Discovery of the Higgs boson? Done.

Post exam parties may make it difficult to remember much that happened this year, but if you can cast your minds back to December, you may remember a very similar article to this being published. Back in 2011, scientists caught their very first glimpse of the elusive Higgs particle, raising both excitement and skepticism – there was a 1% chance they could be wrong. Now, even the most cynical among us would be hard pressed to argue this one. Scientists are now 99.999943% sure that they have identified a particle perfectly fitting the description of the Higgs.

On July 4th, CERN held a conference confirming that their data on the Higgs particle had reached the 5 sigma level accuracy – the level required to class their findings as a discovery. Scientists are very careful to call this a ‘Higgs-like’ particle – although it fits all of our current theoretical predictions, scientists do not yet know if this is the true standard model Higgs. Whether or not this is exactly what they were looking for, it is an enormous breakthrough. Daniel Scully, a member of Warwick’s Experimental Particle Physics Group said on the day of the CERN conference, “If today’s discovery is the Higgs boson as expected, it will complete our current theory of particle physics and culminate over 40 years of work since it was first proposed as a way of giving particles mass.”

Physicists wrestled with the notion of mass in particle physics, as it is not an intrinsic property of matter on that scale. Peter Higgs, a British physicist proposed the idea of a Higgs Field that interacted with particles to give them mass. However, it is impossible to see a field unless something interacts with it. For example, you cannot see the field of a bar magnet until you put iron filings around it as most matter doesn’t interact with it.

Unfortunately for physicists, if the Higgs field does exist, absolutely everything interacts with it. This also makes it incredibly hard to see. The only observable part of the Higgs Field would be it’s associated particle, the Higgs boson, which manifests itself as a vibration of the field. The task for the Large Hadron Collider (LHC) then was to try and collide particles at high enough energies to disturb the Higgs field. Think of the field as a wall, and the boson as a pebble in the wall. Scratching it with your nail would not get the pebble out, but hitting it with a hammer would. Similarly, a strong enough disturbance of the field would cause the observable vibration that is the Higgs boson.

In December last year, scientists thought they would have to wait at least another year to get to this point. Now, the LCH has brought physicists from a ‘first glimpse’ to a ‘discovery’ in under 7 months for a particle we didn’t even know existed. It’s easy to see that this is a very powerful machine. The question on everyone’s minds is: what next? If it is the Higgs boson, scientists will want to probe further, look at how it decays and interacts with other particles. If it’s not the Higgs boson? Well, either way, the physicists still have plenty of work to do.