Two-loop corrections to the orthopositronium and parapositronium decay rates due to vacuum polarization

We have calculated all O(${\mathrm{\alpha }}^2$) corrections to the orthopositronium and parapositronium decay rates due to vacuum polarization graphs. These contributions are independent of gauge and bound state formalism. Our results are +0.964 960(4) (α/π${)}^2$ for orthopositronium and +0.447 343 0(6) (α/π${)}^2$ for parapositronium relative to the lowest order rates. We also have an improved result for the one-loop one-photon-annihilation orthopositronium decay graph of -0.814 057 4(10) (α/π) times the lowest order rate.