Defining Quarks: The Building Blocks of Hadrons
A quark is an elementary particle and a fundamental constituent of matter. These tiny particles combine to form composite particles called hadrons, the most well-known examples of which are protons and neutrons, which make up the nuclei of atoms.
Flavors, Colors, and Fractional Charges
There are six distinct types, or 'flavors,' of quarks: up, down, charm, strange, top, and bottom. Each flavor also possesses one of three 'colors' (red, green, or blue), a property related to the strong nuclear force. Unlike electrons, quarks carry fractional electric charges, such as +2/3 or -1/3 of the elementary charge.
Quarks in Protons and Neutrons
To illustrate, a proton is composed of two 'up' quarks and one 'down' quark (often denoted as uud). Conversely, a neutron consists of one 'up' quark and two 'down' quarks (udd). These combinations result in the net integer charge observed for these subatomic particles (+1 for a proton, 0 for a neutron).
Importance in the Standard Model
Understanding quarks is essential for comprehending the strong nuclear force, which binds them together, and for describing the Standard Model of particle physics. This model details the fundamental particles and forces that govern the universe, with quarks being central to its explanation of matter.