CES

1
CES CPR PHOTON BACKGROUND ESTIMATION
T. Davies

• Investigation into CES and CPR photon
  background estimation with a view of combining
  the two into a single measurement
• CES and CPR weights are calculated for ISO 25
  and ISO 10 data and compared with those
  calculated with Pythia and Herwig Monte Carlo
  simulations

2
Photon Selection Cuts
The photon cuts differ slightly from the
recommended cuts www-cdf.fnal.gov/internal/physic
s/photon/docs/cuts.html

• Hadronic/Em lt0.055 0.00045 EtCorr
• c2 mean (over strips and wires) lt 20
• N3D 0 (for the CPR method)
• Cone 0.4 IsoEtCorr lt 2.0 0.02EtCorr
• (the case for EtCorrgt20 has IsoEtCorr lt
  1.6 0.02EtCorr)
• Cone 0.4 Track Iso lt 2.00.005EtCorr
• 2nd CES cluster for both Strips and Wires lt 1GeV
  (for CES Method)
• Ces X lt 17.5cm (for CES method)
• 9cm lt Ces Z lt 230cm

A Good Run list is also used
3
Data Sample
The Data is taken from ISO 25 dataset (cph10d) at
200pb-1 and from the ISO 10 data found in the
diphoton dataset (cdip0da) at 400pb-1
number of events
Photon Et (GeV)
4
Photon Content Estimated by CES (green) and CPR
(blue)
number of events
Photon Et (GeV)
5
CES (green) and CPR (blue) Photon Weights from
both Data sets
Weight
Photon Et (GeV)
6
Weight Cross Check Between the Two Data Sources
(triggers ISO 25 and 10)

• ISO 25 (Black) an ISO 10 (coloured) sets roughly
  agree in areas of mutually high statistics

CPR comparison of ISO 25 (Black) and ISO 10
(Blue) data
CES comparison of ISO 25 (Black) and ISO 10
(Green) data
Weight
Photon Et (GeV)
Photon Et (GeV)
7
Weights Calculated with an Explicit Function Call
As a Check, the CES (Green) and CPR (Blue)
weights were recalculated with an explicit call
to the photon background computer function. The
plots below show the difference between the
StNtuple weights and those calculated explicitly
Difference in Weight
Difference in Weight
Photon Et (GeV)
Photon Et (GeV)
8
Monte Carlo Sample

• The Monte Carlo sample were 5.3.3 Pythia and
  Herwig photon samples
• For each generator, samples with pt mins of 8, 12
  and 22 GeV were included

number of events
Photon Et (GeV)
9
Monte Carlo Photon Content

• Estimated by CES (green) and CPR (blue)
• Due to little background, the CES Method over-
  estimates the photon content, and the CPR
  method indicates no background

number of events
Photon Et (GeV)
10
Monte Carlo CES and CPR Weights

• CES method over-estimates at all times, but get
  larger for higher photon Et
• CPR weight is roughly 1 over all Et

Weight
Photon Et (GeV)
11
Pythia and Herwig Comparisons

• The weights in the Pythia (always shown in black)
  and Herwig sets over all pt min ranges agree for
  both CES and CPR

CPR comparison from Pythia (Black) and Herwig
(Blue)
CES comparison from Pythia (Black) and Herwig
(Green)
Weight
Photon Et (GeV)
Photon Et (GeV)
12
Monte Carlo pT min Comparisons

• CPR Weights for different pT min generations are
  all consistently level at 1
• The upward trend in CES weight is only seen in
  the pT min 22 sample

CES comparison of pTmin 12 (Black) and pTmin 22
(Green)
CES comparison of pTmin 8 (Black) and pTmin 22
(Green)
Weight
Photon Et (GeV)
Photon Et (GeV)
13
Data and Monte Carlo comparisons of CES Weight

• Data (Black) and Monte Carlo (Green) CES weights

Weight
Photon Et (GeV)
14
Data and Monte Carlo comparisons of CPR Weight

• Data (Black) and Monte Carlo (Blue) CPR weights

Weight
Photon Et (GeV)