ALICE measures pA collisions: Collectivity in small systems?

Proton-nucleus collisions provide a reference for heavy ion-collisions, to study the signatures deriving from the presence of a complex nuclear structure in the initial state, which confirm that the suppression of high-p (T)hadron production observed in heavy-ion collisions is a genuine effect of the hot deconfined QGP. However, several measurements of particle production in the low and intermediate momentum region indicate the presence of coherent and collective effects, already in small systems, such as the ones produced in p-Pb collisions. Measurements from proton-lead collisions at √s(NN) = 5.02 TeV obtained by the ALICE experiment at the CERN LHC will be presented and compared to p-p, A-A and d-A experimental results at different collision energies and to the available theoretical model predictions.