Elementary Particles

Fermions and Bosons

Hadrons

• A hadron is a subatomic composite particle made up of two or more quarks that are held together by the strong nuclear force (these are protons and neutrons!)

Quarks

• A proton is comprised of 2 up quarks and 1 down quark. The up quark has a charge of $+\frac{2}{3}$ and a down quark has a charge of$-\frac{1}{3}$ summing these up we get a value of $+\frac{3}{3}$ or +1.
• A neutron is comprised of 1 up quark and 2 down quarks. Summing these up we get a value of 0
• Quarks are never found by themselves they are either in pairs or in triplets
• They have various intrinsic properties which include charge, spin, mass, and even colour
• These quarks were discovered by high energy particle accelerators that smash together protons, neutrons, electrons, and positrons
• These experiments are known as deep inelastic scattering which is an extension of Rutherford's scattering experiment except at much higher energies
• These experiments showed the existence of quarks that were only mathematically hypothesized due to the need to fulfill the conservation of mass, energy, momentum,
• They were discovered due to the requirement of the laws of physics, namely the conservation of momentum, charge, mass (and energy), among others