What does the matter created in high multiplicity proton-nucleus collisions teach us about the 3-D structure of the proton?

Understand

The study of multiparticle correlations and collectivity in the hot and dense matter created in collisions of heavy-ions as well as those of smaller systems such as proton--heavy-ion collisions has progressed to the point where detailed knowledge of the three-dimensional structure of the proton is needed to confront experimental data.

• We discuss results from a simple proof-of-principle initial state parton model which reproduces many features of the data on proton--heavy-ion collisions that are often ascribed to hydrodynamic flow.
• We outline how this model can be further improved with particular emphasis on missing elements in our understanding of the dynamical spatial and momentum structure of the proton.