Bulk hadron production at high rapidities

Abstract

Recent experimental observations on the `bulk' features of particle production at high (pseudo)rapidities will be reviewed. This kinematic region is of interest mostly because of its relevance to the theoretical description of initial state effects of nuclei at ultra-relativistic energies. Measurements of the charged hadron multiplicity density as well as the pseudorapidity dependence of the elliptic and directed flow exhibit a remarkable scaling property as a function of collision energy. This scaling seems to hold for pions and even photons and J/Psi-s, but is violated for protons. The special role of baryons will be discussed using selected results on nuclear transparency and baryon stopping.Comment: 10 pages, 8 figures. Prepared for the Proceedings of the Quark Matter 2005 Conferenc