Kinematic variables

$\displaystyle Q^2$	$\textstyle =$	$\displaystyle 2EE^\prime(1-\cos\theta)$	(17)
$\displaystyle y$	$\textstyle =$	$\displaystyle \frac{\nu}{E}$	(18)
$\displaystyle R$	$\textstyle =$	$\displaystyle {\sigma_L}/{\sigma_T}=\frac{1+\gamma^2}{2x}\frac{F_2}{F_1}-1$	(19)
$\displaystyle D^\prime$	$\textstyle =$	$\displaystyle \frac{(1-\epsilon)(2-y)}{y(1+\epsilon R(x,Q^2))}$
$\displaystyle \gamma^2$	$\textstyle =$	$\displaystyle \frac{Q^2}{\nu^2}=\frac{(2Mx)^2}{Q^2}$	(20)
$\displaystyle \epsilon$	$\textstyle =$	$\displaystyle 1/[1+2(1+1/\gamma^2)\tan^2(\theta/2)$	(21)
$\displaystyle D$	$\textstyle =$	$\displaystyle \frac{1-\epsilon E'/E}{1+\epsilon R}$	(22)
$\displaystyle \eta$	$\textstyle =$	$\displaystyle (\epsilon\sqrt{Q^2})/(E-E'\epsilon)$	(23)
$\displaystyle \xi$	$\textstyle =$	$\displaystyle \eta(1+\epsilon)/(2\epsilon)$	(24)
$\displaystyle d$	$\textstyle =$	$\displaystyle D\sqrt{2\epsilon/(1+\epsilon)}$	(25)