Color conservation in gluon fragmentation

[Manojg]

Hi,

When a gluon fragments to a quark anti-quark pair (c c_bar for an example), how is color conserved? Gluon is colored but c c_bar pair is colorless.

Thanks.

 

[Bill_K]

Gluons carry both a color and an anticolor. A gluon that was red anti-green for example could fragment into a red quark and a green antiquark.

 

[kaksmet]

Gluons carry both a color and an anticolor. A gluon that was red anti-green for example could fragment into a red quark and a green antiquark.

which, since they have different color/anticolor does not form a color neutral state.

 

[Vanadium 50]

When the q-qbar pair fragments to hadrons, there will be a color connection to the other colored objects in the hadron that contained the original gluon.

 

[Manojg]

Gluons carry both a color and an anticolor. A gluon that was red anti-green for example could fragment into a red quark and a green antiquark.

Yes, but we are taking about quark and its own anti-quark like c and c_bar. If c is red, c_bar must be anti-red.

 

[Manojg]

When the q-qbar pair fragments to hadrons, there will be a color connection to the other colored objects in the hadron that contained the original gluon.

Fine, but at every vetex, color (and other like charge) should be conserved, isn't it? So, at vertex where gluon fragments to c and c_bar, color should be conserved.

 

[kaksmet]

Yes, but we are taking about quark and its own anti-quark like c and c_bar. If c is red, c_bar must be anti-red.

No, if the gluon splits up into a red c, the c_bar cannot be anti-red; as far as I understand.

 

[Vanadium 50]

Yes, but you are starting with a colored state, ignoring the rest of the hadron that gave you the gluon. It's that rest of the hadron that solves your problem. You can't ignore it.

 

[tom.stoer]

There is a nice way to represent gluons and color charge conservation in QCD processes.

In a Feynman diagram replace every gluon with a double line, i.e. two antiparallel lines running into opposite direction and carrying a color charge and an anti-color charge, respectively.

http://www.hindawi.com/journals/ahep/2010/floats/723105/thumbnails/723105.fig.002_th.jpg