Title: Transverse Geometry of the Hard and Soft pp and pA Collisions at the LHC
Speaker: Mark Strikman (PSU)

Abstract: Decades of studies of hard QCD phenomena provided a precision picture of the distribution of proton constituents (quarks and gluons) over the fraction of energy, x, which they carry in fast nucleons. More recently, studies of the hard exclusive processes provided first information about three dimensional structure of fast nucleons – the x-dependent impact parameter single parton distributions in the nucleon and led to the two scale geometric picture of the proton – proton interactions at the LHC. I will review how this picture explains a number of regularities of hadron production observed at the LHC, and reveals presence of the parton – parton correlations in nucleons. I will also present evidence for existence of significant fluctuations of gluon strength in nucleons as well as fluctuations of the overall strength of the interactions and discuss implications for pp and pA collisions.