Jet properties in low and high multiplicity events in p-p collisions at 7 TeV

Collaboration
2012
34 pages
Report number:
  • CMS-PAS-FSQ-12-022
Experiments:

Citations per year

20122013201401
Abstract:
The characteristics of multi-particle production in p-p collisions at s=7\sqrt{s}=7 TeV are studied as a function of the event charged particle multiplicity (NchN_{\rm ch}), by classifying the measured tracks into two distinct classes, those belonging to jets and those belonging to the underlying event (UE). Charged tracks are measured within pseudorapidity η<|\eta|< 2.4 and transverse momenta above pTp_{T}~=~0.25~GeV/c, and charged-particle jets are reconstructed above pTp_{T}~=~5~GeV/c with track-only information. The distributions of jet pTp_{T}, average pTp_{T} of UE tracks and jets, jet rates, and jet shapes are studied as a function of NchN_{\rm ch} and are compared to the predictions of the \textsc{pythia} and \textsc{herwig} Monte Carlo (MC) event generators. As the event-multiplicity increases, \textsc{pythia} systematically predicts higher jet rates and harder pTp_{T} spectra than seen in the data, whereas \textsc{herwig} shows the opposite trend. Predictions without multi-parton interactions fail completely to describe the data. In the lowest-multiplicity events, the data show narrower jets than predicted by both MC generators.
Note:
  • CMS Physics Analysis Summary - preliminary results
  • Data
  • p p: scattering
  • jet: multiplicity
  • hadron: multiple production
  • charged particle: multiplicity
  • multiplicity: dependence
  • track data analysis: jet
  • shape analysis: jet
  • Monte Carlo
  • HERWIG