Summarizing Quarks

Summary

• Hadrons are thought to be composed of quarks, with baryons having three quarks and mesons having a quark and an antiquark.
• The characteristics of the six quarks and their antiquark counterparts are given in this table, and the quark compositions of certain hadrons are given in this table.
• Indirect evidence for quarks is very strong, explaining all known hadrons and their quantum numbers, such as strangeness, charm, topness, and bottomness.
• Quarks come in six flavors and three colors and occur only in combinations that produce white.
• Fundamental particles have no further substructure, not even a size beyond their de Broglie wavelength.
• There are three types of fundamental particles—leptons, quarks, and carrier particles. Each type is divided into three analogous families as indicated in this figure.

Glossary

bottom

a quark flavor

charm

a quark flavor, which is the counterpart of the strange quark

color

a quark flavor

down

the second-lightest of all quarks

flavors

quark type

fundamental particle

particle with no substructure

quantum chromodynamics

quark theory including color

quark

an elementary particle and a fundamental constituent of matter

strange

the third lightest of all quarks

theory of quark confinement

explains how quarks can exist and yet never be isolated or directly observed

top

a quark flavor

up

the lightest of all quarks