Quarks

Quarks are fundamental particles that serve as the building blocks for hadrons, such as protons and neutrons, which are the components of atomic nuclei. Quarks are a central element in the study of particle physics, and they are described by the theory of quantum chromodynamics (QCD), which is a part of the Standard Model of particle physics.

Properties

Quarks possess several intrinsic properties, including electric charge, mass, color charge, spin, and flavor. Unlike other fundamental particles like electrons, quarks are never found in isolation; they are always confined within composite particles called hadrons due to a phenomenon known as "color confinement." The most familiar hadrons are protons and neutrons, each composed of three quarks.

Types of Quarks

There are six types, or "flavors," of quarks:

• Up
• Down
• Charm
• Strange
• Top
• Bottom

Each flavor of quark comes in three "colors" — red, green, and blue — which are analogous to electrical charges in the way they interact but are related to the strong force.

Interactions

Quarks interact with each other through the strong force, mediated by particles called gluons. The strong force is the most powerful of the four fundamental forces and it acts to hold quarks together in the nucleus of an atom. This interaction is described by quantum chromodynamics (QCD), which is a part of the Standard Model.

Discovery

The existence of quarks was first proposed in 1964 by physicists Murray Gell-Mann and George Zweig, independently. The discovery of the J/psi meson in 1974 provided the first clear evidence of the charm quark, leading to widespread acceptance of the quark model.

In the Standard Model

In the Standard Model of particle physics, quarks are one of the two basic constituents of matter, the other being leptons. The Standard Model explains how the basic building blocks of matter interact, governed by four fundamental forces.

See also

• Particle physics
• Quantum field theory
• Electroweak interaction
• Nuclear force