What is the Higgs boson?

The mathematical model which describes how the fundamental forces of nature interact with elementary particles is known as the ‘standard model’. Although this model has been extremely successful, there are a number of outstanding problems with it. Probably the biggest is why some particles like the photon have no mass, while others are very heavy indeed. In the mid-Sixties, British physicist Professor Peter Higgs came up with a solution and suggested that a special type of field – a bit like a magnetic field – exists across the whole universe. Some particles feel the effect of this field very strongly (a bit like how iron feels a magnetic field) and get a large mass, while other particles only feel the effect of this field slightly (light particles) or, in the case of a photon, not at all.

Although the mathematics of this theory seem to solve the problem, the standard model requires that any type of field must have a particle, called a ‘boson’, associated with it. This particle is now known as the Higgs boson. If Peter Higgs’ theory is correct, the Higgs boson must exist and the Large Hadron Collider at CERN will find it. Such a discovery would be a great achievement for the standard model and our understanding of how the universe works.

Update 13 Dec 2011: Today it has been announced that hints of the Higgs boson have been discovered at the LHC at CERN. Although more data will be needed to announced it as a formal discovery, which will probably occur at some point in 2012, it seems more than likely that this basic building block of the universe has finally been found.

Answered by Dr David Evans, a reader in high-energy physics at the University of Birmingham who leads the UK team working on the ALICE experiment at the CERN LHC. ALICE aims to create and study a primordial state of matter known as a quark-gluon plasma.

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