Theory

Quark distribution Functions

Polarized

The inclusive double polarization asymmetries $A_N$ can be written in terms of polarized $\triangle q_v (x)$ and unpolarized $q_v (x)$ valence quark distributions,

$\frac {4\triangle u_v (x) + \triangle d_v (x)} {4 u_v (x) + d_v (x)}$
$\frac {\triangle u_v (x) + 4\triangle d_v (x)} {u_v (x) + 4d_v (x)}$