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We learnt about, among the other three fundamental interactions, the strong interaction. The particles that are affected by it are those with color-charge. It's carrying particles, gluons, have a nonzero color-charge, thus thake part in the interaction themselves. The lecturer made a remark on that's makes the interaction so complicated, and intuititively it indeed does - but how exactly? We proceeded describing the color-symmetry (color-octet/singlet, Gell-Mann matrices, etc.) and looked at an example interaction (showing how the color-charge changes), but we never actually explained how the charged property of the carrying particle changes things. The three different charge makes it hard to come up with an intuitive picture - so I'd like to consider an analogue.

Take the electromagnetic force. It's working is well-known and intuitive, with a single kind of charge. It's carrying particle, photon, is as massless as the gluons, but it has a zero electromagnetic charge - so they don't participate in the interaction, only transmit it. Change now one property of the photon: make it have a nonzero q charge.

How would this interaction, with one charge and a weightless charged carrying particle be different from the electromagnetic force, both subatomically (-> Feynmann-diagram) and macroscopically? (Or is there some theorem that forbids even the theoretic existence of such a force?)

As an example: would we experience something alike the color confinement? Would it still have infinite range? Would particles change charge during interactions? etc. What I'm looking for is an intuitive picture about what does the color-charge of the gluons cause.

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  • $\begingroup$ I want you to get an answer from people much better at this than I, but your title question If photons had charge, how would the electromagnetic interaction be different has two problems, imo.1. Its very general (i.e. what type of charge, how much charge...) 2. but more importantly, you want an answer to the result of breaking a law of nature, but in terms of other laws of nature. Once you start down that road, you are in effect, asking for opinions on alternate universes. $\endgroup$ – user181180 Jan 16 '18 at 18:16
  • $\begingroup$ but it has a zero electromagnetic charge - so they don't participate in the interaction, only transmit it. The photon does get involved, it transfers momentum. What I'm looking for is an intuitive picture about what does the color-charge of the gluons cause. I don't think group theory allows for useful mental pictures. $\endgroup$ – user181180 Jan 16 '18 at 18:23
  • $\begingroup$ @Countto10 I disagree. True, I don't know how well the propertities of the fundamental forces are theoretically estabilished, but - as we lack a real fundamental theorem - I think they're closer to being axioms based on experimental results, than being actual laws. As such, I'm not sure - but I asked it - if there's anything that rules out the theoretical possibility of an interaction analogous to an electromagnetic interaction with a charged carrying particle. $\endgroup$ – Neinstein Jan 16 '18 at 18:26
  • $\begingroup$ @Countto10 Regarding the group theory, I must admit I have zero knowledge on that topic. An answer describing how the group theory forbids such a force is thus - intentionally - a valid answer... $\endgroup$ – Neinstein Jan 16 '18 at 18:31
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    $\begingroup$ The color charges lead to confinement, as gluons also are attracted to each other. Photons do not interact . Confined electromagnetism would give a different universe, if it would work. $\endgroup$ – anna v Jan 16 '18 at 18:31

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