Forest VirtualRealPhoton

Polarized Virtual Photons From Electrons

Virtual Photon Polarization

$\epsilon= \left [ 1 + 2 \left ( 1 + \frac{\nu^2}{Q^2}\right ) \tan^2\left( \frac{\theta_e^{\prime}}{2}\right)\right ]$

Longitudinal Photon Polarization

$\epsilon_L= \frac{Q^2}{\nu^2}\epsilon$

Polarization Density Matrix

$\begin{bmatrix} \frac{1}{2}(1+\epsilon) & 0 & -1 \sqrt{\frac{1}{2}\epsilon_L(1+\epsilon)}\\ 0 & \frac{1}{2}(1-\epsilon) & 0\\ -1 \sqrt{\frac{1}{2}\epsilon_L(1+\epsilon)} & 0 & \epsilon_L\\ \end{bmatrix}$

Reference: N. Dombey, Rev. Mod. Phys., 41, 236 (1969)

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