One of my previous blog posts explains quarks. If you haven’t heard of a quark read it here before continuing.
I just have a little more to add to my previous blog post about quarks. The above image shows the different generations of quarks, the third generation is the heaviest and the first generation is the lightest. Second and third generation quarks can only be created during high energy collisions such as those that occur inside particle colliders. When second and third generation quarks are created they quickly decay into other particles that are more stable. Every particle has an antiparticle which has the same properties as the original particle but the opposite electric charge and this applies to quarks too. Antiparticles are denoted by an overbar above the letter.
Quarks are never seen in isolation as they are held together by an extremely strong force which was named appropriately as the strong force. Hadrons are any particles that are made up from quarks and these fall into the three categories below:
Protons and neutrons are an example of baryons and these are the only naturally occurring hadrons on Earth. Some antibaryons and mesons can be created in high energy collisions but as before, they decay rapidly into more stable particles.
These are the only possible types of baryons for one reason. The electric charge of the hadron is the sum of all the electric charges of the quarks that it is composed of. In the first diagram you can see that quarks do not have integer charges, they are either +2/3e or -1/3e and -2/3e or +1/3e for the antiquarks.
The charge of a hadron always has to be a integer and therefore no other combinations of hadrons can be made other than the three stated above.