We propose a new formalism that aims to unify particle production in high energy hadron/nucleus collisions; from collinear factorization approach in pQCD at high $p_t$ (large $x$) to Color Glass Condensate framework which describes multi-particle production at low $p_t$ (small $x$). To do so we consider scattering of a quark projectile from a classical color field representing small $x$ gluons of the target to all order in the field and a dynamical gluon field representing large $x$ gluons of the target proton or nucleus. We then compute the "tree-level" scattering cross section. We discuss the effects of the one-loop corrections to our tree-level cross section which is expected to lead to leading twist pQCD and DGLAP evolution equation of the cross section at high $p_t$ and the JIMWLK evolution equation of Color Glass Condensate at low $x$.