Main Question or Discussion Point
why photon has no charge though it is produced by either proton and electron, which are both charged??
No, Bosons can have charge, e.g. W+/-.As far as I understand particle physics, a photon is a bosun. As such, it transfers a charge from one place to another, but doesn't have one of its own.
No, I didn't say that, at least I didn't mean to. A photon is always neutral, it couples to electric charge i.e. it can only interact with charged particles but it itself is never charged. NeverOkay, I knew that a photon can be emitted by an electron reverting to ground state, but I didn't realize that it could take the negative charge with it when it left.