Summarizing Particles, Patterns, and Conservation Laws

Summary

• All particles of matter have an antimatter counterpart that has the opposite charge and certain other quantum numbers as seen in this table. These matter-antimatter pairs are otherwise very similar but will annihilate when brought together. Known particles can be divided into three major groups—leptons, hadrons, and carrier particles (gauge bosons).
• Leptons do not feel the strong nuclear force and are further divided into three groups—electron family designated by electron family number ; muon family designated by muon family number ; and tau family designated by tau family number . The family numbers are not universally conserved due to neutrino oscillations.
• Hadrons are particles that feel the strong nuclear force and are divided into baryons, with the baryon family number being conserved, and mesons.

Glossary

boson

particle with zero or an integer value of intrinsic spin

baryons

hadrons that always decay to another baryon

baryon number

a conserved physical quantity that is zero for mesons and leptons and \(±1\) for baryons and antibaryons, respectively

conservation of total baryon number

a general rule based on the observation that the total number of nucleons was always conserved in nuclear reactions and decays

conservation of total electron family number

a general rule stating that the total electron family number stays the same through an interaction

conservation of total muon family number

a general rule stating that the total muon family number stays the same through an interaction

electron family number

the number \(±1\) that is assigned to all members of the electron family, or the number 0 that is assigned to all particles not in the electron family

fermion

particle with a half-integer value of intrinsic spin

gauge boson

particle that carries one of the four forces

hadrons

particles that feel the strong nuclear force

leptons

particles that do not feel the strong nuclear force

meson

hadrons that can decay to leptons and leave no hadrons

muon family number

the number \(±1\) that is assigned to all members of the muon family, or the number 0 that is assigned to all particles not in the muon family

strangeness

a physical quantity assigned to various particles based on decay systematics

tau family number

the number \(±1\) that is assigned to all members of the tau family, or the number 0 that is assigned to all particles not in the tau family