Heavy ion collision multiplicities and gluon distribution functions

Atomic number ($A$) and energy ($\roots$) scaling exponents of multiplicity and transverse energy in heavy ion collisions are analytically derived in the perturbative QCD + saturation model. The exponents depend on the small-$x$ behaviour of gluon distribution functions at an $x$-dependent scale. The relation between initial state and final state saturation is also discussed.

K.J. Eskola, K. Kajantie, K. Tuominen · 2001