I know about electrons, protons and neutrons. What are the other subatomic particles, and what is their role?

In fact, neutrons and prototons are composite particles. A proton is composed of two “up”, and one “down” quarks. A neutron is composed of two “down”, and one “up”, quark. There are many other combinations of quarks, their antiparticles, that are possible. However they are unstable and only last a very short time. The pion is one example of such a combination. There are many types of pions: an up and antidown quark, a down and antiup quark, or an up-antiup and down-antidown couple. Pions act as force carriers. They hold together neutrons, and especially protons, within an atom, despite the immense electrostatic force that would push them apart.

At the most basic level there is the electron, the up and down quiark and the muon. These particles are the basis of all matter. This pattern is repeated two more times. There is the muon, which is a heavier electron, the strange quark and charm quark, as well as the tau particle, which is an even heavier version the electron, the top quark and bottom quark. These particles, which are extremely heavy and only live for a short time, can be detected by particle accelerators.

Quarks in a particle such as the proton are held together with particles called gluons. Photons are responsible for electromagnetism. There is also the weak interactions with two heavy force carriers particles, the W- and Z-bosons. The weak interaction is responsible both for some forms of nuclear decay as well as for the transformation of neutrons into protons. The weak interaction produces neutrinos which are similar to electrons but without electricity. These neutrinos are very light particles that almost never interact with matter. Most neutrinos that reach Earth travel through the Earth as though it were not there. Neutrinos, like electrons, also have heavier counterparts. There is the electron neutrino (the muon neutrino) and the tau neutrino (the tau neutrino).

The Higgs boson is last, which plays an important role in the W-, Z-, and electrons’ mass formations.

Wikipedia has a great diagram that includes all of these elementary particles.

In addition to this diagram, there is the hypothetical graviton (which would be responsible for mediating gravity; however, developing a quantum theory of gravity remains one of the major challenges in theoretical physics); and another hypothetical particle, the axion, which may resolve certain problems in the Standard Model of particle physics and may also be a candidate for the infamous “dark matter” content in the universe.

Finally, there are more speculation theories that predict whole new zoos full of particles. Supersymmetry, for example, predicts that each of these particles will have a supersymmetrical partner. However, such particles have never been seen in particle accelerator experiments.


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