The smallest particle in the world is a tie between quarks and leptons. Quarks are the fundamental particles that make neutrons and protons in atoms. There are several different classifications of quarks based on their properties that break down into up, down, charm, top and bottom; I don’t make up the names, I just tell you what they are J Most quarks disappeared in the microseconds after the Big Bang, but can be recreated under certain conditions. Up and Down quarks are common and combine with two of their brethren to form either a neutron or a proton. A proton is made up of 2 Up and 1 Down quark with a net result of a 1 positive charge. Neutrons are made of 2 Down quarks and 1 Up quark and have a net charge of zero. The math doesn’t seem to add up, but I am sure there is some very complicated, quantum physics way of explaining why the different combinations of Up and Down yield either a proton or a neutron.
Leptons are more complicated to explain and I will do my best. Leptons are the other component particle to make up an atom. Leptons come in 6 flavors: electrons, muons, and the tau. The other three are these particles combined with their associated neutrino: electron neutrino, them muon neutrino and the tau neutrino. Neutrinos have very little mass and almost no charge and result from nuclear fusion and beta decay. Beta decay produces electron neutrinos and happens when neutrons change to protons or vice versa. The human body is penetrated by quadrillions of neutrinos every second and most come from our Sun.