Effective photon mass from black-hole formation

We compute the value of effective photon mass mγ at one-loop level in QED in the background of small (1010 g≲M≪1016 g) spherically symmetric black hole in asymptotically flat spacetime. This effect is associated with the modification of electron/positron propagator in presence of event horizon. Physical manifestations of black-hole environment are compared with those of hot neutral plasma. We estimate the distance to the nearest black hole from the upper bound on mγ obtained in the Coulomb-law test. We also find that corrections to electron mass me and fine structure constant α at one-loop level in QED are negligible in the weak gravity regime.