What is a Hadron?

The term hadron is mostly used in particle physics, it is mostly made of quarks, gluons and anti-quarks. A hadron is divided into two families that are known as baryons: made up of 3 quarks and mesons, made up of 1 quark and 1 anti-quark. Just like elephants, quarks exist in groups with other quarks and not found alone. Similarly, hadrons are the composite particles made of quarks. Although individual quarks have functional electric charges, these combine such that hadrons carry a net integer electric charge. Another property of hadrons is that they carry no net color charge even though the quarks carry color charge. Only a very small part of the mass of a hadron is due to the quarks in it, which is the weird thing about hadrons.



The baryons are constructed of three valence quarks. Thus, they are fermions viz. they have odd half-integer spin because they consist of an odd number of quarks. As quarks possess baryon number B = 1/3, the baryon number B = 1. Proton and neutron are the best-known baryons.


Mesons are hadrons that consist of a quark-antiquark pair. They are bosons that should possess some integral spin, i.e., o, 1, or -1 since the number of quarks would be even. Their baryon number B = 0. Instances of mesons that are the by-products of particle physics experiments involve kaons and pions. Pions play a major aspect in possessing atomic nuclei using the residual strong force.

Properties of hadrons:

The properties of hadrons are identified by their valence quarks. For example, a proton is made up of two up quarks, and one down quark. Adding these yields the proton of +1. Hadrons have zero total color charge due to the phenomenon called color confinement. That means hadrons have to be colorless or white. The simple two ways are three quarks of different colors, or a quark of one color and an antiquark that has a corresponding anticolor. Hadrons under the first arrangement are known as baryons and those under the second arrangement are called mesons.

Protons are stable, and neutrons bound within the atomic nuclei are stable of the hadrons, while other hadrons are unstable under ordinary conditions. Hadron physics is studied by colliding protons of heavy elements like that of lead and identifying the debris in the produced particle.

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Practise This Question

A simple pendulum of length 1 m is taken to height h (h = R = radius of the earth) from the earth’s surface.
The time period of small oscillation of the pendulum at that point is (g=π2ms2)