Multiplicity in pp and AA collisions: the same power law from energy-momentum constraints in string production

We show that the dependence of the charged particle multiplicity on the centre-of-mass energy of the collision is, in the String Percolation Model, driven by the same power law behavior in both proton-proton and nucleus-nucleus collisions. The observed different growths are a result of energy-momentum constraints that limit the number of formed strings at low energy. Based on the very good description of the existing data, we provide predictions for future high energy LHC runs.