Difference Between Baryons and Mesons

The key difference between baryons and mesons is that baryons consist of a combination of three quark particles, whereas mesons consist of a pair of quark-antiquark particles.

Baryons and mesons are two types of subatomic particles. Baryons come under fermions and mesons come under bosons. However, both these particles belong to the family of hadrons. These are intermediate mass particles of atoms. All these particles are made of quarks. Quarks are the building blocks that make up all the matter. Therefore, these are elementary particles.

CONTENTS

1. Overview and Key Difference
2. What are Baryons 
3. What are Mesons
4. Side by Side Comparison – Baryons vs Mesons in Tabular Form
5. Summary

What are Baryons?

Baryons are composite subatomic particles that have three quark particles. These particles fall under the category of fermions since these particles have a half-integer spin. Since it has quarks, baryons can participate in strong interactions (strong nuclear force). The most common examples of baryons are protons and neutrons. As these particles have three quarks in them, we can call a baryon as “triquark”. Generally, we consider baryons as massive particles when compared to other subatomic particles. Other examples for these particles include lambda, sigma, xi and omega particles. In addition to the charge and spin number of these particles, we can assign two other quantum numbers as baryon number (B = 1) and strangeness (S). Strangeness is measured in comparison to “strange quarks”.

Baryons make up most of the mass of visible matter. For instance, protons and neutrons are baryons; these two particles are the major components of atoms, and atoms are the smallest unit of all matter. However, electrons are not baryons; they fall under a different family called “leptons”. The difference is that leptons do not interact via strong force.

What are Mesons?

Mesons are hadronic subatomic particles that have a pair of quark and antiquark. Mesons come under the category of bosons. All meson particles are unstable. These particles tend to decay, forming electrons and neutrinos if the meson has a charge. But uncharged mesons undergo decay forming photons. The mesons have an integer spin (baryons have half-integer spin).

The pion is the smallest meson. Mesons can participate in both weak and strong interactions. Moreover, if the meson has a charge, it can participate in electromagnetic interaction as well. We can classify these particles according to the quark content, total angular momentum, parity, etc. Although all mesons are unstable, mesons having a low mass are more stable than massive ones.

What is the Difference Between Baryons and Mesons?

In brief, baryons and mesons are subatomic particles of matter we can classify according to the number of quarks present in them. The key difference between baryons and mesons is that baryons consist of a combination of three quark particles, whereas mesons consist of a pair of quark-antiquark particles.

Moreover, baryons come under the family of fermions because it has half-integer spin. However, mesons come under bosons because it has integer spin. Some examples for baryons include protons and neutrons while for mesons, common examples are photons, electrons and neutrinos.

Below infographic summarizes the difference between baryons and mesons, comparatively.

Summary – Baryons vs Mesons

In summary, baryons and mesons are subatomic particles in matter. The key difference between baryons and mesons is that baryons consist of a combination of three quark particles, whereas mesons consist of a pair of quark-antiquark particles.

Reference:

1. “Baryon.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 3 Oct. 2011, Available here.
2. “Mesons.” Hadrons, Baryons, Mesons, Available here.

Image Courtesy:

1. “Quark structure omega” By Matgoth – Derivate of Image:Quark structure neutron.svg (CC BY-SA 3.0) via Commons Wikimedia
2. “Bosons-Hadrons-Fermions-RGB-png2” By Hugo Spinelli – Own work (CC0) via Commons Wikimedia