Three-Point Spectral Density in QED and the Ward Identity at Finite Temperature

We derive the spectral representations of QED 3-point functions and then explicitly calculate the 3-point spectral densities in hard thermal loop approximation within the real time formalism. The Ward identities obeyed by the retarded and advanced 2- and 3-point functions are discussed. We compare our results with those for hot QCD .Comment: 16 pages, 1 figure, some corrections in sec1, sec.