Testing Photons\u27 Bose-Einstein Statistics With Compton Scattering

It is an empirical question whether photons always obey Bose-Einstein statistics, but devising and interpreting experimental tests of photon statistics can be a challenge. The nonrelativistic cross section for Compton scattering illustrates how a small admixture ν of wrong-sign statistics leads to a loss of gauge invariance; there is a large anomalous amplitude for scattering timelike photons. Nevertheless, one can interpret the observed transparency of the solar wind plasma at low frequencies as a bound ν\u3c10−25 if Lorentz symmetry is required. If there is instead a universal preferred frame, the bound is ν\u3c10−14, still strong compared with previous results