03/07/2012 18:22 BST

The God Particle: What Is Higgs Boson And Why So Much Fuss?

The Higgs Boson – or God particle – was named after Edinburgh University’s Professor Peter Higgs, who predicted it to fill in a gap in scientists’ understanding of the universe.

But it wasn’t just any old gap – it was bafflement at why, to put it simply, matter exists at all.

What physicist couldn’t grasp was why elementary particles have mass.

The Standard Model theory explained what they were and how they interacted with each other, but couldn’t answer this one basic question.

Without mass, there would be no atoms, no chemistry, no biology, no people – and everything would fly around at the speed of light.

Just what was it that slowed everything down and allowed particles to form structures?

Cue the Higgs boson.

It was discovered – or at least theorised – by Peter Higgs and several other scientists in the 1960s.

The mechanism they described would allow particles to have masses.

This is now known as the Higgs mechanism.

According to theory, the Higgs mechanism works as a medium that exists everywhere in space. Particles gain mass by interacting with this medium.

Peter Higgs pointed out that the mechanism required the existence of an unseen particle, which we now call the Higgs boson.

The Higgs boson is the fundamental component of the Higgs medium, much as the photon is the fundamental component of light.

The Higgs boson is the only particle predicted by the Standard Model that has not yet been seen by experiments.

The Higgs mechanism does not predict the mass of the Higgs boson itself but rather a range of masses.

Fortunately, the Higgs boson would leave a unique particle footprint depending on its mass. So scientists know what to look for and would be able to calculate its mass from the particles they saw in the detector.

Experimentalists might find that the Higgs boson is different from the simplest version the Standard Model predicts.

Many theories that describe physics beyond the Standard Model, such as supersymmetry and composite models, suggest the existence of a zoo of new particles, including different kinds of Higgs bosons.

If any of these scenarios turn out to be true, finding the Higgs boson could be a gateway to discovering new physics, such as superparticles or dark matter.

On the other hand, finding no Higgs boson at the LHC would give credence to another class of theories that explain the Higgs mechanism in different ways.