The Quarks

All quarks have mass and this increases with generation. Each generation contains two quarks with fractional charge, one with $\frac{2}{3}$e and the other $-\frac{1}{3}$e. The quarks are called; up, down, strange, charm, bottom and top. All these quarks also have an anti-particle of the same mass, but opposite quantum numbers. The up quark is the lightest quark with a mass of 1.5 - 5 MeV, whereas the top quark is the heaviest, with a mass up to 100,000 times greater than the up quark at about 170 GeV. For a full description of the quark, as well as the lepton properties see [5].

Quarks are never observed in isolation. They are always found in bound states with other quarks. The composites of quarks are called hadrons. Quarks have the quantum number of colour and may take one of three colour charges, red, blue or green (or the corresponding anti-red, anti-blue and anti-green for the anti-particles). The bound states of quarks must be colourless objects, and so hadrons can come in two types, fermionic baryons comprised of three quarks or three anti-quarks, one of each colour, and bosonic mesons comprised of a quark and an anti-quark, one with colour and the other with the anti of this colour. Both baryons and mesons will always have integer charge. The most well known baryons are the proton, which is a uud bound state, and the neutron, which is a udd bound state.

A summary of the properties and basic quantum numbers of all the fermions is shown in table 1.1.

Table 1.1: The properties and basic quantum numbers of the fermions. t$_{3}$ is the weak isospin of the particle, which is the quantum number for the weak force. The quantum numbers for the corresponding anti-particles are obtained by taking the negative of the numbers given in the table.

Fermion	Gen.	Flavour	Mass (MeV)	Charge (Q)	(t$_{3}$)$_{\rm L}$	Colour Charge
		e	0.51	$-$1	$-\frac{1}{2}$	0
				$\nu_{e}$	0	0	$+\frac{1}{2}$
			$\mu$	105.7	$-$1	$-\frac{1}{2}$	0
				$\nu_{\mu}$	0	0	$+\frac{1}{2}$
			$\tau$	1777	$-$1	$-\frac{1}{2}$	0
				$\nu_{\tau}$	0	0	$+\frac{1}{2}$
		u	1.5-5	$+\frac{2}{3}$	$+\frac{1}{2}$	R,G,B
				d	17-27	$-\frac{1}{3}$	$-\frac{1}{2}$
			s	60-170	$+\frac{2}{3}$	$+\frac{1}{2}$	R,G,B
				c	1100-1400	$-\frac{1}{3}$	$-\frac{1}{2}$
			b	4100-4400	$+\frac{2}{3}$	$+\frac{1}{2}$	R,G,B
				t	173800	$-\frac{1}{3}$	$-\frac{1}{2}$