1. Nuclear Physics Seminar

    "New insights on the "Ridge" in pp and pA at the LHC"

    Presented by Wei Li, Rice University

    Tuesday, May 14, 2013, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Anne Sickles

    The observation of a long-range, near-side two-particle angular correlation in very high multiplicity proton-proton (pp) and proton-lead (pA) collisions at the LHC has changed our view of multiparticle production in these small systems. This phenomenon, known as the "Ridge", was first seen in high energy nucleus-nucleus (AA) collisions at RHIC, and is believed to be related to the collective evolution of a strongly interacting QCD matter created in AA. In this talk, I will first briefly review the history of ridge studies in AA and unexpected discovery of the ridge correlations in pp and pA systems. Focus will then be given to the most recent results of pA collisions at CMS from 2013 LHC run on two- and multi-particle correlations. I will discuss the new insights these results provide us toward disentangling different theoretical interpretations (i.e. CGC v.s. flow) to the physical origin of the ridge phenomenon in small systems of pp and pA.