Studies of two particle correlation functions and photon-tagged jet fragmentation in PbPb and pp Collisions with CMS at the LHC

Abstract

This thesis studies of two particle correlations in proton-proton (pp), proton-lead (pPb), and lead-lead (PbPb) collisions, as well as jet fragmentation functions for jets paired with an isolated prompt photon in pp and PbPb collisions to better understand matter in a Quark Gluon Plasma (QGP) state. The correlation studies measure the precise hydrodynamic behavior of PbPb collisions through a Fourier analysis of charged particles emitted from the QGP and show unexpectedly strong collective behavior in high multiplicity pp and pPb collisions. The photon-tagged jet studies provide tight constraints for understanding the interactions between the jet and the Quark Gluon Plasma it traverses by both measuring the jet substructure properties via the fragmentation function, and having a sample of jets unbiased by the interactions we are trying to probe by selecting high energy photon events. These analyses are performed using data recorded by the CMS experiment at the LHC from PbPb, pPb, and pp collisions at a center of mass energy of 5.02 TeV per nucleon-nucleon pair, as well as 2.76 TeV PbPb collisions and 7 TeV pp collisions in the correlation analyses.