Classes of Particles

Fundamental particles that come in six types, including three charged particles and three nearly massless, neutral neutrinos.

Were an early concept describing the internal structure of hadrons before quarks were accepted. They are now understood to have been quarks, so the term is mostly historical.

Negative charge discovered by Thomson

Integer spin and are not restricted by the Pauli Exclusion Principle, allowing them to share quantum states. Composite particles can be bosons if their total spin is integral.

Positive charge discovered by Rutherford

Half-integer spin and are subject to the Pauli Exclusion Principle, meaning no two can occupy the same quantum state. Their name honors physicist Enrico Fermi.

Carry the strong nuclear force and bind quarks together inside hadrons. They are massless, uncharged, and possess color.

Particles made of quarks and affected by the strong nuclear force, mainly baryons and mesons and are colorless

Usually measured in MeV using Einstein’s equation E = mc^2 which converts energy into mass. Particle charges are expressed in units of the fundamental electric charge.

Fundamental particles that carry the forces of nature, such as photons for electromagnetism and gluons for the strong force. Each force is mediated by its own type of gauge boson.

Neutral Charge discovered by Chadwick

Fundamental fermions that come in six flavors with fractional electric charges and combine to form mesons and baryons. The discovery of the very massive top quark confirmed a key prediction of the Standard Model.

Composite fermions made of three quarks, such as protons and neutrons. Each baryon must contain one quark of each color so that it is colorless overall.

Composite bosons made of a quark and an antiquark and are always colorless. More complex combinations like tetraquarks exist but are rare.