Introduction

Fermions vs Bosons

Fermions are particles that obey the Pauli exclusion principle – two fermions cannot occupy the same quantum state. This means that two fermions cannot be in the same place at the same time. They usually include particles of matter, and they have half-integer spin.

Bosons, in contrast, can occupy the same place. They have integer spin. Most bosons are force carriers of different forces.

Spin

Spin is a property of subatomic particles; think of it as an intrinsic property, like mass or charge. While fermions have half-integer spin, bosons have integer spins. For example:

  • All leptons and quarks can have a spin of plus or minus one-half.
  • Photons, gluons, and W-, W+, and Z bosons have a spin of one.
  • The proposed graviton has a spin of 2.
  • The Higgs Boson has a spin of 0.

Types of Bosons

Fundamental forces

Gauge bosons are those that carry any of the four fundamental forces:

  • The electromagnetic force is carried by bosons named photons. This force is responsible for the attraction/repulsion of positive and negative charges. However, its effects are small over large distances, as large obejcts are usually neutral when + and - charges cancel.

  • The strong force is carried by gluons. It is the strongest force, as it binds protons and neutrons together, as well as quarks to form protons and neutrons, in spite of electromagnetic repulsion. It has a very small range, though.

  • The weak force is carried by W-, W+, and Z bosons. It is responsible for radiactive decay.

  • Gravity is proposed to be carried by the graviton. Although gravity is the weakest of the four fundamental forces, it has the largest effect over large distances, as it always adds up for massive objects.

Higgs Boson

The Higgs Boson mediates the Higgs field, which causese objects to have mass. Its existence was confirmed by CERN’s Large Hadron Collider (LHC) in 2012. In December 2013, Peter Higgs and Francois Englert were awarded the Noble Prize in Physics for predicting its existence.

Types of Fermions

Quarks

Three quarks make up a hadron (protons and neutrons). They are bound together by the strong force. There are six kinds of quarks. They have fractional charges such as +2/3 and -1/3.

  • A proton is made of one two up quarks and one down quark.
  • A neutron is made of one up quark and two down quarks.

Generations

There are three “generations” of quarks; each column in the table above is a new generation. Each generation is similar to the previous one, except for that it has a lot more mass. The first generation is made of up and down quarks, which make up more common matter such as protons and neutrons. The other quarks, however, are more unstable and are less common.

Leptons

Like quarks, there are three generations of leptons. The first-generation leptons, electrons, are a lot more common than the others.

Charged leptons include the electron, muon, and tauon. Each has a charge of -1.

Neutral leptons, also known as neutrinos, also have three generations – electron, muon, and tau neutrinos.

Sources