v 7.6

ε = 1 + \frac{N e^{2}}{ε_{0} m_{e}} \frac{1}{[(ω_{0}^{2} - ω^{2}) + i ω γ]}

${\varepsilon =1+ \frac{Ne^2}{\varepsilon_0 m_e } \frac{1}{[(\omega_0^2-\omega^2 )+ i\omega \gamma]}}$