what the theory of evolution is to biology. It is the best explanation physicists have of how the building blocks of the universe are put together. It describes 12 fundamental particles, governed by four basic forces.
But the universe is a big place and the Standard Model only explains a small part of it. Scientists have spotted a gap between what we can see and what must be out there. That gap must be filled by something we don't fully understand, which they have dubbed 'dark matter'. Galaxies are also hurtling away from each other faster than the forces we know about suggest they should. This gap is filled by 'dark energy'. This poorly understood pair are believed to make up a whopping 96% of the mass and energy of the cosmos.
Confirming the Standard Model, or perhaps modifying it, would be a step towards the holy grail of physics - a 'theory of everything' that encompasses dark matter, dark energy and the force of gravity, which the Standard Model also does not explain. It could also shed light on even more esoteric ideas, such as the possibility of parallel universes.
CERN spokesman James Gillies has said that 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 to Einstein's work.
What Is The Large Hadron Collider?
The Large Hadron Collider is the world's biggest and most powerful particle accelerator, a 27-km (17-mile) looped pipe that sits in a tunnel 100 metres underground on the Swiss/French border. It cost 3 billion euros to build.
Two beams of protons 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, when the Higgs field is believed to have 'switched on'.
The vast amount of data produced is examined by banks of computers. Of all the trillions of collisions, very few are just right for revealing the Higgs particle. That makes the hunt for the Higgs slow, and progress incremental.
What Is The Threshold For Proof?
To claim a discovery, scientists have set themselves a target for certainty that they call "5 sigma". This means that there is a probability of less than one in a million that their conclusions from the data harvested from the particle accelerator are the result of a statistical fluke.
The two teams hunting for the Higgs at CERN, called Atlas and CMS, now have twice the amount of data that allowed them to claim 'tantalising glimpses' of the Higgs at the end of last year and this could push their results beyond that threshold.
Why Is It Important?
The origin of mass -- meaning the resistance of an object to being moved -- has been fiercely debated for decades.
Finding the Higgs boson would vindicate the so-called Standard Model of physics, a theory that developed in the early 1970s, which says the Universe is made from 12 particles which provide the building blocks for all matter.
These fundamental particles are divided into a bestiary comprising six leptons and six quarks, which have exotic names such as "strange," "up", "tau" and "charm."
Why Is It Called The Higgs Boson?
The name comes from a British physicist, Peter Higgs, today aged 83, who conceived of a field of mass-conferring particles in 1964 and became the first to publish his idea.
Important theoretical work was also done separately by Belgian physicists Robert Brout, who died in 2011, and Francois Englert, 79.
Bosons are non-matter particles which are force carriers, or messengers that act between matter particles.
The interaction gives rise to three fundamental forces -- the strong force, the weak force and the electromagnatic force. There is a fourth force, gravity, which is suspected to be caused by a still-to-be found boson named the graviton.
How Has The Higgs Been Hunted?
The quest for the Higgs has been carried out at colliders: giant machines that smash particles together and sift through the sub-atomic debris that tumbles out.
The big daddy of these is the Large Hadron Collider (LHC), operated by the European Organisation for Nuclear Research (CERN) in a ring-shaped tunnel deep underground near Geneva.
Smashups generated at the LHC briefly generate temperatures 100,000 times hotter than the Sun, replicating the conditions that occurred just after the Universe's creation in the "Big Bang" nearly 14 billion years ago.
But these concentrations of energy, while violent, occur only at a tiny scale.
On Wednesday, CERN scientists said they had found a new particle that was "consistent" with the Higgs, but further work was needed to determine what it was.
Why "The God Particle"?
The Higgs has become known as the "God particle," the quip being that, like God, it is extremely powerful, exists everywhere but is hard to find.
In fact, the origin of the name is rather less poetic.
It comes from the title of a book by Nobel physicist Leon Lederman whose draft title was "The Goddamn Particle," to describe the frustrations of trying to nail the Higgs.
The title was cut back to "The God Particle" by his publisher, apparently fearful that "Goddamn" could be offensive.
(With inputs from AFP and Reuters)