The color glass condensate and hadron production in the forward region

We consider one loop corrections to single inclusive particle production in parton–nucleus scattering at high energies, treating the target nucleus as a color glass condensate. We prove by explicit computation that in the leading logQ2 approximation, these corrections lead to collinear factorization and DGLAP evolution of the projectile parton distribution and hadron fragmentation functions. In single-inclusive cross sections, only two-point functions of Wilson lines in the adjoint and fundamental representations (Mueller's dipoles) arise, which can be obtained from the solution of the JIMWLK equations. The application of our results to forward-rapidity production shows that, in general, recoil effects are large. Hence, the forward rapidity region at RHIC is rather different from the central region at LHC, despite comparable gluon densities in the target. We show that both the quantum x-evolution of the high-density target as well as the DGLAP Q2-evolution of the parton distribution and fragmentation functions are clearly seen in the BRAHMS data. This provides additional strong evidence for the color glass condensate at RHIC.