<math>p_\mathrm{total} = 8 \chi^3 \frac{T}{T_0} + F(\chi) + \frac{8\pi^4}{15} \biggl( \frac{T}{T_0} \biggr)^4</math>
where, <math>T_0 \equiv \frac{m_e c^2}{k}</math> .
