Study of jet quenching using di-jet and photon-jet events in PbPb collisions at 2.76 TeV with CMS

Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus–Nucleus Collisions 2012

Kim, Yongsun^1

24-519 Heavy Ion Group, 77 Massachusetts Avenue, Cambridge, MA, United States^1

关键词: Center-of-mass energies;    Fragmentation functions;    Integrated luminosity;    Jet fragmentation;    Parton energy loss;    Pb-Pb collisions;    Relativistic heavy ion collision;    Transverse momenta;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/446/1/012007/pdf
DOI  :  10.1088/1742-6596/446/1/012007

来源: IOP

【 摘 要 】

The first measurement of the transverse momentum imbalance of isolated-photon-jet pairs and the modification of fragmentation function of the inclusive jets in relativistic heavy ion collisions are reported. The analysis uses data from PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair and corresponding to an integrated luminosity of 150 μb-1recorded by the CMS experiment at the LHC in 2011. For events containing an isolated photon with transverse momentum pT> 60 GeV/c and an associated jet with pT> 30 GeV/c, the photon-jet pTimbalance is studied as a function of collision centrality and compared to pp data and PYTHIA calculations at the same center-of-mass energy. Using the pTof the isolated photon as an estimate of the energy of the associated parton at production, this measurement allows an unbiased characterization of the in-medium parton energy loss. In addition, further study on the modification of jet fragmentation function was studied using inclusive jets with pT> 100 GeV/c. Both show the gradual centrality dependence of jet energy loss and fragmentation function modification.