# What happens to an electron when it radiates a photon?

I recently came across this Feynman diagram:

For a more simplistic diagram, I suppose even this would be adequate:

As you can see in these diagrams, they radiate these virtual photons. The virtual photons have no charge or mass, and there is no apparent visible change in the energy of the electron after it radiates this photon. I'm aware that the probability level of the incident occurring drops by 1% for every extra vertex in the diagram, so low as the probability can get, it can never touch 0. What stops the electron from radiating multiple photons that can turn into other particles? What change occurs in the electron itself after the emission of the photon?

In the case of quarks and gluons, as seen in the diagram below, the quarks are losing the color charge of the gluon. Therefore, some change must occur in the electron after it radiates the photon.

• "The virtual photons have no charge or mass" - so-called virtual photons are off mass shell, i.e., virtual photons are not massless: As a consequence, a real photon is massless and thus has only two polarization states, whereas a virtual one, being effectively massive, has three polarization states. Commented Dec 30, 2020 at 4:31
• there is clearly no visible change in the energy of the electron after it radiates this photon How is that clear from the diagram? Commented Dec 30, 2020 at 4:39
• the quarks are losing the color charge of the gluon. Therefore, some change must occur in the electron after it radiates the photon The electric charge of an electron does not change when it radiates a photon. Commented Dec 30, 2020 at 4:41
• @AlfredCentauri That's interesting, Thanks for the information! Commented Dec 30, 2020 at 4:47
• My question was to do with what change occurs. The electron’s energy, momentum, and, if I remember correctly, spin state can change. Commented Dec 30, 2020 at 4:49