The Standard Model of Particle Physics and the Higgs Field: What are they exactly?

by Sparshita Dey

The Higgs boson theory is a theory based on the Standard Model of Particle Physics – a model of the fundamental particles which make up the universe and a model capable of explaining all physics as we know it today! As for the recently discovered Higgs boson particle, physicists have been expecting its discovery since Peter Higgs proposed its existence in 1964. Since then, it has been a major part of all physics, equations and ideas even though it had not been discovered until this year when CERN’s hadron colliders proved the existence of these fascinating, fundamental boson particles.

The Standard Model of Particle Physics

Scientists have been familiar with electrons (discovered by J.J. Thompson) since 1987, protons (discovered by Ernest Rutherford) since 1919 and neutrons (James Chadwick) since 1932. The knowledge of all atoms making up all the matter in the universe led to the thought of a more simplistic universe being created from the three sub-atomic particles. However, soon after 1932, other particles started being discovered. These particles were more fundamental particles discovered too in the early 20^th century through cosmic rays. The particles were given random names and were not immediately classified and coordinated into groups like in the more familiarised periodic table. However later, they were finally grouped based on the properties: spin, mass, life time and electrical charge.

These new fundamental building blocks called leptons and quarks are the main two families of particles which make up all of the matter existing today. Quarks for example also make up protons and neutrons as discovered; however just like atoms in a compound bond ionically or covalently to each other to form the more complicated substance, the Standard Model was also devised to involve the forces or the “force carriers” which bonds the various leptons and quarks together.  Therefore, the force carriers bonding the different particles together are called bosons; the Higgs boson particle therefore belonging to this family.

>The Standard Model of Particle Physics before the Higgs boson

There are thought to be six types of leptons and quarks each so far (as shown by the diagram to the left) and 6 types of bosons (the five shown and also the all-important Higgs boson ofcourse! The different types of boson are responsible for different properties. The W^+/- and the Z⁰ bosons for example carry the weak forces (i.e. responsible for nuclear fission – radioactive decay – and fusion like in stars). The photon carries the electromagnetic force (so any fermion – general name for leptons or quarks – with a charge will have an electromagnetic interaction) whereas the gluons or the “strong attractions” only act on the quarks for example almost gluing the quarks together to create the protons and neutrons in an atomic nucleus and keeping the nucleus together as well.

The Higgs Field and the Higgs Boson: what exactly are they?

The final boson particle, which has been until this year just a theory, is the Higgs boson particle. From what I understand of it, it could be pretty similar to the photon and its relation to the electromagnetic force but replacing the photon with a Higgs boson particle and the electromagnetic field with a Higgs field. In terms of what exactly the Higgs boson particle is or what the Higgs field is, in simple terms we can say that it is a medium (or essentially a field) which gives objects or particles with the ability to interact with it, a mass. So a particle which interacts with it more (or “bends” it more) will have a greater mass than an object which passes straight through it without having much effect or any on the Higgs field – in which case no interaction with the field will mean the object or particle has no mass. The Higgs field is therefore created by individual Higgs bosons carrying this “force”. 

>Replacing spacetime with the Higgs field, this diagram shows how the Higgs field can be “bent” when an object with mass interacts with it 

To simplify this concept further, we could use a good analogy (also used by the theoretical physicist, John Ellis) to explain the complicated idea. Imagine an empty field of snow completely covering the entire region in front of you in a very thick, white blanket. We all know that this deep sea of snow is made up of several much smaller components: snowflakes (lets ignore the atoms and individual elements or sub atomic particles at the moment!). The deep snow field is like the Higgs field whereas the snowflakes are the individual Higgs bosons. Now imagine you skiing through this deep layer of snow. When you are skiing through the snow, your large surface area in contact with the snow and higher speed means that you do not really have much of an effect on the snow below you. Similarly if we considered you as an object in the Higgs field, you would be travelling at a high speed through the medium without affecting it very much so your mass would be quite negligible or even 0 – like an object in space travelling at the speed of light with no mass. However, in comparison if you were wearing normal shoes in the deep snow, you would sink into the snow by a lot and would be a lot slower than the skier so therefore would be having an effect on the snowy field. If this were the Higgs field and you were the object, then you would be “bending” the Higgs field this time by a lot, therefore your mass would have been great and you would have been travelling at a speed much below the cosmic speed limit.

>Peter Higgs

The Genius Proposition: Peter Higgs

“I certainly had no idea it would happen in my lifetime at the beginning, more than 40 years ago. I think it shows amazing dedication by the young people involved with these colossal collaborations to persist in this way, on what is a really a very difficult task. I congratulate them.” - Peter Higgs (July 4th 2012)

Peter Higgs in 1964 proposed that there was an energy field that permeated the entire universe: the Higgs field as we call it today. He proposed the theory to explain how different subatomic particles had different masses: e.g. addressing questions like why are muons more massive than electrons? Etc. His idea was that any particle in contact with the Higgs field which has the ability to interact with it or bend it rather than pass straight through it has a mass. So essentially, the discovery and the proof that the Higgs boson particle exists proves physics as we know it and proves that objects have a mass due to their interaction with the field generated by the particles. The reason that this has a broader significance is because of the idea of spacetime, the basis of so many theories including Einstein’s theory of general relativity (E=mc²) which itself revolutionised science.

The very close similarities between the two lead me to think that they are the same concept: perhaps the Higgs field is just the more improved and specific substitution to spacetime? In this case, the proof for the Higgs boson particle being a fundamental boson particle could be the ultimate proof that humans are on the right path with science (especially as it helps to explain so many other theories as well) and that we are getting closer to discovering much, much more in the future. This is why I find the world of mathematics and science simply beautiful!

So what do you think of the new discovery of the Higgs boson particle? Do you feel that it has or will make much of an impact on science or particularly particle physics? Or does it make you question other ideas? Please leave your ideas and comments!