Next-to-eikonal corrections in the CGC: gluon production and spin   asymmetries in pA collisions
  We present a new method to systematically include corrections to the eikonal approximation in the background field formalism. Specifically, we calculate the subleading, power-suppressed corrections due to the finite width of the target or the finite energy of the projectile. Such power-suppressed corrections involve Wilson lines decorated by gradients of the background field - thus related to the density - of the target. The method is of generic applicability. As a first example, we study single inclusive gluon production in pA collisions, and various related spin asymmetries, beyond the eikonal accuracy. 
Tolga Altinoluk, N\'estor Armesto, Guillaume Beuf, Mauricio Mart\'inez   and Carlos A. Salgado
hep-ph