3. The quark family

Quarks are one of the two families of matter particles. They are assumed to be point like and without internal structure. There are six of them and they have the names up, down, charm, strange, top bottom. They are grouped in pairs according to their charge and mass. The pairs are known as generations.

Note: The masses shown in the tables are approximate.

Charge in units of electron charge

First generation

Second generation

Third generation

+2/3

3 MeV

charm

1.3GeV

top

175 GeV

-1/3

down

6 MeV

strange

125 MeV

bottom

4.1 GeV

Quarks are fermions and respond to electromagnetic, weak, and strong interactions. Like all fermions, quarks have a half-integral spin. In quantum-mechanical terms, spin constitutes the property of intrinsic angular momentum. Quarks obey the Pauli exclusion principle, which prohibits any two identical fermions in a given population from occupying the same quantum state.

Quarks carry fractional charge. Each of the quarks has a corresponding antiparticle. The masses of the members of the antiquark family are identical to that of the members of the corresponding quark family, but all of the other properties are reversed.

The antiquarks are:

Charge in units of electron charge

First generation

Second generation

Third generation

-2/3

antiup