Gluons in quantum chromodynamics (QCD) come in eight color charge varieties. But, it has never been clear to me if they differ from each other in other respects the way that, for example, photons do. Obviously, they also have a direction and location associated with them (subject to the uncertainty principle) and presumably, as massless bosons, always travel as the speed of light.

Do they have different frequencies or differing amounts of energy? Do they have different helicity? Do they have polarizations or chirality that is distinct from color charge? Are there other possible properties that I've overlooked?


1 Answer 1


Gluons are essentially a more complicated version of photons; their colours are just a multidimensional analogue of electric charge (which photons don't even have, because electromagnetism isn't self-interacting). In particular, gluons are massless spin-$1$ bosons. This gives the same polarisation, chirality and helicity details as photons, and an arbitrary four-momentum (satisfying $k_\mu k^\mu=0$ if the gluon is real).

  • $\begingroup$ Thanks, that is very helpful, clear and succinct. I am inclined to accept this answer, but will wait a bit to see if anyone else has something useful to add. $\endgroup$
    – ohwilleke
    Commented Jul 10, 2017 at 16:41

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