Leading Cluster of Jets in pp collisions


Several models were delevoped to study high energy physics. Final states of high energy collisions are well predicted by different event generators, but discrepancies have been found in various corners of the phase space. Further investigations are needed to test the prediction of event generators and different models. Comparative study of quark and gluon jets also helps to understand the hadronization processes.

Leading cluster of jets

Intrinsic structure of the jets are well described by the hadronization processes. Leading particles at large momentum fraction contain the partons of the initial interaction. Leading cluster can be separated measuring the pseudorapidity of the particles with respect to the jet axis. Sorting the particles regarding to the new y values helps to locate the leading part inside the jet. If there is
an interval in rapidity which is not occupied by any of the particles, the leading cluster is the group that has higher eta.

e+e- Monte Carlo events

Analysis has been performed at LEP. Hadronic decays of the Z0 boson after the e+ e- collision can produce two quark jets and one gluon jet can appear from gluon radiation. These three-jet events have been used to study the process of color reconnection (CR). High radidity gap inside jets is also required. Rapidity gap in gluon jets can be related to color reconnection. Three-jet events are selected to perform the leading cluster analysis. Jets with the highest pT in three-jet events marked as quark jets and the lowest ones are counted as gluon jets. κ_{jet} cut has been applied to select events with well separated gluon and quark jets. Properties of the event generation are shown below.

Nr of events 1 million
√s mZ
Process e+e- -> Z0 -> b bbar + g
Jet finder Durham
# of jets 3
# of charged tracks > 4
κ > 7GeV
Egluonjet < 35GeV

κ distribution of gluon jets

κ distribution of gluon jets

Minimum rapidity values (ymin) inside gluon jets with respect to the jet axis

Maximum rapidity gap inside gluon jets

Leading cluster population of gluon jets without rapidity gap cut (left) and Δymax > 1.3 (right).

Leading cluster charge distribution of gluon jets without rapidity gap cut (left) and Δymax > 1.3 (right).

-- AttilaJozsefRadl - 2018-10-22

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf cluster_ee_gluon_charge.pdf r2 r1 manage 13.4 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PDFpdf cluster_ee_gluon_charge_rapgap.pdf r2 r1 manage 13.3 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PDFpdf cluster_ee_gluon_leadingpop.pdf r2 r1 manage 13.5 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PDFpdf cluster_ee_gluon_leadingpop_rapgap.pdf r2 r1 manage 13.5 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PDFpdf cluster_ee_gluon_rapgap.pdf r2 r1 manage 13.6 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PDFpdf cluster_ee_gluon_ymin.pdf r2 r1 manage 13.6 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PDFpdf clusterjet_ee_kappa.pdf r2 r1 manage 13.9 K 2018-10-24 - 00:29 AttilaJozsefRadl  
PNGpng clusterjet_ee_kappa.png r1 manage 81.6 K 2018-10-24 - 10:18 AttilaJozsefRadl  
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Topic revision: r5 - 2018-10-24 - AttilaJozsefRadl
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