1. Nuclear Physics Seminar

    "Recent Experimental Results on QCD Factorization Breaking of Nonperturbative Functions"

    Presented by Joe Osborn

    Tuesday, October 25, 2016, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Jin Huang

    In the last two decades the study of nucleon structure has shifted from a one-dimensional picture to exploring the dynamic three-dimensional structure of partons within the nucleon. In the transverse-momentum-dependent framework, nonperturbative parton distribution functions (PDFs) and fragmentation functions (FFs) explicitly carry dependence on partonic transverse momentum rather than only the collinear momentum of the parton with respect to the hadron or produced hadron with respect to the fragmenting parton. The recent interest in the transverse structure of the nucleon has largely been motivated by the novel phenomenological consequences that have been predicted for transverse-momentum-dependent nonperturbative functions. Contrary to the collinear framework, certain transverse-momentum-dependent PDFs are predicted to be process dependent. Additionally, factorization breaking has been predicted in hadronic collisions where a final-state hadron is measured and the observable is sensitive to nonperturbative transverse momentum. This prediction has the interesting quantum mechanical consequence that partons are correlated with each other across the bound state hadrons, rather than being identified with individual PDFs and FFs. Recent results from the PHENIX experiment at the Relativistic Heavy Ion Collider will be shown which investigate effects that are predicted to be sensitive to the nonperturbative factorization breaking.