Implications of space-momentum correlations and geometric fluctuations in heavy-ion collisions

The standard picture of heavy-ion collisions includes a collective expansion. If the initial energy density in the collisions is lumpy, then the expansion can convert the spatial lumpiness into correlations between final-state particles. Correlations in heavy-ion collisions show prominent features not present in p+p collisions. I argue that many features of these correlations are related to the transference of over-densities from the initial overlap region into momentum-space during the QGP phase of the expansion. I show results from a toy Monte Carlo model to illustrate the consequences of lumpy initial conditions and a collective expansion.