As mentioned in my post about the standard model of physics (which can be found here), one of the most important recent discoveries in particle physics is the Higgs boson particle discovered on 4th July 2012 – and as promised, here is its very own post!If you have even the smallest of interests in physics, then you have probably heard of the Higgs boson. So, what is it? Why is it so important?
Back in the 1960’s, theoretical physicists noticed that two of the four fundamental forces, the weak and electromagnetic, were very similar. Similar in such a way that they can be described by the same theory. This implies that light, consisting of electricity and magnetism, and some types of radioactivity all stem from one force called the electroweak force. By uniting these forces into one, the new unified theory’s basic equations correctly describe the combined electroweak force.
Remembering that each force has an accompanying force carrier particle, a boson, then if the unified theory correctly describes the electroweak force to a basic level, that means it should also be able to correctly describe the force carriers. And it does. Except for one big problem – all of the force carrier particles come out of the theory with no mass! None!
The boson for the electromagnetic force is the photon which is indeed massless. The problem arises from the weak force carriers, the W and Z bosons, as these are known and found particles which have a finite mass.
Now you see the problem.
Theorists Robert Brout, Franҫois Englert and Peter Higgs attempted to solve this problem with a proposal that would account for the mass. This was that the entire universe is filled with an invisible field, now known as the ‘Higgs field’, which gives the mass to particles when they interact with it. Particles that interact more with the field acquire more mass and particles that don’t interact with it at all are left massless, just like the photon. This is called the Brout – Englert – Higgs mechanism.
With every fundamental field there is an associated particle, just like the photon is to the electromagnetic field, so to prove this proposal they had to detect the associated particle to the Higgs field – the Higgs boson.
A great analogy for this concept is water. Water in a swimming pool fills all the space, but water is made of millions and millions of H2O molecules, just like the Higgs field is made up of loads of Higgs boson particles. Some fish swim through the water quickly and easily, barely interacting with the water at all, like the photons. On the other hand, if I was in the water doing my attempt at swimming (I can’t swim), I would be interacting with the water a lot more than the fish and moving a lot slower. In this analogy I would be a massive particle made massive by interacting a lot with the water similar to the W and Z bosons.
If this proposal was correct, agreeing to experimental data, it would vastly contribute to the understanding of particle physics on a subatomic level and explain how the particles, hence us and everything in our universe, have mass.
On 4th July 2012, ATLAS and CMS experiments at CERN’s Large Hadron Collider announced that they had detected a particle that was consistent with the predictions of the standard model for the Higgs boson. After more data was taken and analysed, it was indeed found to be the Higgs boson creating strong evidence for the Brout – Englert – Higgs mechanism.
On 8th October 2013, more than 50 years after the theory was proposed, Peter Higgs and Franҫois Englert (Robert Bruot had sadly passed away) were jointly awarded the Nobel prize in Physics “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted particle by the ATLAS and CMS experiments at CERNs LHC.”
A massive accomplishment for particle physics.
A great video from Fermilab:https://youtu.be/RIg1Vh7uPyw