The key difference between fundamental particles and elementary particles is that fundamental particles are fundamental constituents of matter whereas elementary particles are the smallest known building blocks of the universe.
We often use the names fundamental particles and elementary particles as synonyms. But there is a difference between fundamental particles and elementary particles because the term fundamental particle is used mainly for quarks while the term elementary particle is used for all smallest known particles.
CONTENTS
1. Overview and Key Difference
2. What are Fundamental Particles
3. What are Elementary Particles
4. Side by Side Comparison – Fundamental Particles vs Elementary Particles in Tabular Form
5. Summary
What are Fundamental Particles?
Fundamental particles or quarks are a major category of elementary particles and are a fundamental constituent of matter. Generally, these particles interact strongly with each other by strong nuclear interaction to form combinations of quarks. We can call these combinations as Hadrons. However, isolated quarks do not exist in our universe at present. Therefore, it is reasonable to say that all the quarks in this universe are in some form of hadrons. (Most common and known types of the hadrons are protons and neutrons).
Figure 01: Quarks
Furthermore, quark particles have an internal property named as the baryon number. All these particles have a baryon number of 1/3, and anti-quarks have baryon numbers -1/3. Moreover, in a reaction involving elementary particles, this property is known as the baryon number is conserved.
In addition to these, quark particles have another property named as the flavour. There is a number that is assigned to denote the flavour of the particle known as the flavour number. The flavours are referred to as Upness (U), Downness (D), Strangeness (S) and so on. The up quark has an upness of +1 while 0 strangeness and Downness.
What are Elementary Particles?
Elementary particles are subatomic particles that have no substructure. This means these particles cannot be divided further into other particles. The major elementary particles include fermions (which come in two types as matter and antimatter particles) and bosons. If there is a particle that contains two or more elementary particles, we can call them as composite particles. All elementary particles are either bosons or fermions.
Figure 2: Elementary Particles
Bosons are a type of elementary particles having an integer spin. These particles are not constrained by the Pauli exclusion principle. Furthermore, we can describe the energy distribution of boson particles using Bose-Einstein statistics.
Fermions are another type of elementary particles containing a half-integer spin. Therefore, these particles are constrained by the Pauli Exclusion Principle. Unlike bosons, two fermions cannot occupy the same quantum state at the same time. If multiple fermions have the same spatial probability distribution, then at least the spin of each fermion is different from each other. Moreover, fermions are particles that make up the matter.
What is the Difference Between Fundamental Particles and Elementary Particles?
The key difference between fundamental particles and elementary particles is that fundamental particles are quarks or fundamental constituents of matter whereas elementary particles are the smallest known building blocks of the universe. Fundamental particles are quarks while elementary particles are either bosons or fermions.
Moreover, fundamental particles have a color charge while elementary particles may or may not have a color charge. So, this is another difference between fundamental particles and elementary particles.
Below infographic compares both particles side by side to discern the difference between fundamental particles and elementary particles easily.
Summary – Fundamental Particles vs Elementary Particles
Although we often use the names fundamental particles and elementary particles as synonyms, there is a difference between fundamental particles and elementary particles. The key difference between fundamental particles and elementary particles is that fundamental particles are quarks which are a fundamental constituent of matter whereas elementary particles are the smallest known building blocks of the universe.
Reference:
1. “Quark.” Wikipedia, Wikimedia Foundation, 10 Aug. 2020, Available here.
Image Courtesy:
1. “Proton quark structure” By Jacek rybak – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Standard Model of Elementary Particles” By MissMJ, Cush – Own work by uploader, PBS NOVA [1], Fermilab, Office of Science, United States Department of Energy, Particle Data Group (Public Domain) via Commons Wikimedia