Effective photon charge in relativistically hot electron-positron plasmas

We present an expression for the effective charge of photons in a relativistic hot electron-positron plasma. For this purpose, we use the electron density perturbation that is driven by the photon ponderomotive force and compare the resultant electron charge density with the photon charge density. It is found that the photon charge depends on the plasma frequency, the plasmas temperature, as well as on the photon frequency. The relevance of our investigation to nonlinear couplings between photons and relativistically hot pair plasmas is mentioned.