Zero or one vertex

1
Field-Stuart-HaasPRD
Charged Particle Data
QCD Monte-Carlo
WYSIWYG What you see is what you get. Almost!
Select clean region
Make efficiency corrections
Look only at the charged particles measured by
the CTC.

• Zero or one vertex
• zc-zv lt 2 cm, CTC d0 lt 1 cm
• Require PT gt 0.5 GeV, h lt 1
• Assume a uniform track finding efficiency of 92
• Errors include both statistical and correlated
  systematic uncertainties

• Require PT gt 0.5 GeV, h lt 1
• Make an 8 correction for the track finding
  efficiency
• Errors (statistical plus systematic) of around 5

compare
Small Corrections!
Corrected theory
Uncorrected data
2
Charged Particle DfCorrelations

• Look at charged particle correlations in the
  azimuthal angle Df relative to the leading
  charged particle jet.
• Define Df lt 60o as Toward, 60o lt Df lt 120o
  as Transverse, and Df gt 120o as Away.
• All three regions have the same size in h-f
  space, DhxDf 2x120o 4p/3.

3
Charged Multiplicity versus PT(chgjet1)
Underlying Event plateau
Blessed on 11/3/99

• Data on the average number of toward
  (Dflt60o), transverse (60ltDflt120o), and
  away (Dfgt120o) charged particles (PT gt 0.5
  GeV, h lt 1, including jet1) as a function of
  the transverse momentum of the leading charged
  particle jet. Each point corresponds to the
  ltNchggt in a 1 GeV bin. The solid (open) points
  are the Min-Bias (JET20) data. The errors on the
  (uncorrected) data include both statistical and
  correlated systematic uncertainties.

4
Transverse Nchg versus PT(chgjet1)
Isajet 7.32
Pythia 6.115
Herwig 5.9
Blessed on 11/3/99

• Plot shows the Transverse ltNchggt versus
  PT(chgjet1) compared to the the QCD hard
  scattering predictions of Herwig 5.9, Isajet
  7.32, and Pythia 6.115 (default parameters with
  PT(hard)gt3 GeV/c).
• Only charged particles with h lt 1 and PT gt 0.5
  GeV are included and the QCD Monte-Carlo
  predictions have been corrected for efficiency.

5
Transverse PT Distribution

• Plot shows the PT distribution of the
  Transverse ltNchggt. Each point corresponds to
  the dltNchggt/dPT in a 1 GeV bin.
• The triangle and circle (square) points are the
  Min-Bias (JET20) data. The errors on the
  (uncorrected) data include both statistical and
  correlated systematic uncertainties.

Needs Blessing
6
Transverse PT Distribution

• Plot shows the data on the PT distribution of the
  Transverse ltNchggt for PT(chgjet1) gt 2 GeV/c
  compared with the QCD hard scattering prediction
  of HERWIG.
• The dashed (solid) curves show the contribution
  arising from the beam-beam remnants (total).

Needs Blessing
7
Transverse PT Distribution

• Plot shows the data on the PT distribution of the
  Transverse ltNchggt for PT(chgjet1) gt 30 GeV/c
  compared with the QCD hard scattering prediction
  of HERWIG.
• The dashed (solid) curves show the contribution
  arising from the beam-beam remnants (total).

Needs Blessing
8
Transverse PT Distribution

• Plot shows the data on the PT distribution of the
  Transverse ltNchggt for PT(chgjet1) gt 30 GeV/c
  compared with the QCD hard scattering prediction
  of HERWIG, ISAJET, and PYTHIA 6.115.

Needs Blessing