Scientists believe they have discovered the elusive Higgs boson, or “God particle”. Data from CERN’s Large Hadron Collider (LHC), which last July was tentatively thought to indicate the existence of the Higgs boson, has now been further analysed with much more positive results.
Yesterday, the Atlas and CMS collaborations of the LHC presented preliminary new results that further elucidate the particle discovered last year.
Having analysed two and a half times more data than was available for the discovery announcement in July, they find that the new particle is looking more and more like a Higgs boson – the particle linked to the mechanism that gives mass to elementary particles.
“The preliminary results with the full 2012 data set are magnificent and 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,” says CMS spokesperson Joe Incandela.
“The beautiful new results represent a huge effort by many dedicated people. They point to the new particle having the spin-parity of a Higgs boson as in the Standard Model. We are now well started on the measurement programme in the Higgs sector,” says Atlas spokesperson, Dave Charlton.
Scientists are now pondering whether this is the Higgs boson of the Standard Model of particle physics, or possibly the lightest of several bosons predicted in some theories that go beyond the Standard Model. Finding the answer to this question will take time.
What is the Higgs boson?
In the 1970s, physicists realised that there are very close ties between two of the four fundamental forces – the weak force and the electromagnetic force. The two forces can be described within the same theory, which forms the basis of the Standard Model.
This “unification” implies that electricity, magnetism, light and some types of radioactivity are all manifestations of a single underlying force known as the electroweak force.
It is thought that, just after the big bang, the Higgs field was zero, but as the universe cooled and the temperature fell below a critical value, the field grew spontaneously so that any particle interacting with it acquired a mass.
The more a particle interacts with this field, the heavier it is. Particles like the photon that do not interact with it are left with no mass at all. Like all fundamental fields, the Higgs field has an associated particle – the Higgs boson. The Higgs boson is the visible manifestation of the Higgs field, rather like a wave at the surface of the sea.
A problem for many years has been that no experiment has observed the Higgs boson to confirm the theory. On 4 July 2012, the Atlas and CMS experiments at the LHC announced they had each observed a new particle in the mass region around 126 GeV.
This particle is consistent with the Higgs boson but it will take further work to determine whether or not it is the Higgs boson predicted by the Standard Model.