-Samikshya Kar
In the previous article, we looked into the general aspects of the SMPP. For this part, let’s go to the composition of the model.
The history of the elementary particles in the SMPP dates back to 1897 when J. J. Thomson discovered the first constituent particle of the model, the electron. But the modern form of the theory was established in the late 1960s as mentioned in the previous article. The last constituent particle of the current model, the Higgs Boson was discovered in 2012.
Now, let’s go with the classification of the particles first. The Standard model is broadly divided into two classes of fundamental particles: The Fermions and the Bosons. A very plain example can be given here to explain the functions of these two classes. If matter is compared to a normal building house, then the fermions act as the bricks giving the structure while the bosons act as the cement mixture holding the bricks together i.e. the Fermions on one hand give structure to the atoms of a substance whereas the Bosons mediate the interaction force between the Fermions holding them together.
The Fermions are further divided into two classes: The Leptons and the Quarks. Both the leptons and quarks are six in number.
In our high school times, whenever the structure of the atom is discussed, it is always said that matter is composed of electrons, protons and neutrons. Have you ever wondered why protons and neutrons are so heavy as compared to electrons? That is because the proton or the neutron is not a fundamental particle as it is composed of three quarks.
| FERMIONS | BOSONS |
|---|---|
| Named after a Scientist named Enrico Fermi and follows Fermi-Dirac statistics. | Named after a Scientist named Satyendra Nath Bose and follows Bose-Einstein statistics. |
| There are twelve elementary fermions in the SMPP. | There are five elementary Bosons in the SMPP. |
| They follow Pauli exclusion principle i.e. one fermion can occupy one single state at one time. | They don’t follow Pauli exclusion principle i.e. more than one boson can occupy one single state at one time. |
| Fermions are further divided into Leptons and quarks. | Bosons can be scalar or vector bosons. |
| Each of the fermions has one antiparticle of its own. | Bosons are their own antiparticles. |
Composite fermions are known as Baryons. |
Composite bosons are known as Mesons. |
The quarks build some composite particles called as the hadrons. Though hadrons are not included in the SMPP, we will discuss them towards the end of the series because as we can see the group includes some very crucial particles like protons and neutrons.
Well, the last paragraph was a short trailer of our next article because I will take you to the domain of fermions where we will get to know about all the members of the lepton and quark family, the experiments or coincidences in the history of science that led to the discovery of them and their properties. We will get into the details of the Boson particles later.
Till then, Sayonara! :)
Written By-
Samikshya Kar
