σ_{T} = \frac{8π}{3} (\frac{e^{2}}{m_{e}c^{2}} )^{2} = 6.65 × 10^{−25} cm^{2}

κ_{λ} = κ_{λ,bb} + κ_{λ,bf} + κ_{λ,ff} + κ_{es}

\overline{κ} = \overline{κ_{bb} + κ_{bf} + κ_{ff} + κ_{es}}