Quarks and gluons are the only particles which have color charge .
The particles that are built up of quarks, called hadrons, are always color neutral. That
means that although quarks and gluons have a color charge, when they are
in a group, the colors cancel each other so that the particle which they build does not have
a color charge.
There are two ways in which particles with a color charge can be combined to make
a color neutral hadron. Of course, the two resulting hadron groups both have their own
name again. We will first look at the group of hadrons called baryons.
Baryons are built up of three quarks. To get a color neutral baryon (which all baryons are)
each quark has to have a different color. So there must be a red quark, a blue quark and
a green quark. Actually they keep exchanging their colors through gluons so they don't stay
the same color for long, but overall, there will always be a red, a blue, and a green quark.
In the animation on the right you can see the analogy of real colors. When you mix red, green
and blue light you get white light. In the same way, when you have a red and green and a blue
quark, they are color neutral.
Baryons can consist of pretty much any combination of any three quarks. This gives a whole
lot of different baryons with different names. There are, however, only two baryons that
exist naturally in our world: the proton and the neutron. Check out the baryon maker
to make your own baryon and to see its name.
The other group of hadrons ar called mesons. Mesons are built up of a quark and an antiquark .
They have a color and an anticolor which again makes the hadron overall color neutral.
The most important mesons are the pion+ and the pion-, which have the quark combinations
up, anti-down and anti-up, down.