Status Report of electron response in f crack

1
Status Report of electron response in f crack

• Universiry of Rochester
• Yeonsei Chung, Geumbong Yu

2
For study

• 1 million MC(Z?ee) used
• ?Zewkae Pythia MC with min bias events
• Data set of bhel0d (high pt electron)
  454 files read(48G)
• Eta towers, 1932, used for both of electron and
  track.
• For electron, tight central electron cut used
  except Et cut.
• Cut strategy is to have clean Z sample by every
  possile tight cut.

3
Track selection

• Track pt gt 20 GeV
• Opposite charge to electrons
• E/plt2.0
• Had/Emlt0.05
• No other track within 0.4 cone of track.
• All energy used in cut is 2x2 Cal energy.
• To make similar condition of track with electron,
  raise track pt cut to 20 GeV.

Footnote we found the electron Etgt25 GeV cut
make bias in comparing E/p distribution of track
and electron(higher E/p of electron than track).
Therefore we tried to apply ptgt20GeV to both of
el and track.
4
Z mass
To reconstruct Z we used 2x2 Cal data and track
momentum for 4-vector of track. Emobject used for
electron 4-vector.
Monte Carlo Data
2x2 Cal E
Track Mom
5
Zmass
Selected Zmass 80lt MZ lt 100
2x2 Cal E
Track Mom. used
Black overall dist. Blue rphilt0.9 Green
rphigt0.9 Data in dot
trk rphilt0.9
In the case of Cal data, Z mass are strongly
affected by hit position of phi since we lost
energy in crack. But if we use track momentum
for 4-vector of track, the shape is not changed
by Relative phi position.
trk rphigt0.9 Crack region
6
Zmass
Black overall dist. Blue rphilt0.9 Green
rphigt0.9 Data in dot
Compare events in rphigt0.9 of track with
rphilt0.9. Obviously theres mismatch in Zmass
with Cal E.
7
Selected Zmass with Cal Eafter 80ltM(Z,trk)lt100
cut
Monte Carlo Data
In addition to the M(Ztrk) mass cut, we require
rphilt0.8 of electron to reduce possible
background on electron leg.
overall dist.
Trk rphilt0.9
Trk rphigt0.9
8
E/p
We have seen the E/p dist. of crack region
(either electron of track) is different from
non-crack area.
Black overall dist. Blue rphilt0.9 Green
rphigt0.9 Data in dot
Single Tower Cal energy Track Momentum
Electron
Track
9
E/p
Electron
Track
Black overall dist. Blue rphilt0.9 Green
rphigt0.9
Data in dot
Does the high E/p distribution mean background
on electron leg?
10
Zmass in el crack
Combined
Blue rphilt0.9 Green rphigt0.9 Data in dot
11
Had/Em(track)
2x2 Had Cal Energy 2x2 EM Cal Energy
Black overall dist. Blue rphilt0.9 Green
rphigt0.9 Data in dot
Tight central electron cut including sliding
Had/Em cut already was applied to electron
leg. To have track cut, we plotted normalized
Had/Em dist. Had/Em on track less than 0.05
selected to have clean Z sample.
12
Had/Em
Data shows sharper Had/Em in low but more
fluctuation in high region.
Black overall dist. Blue rphilt0.9 Green
rphigt0.9 Data in dot
13
Events in rel. position
Rel. phi
Rel. eta
Monte Carlo Data
Electron
We have flat relative phi distribution of track
without requiring em object
Track
14
E/p vs rel. phi rel. eta
Rel. phi
Rel. eta
Monte Carlo Data
Electron
Track
15
E/p vs rel. phi rel. eta
Rel. phi
Rel. eta
Monte Carlo Data
Electron
Just blowup of Previous page
Have correction on Cal Data?
Track
16
E/p vs. rel. phi rel. eta
Emobject E/p variable shows flat distribution
after correction but we dont have no way to see
how track response change.
Rel. phi
Rel. eta
17
Cal energy distribution in phi
Monte Carlo Data
Electron
Track
18
Cal energy distribution in eta
Monte Carlo Data
Electron
Track
19
Summary

• To study crack response properly, we had to use
  track momentum instead of Cal energy for clean Z
  sample.
• We used ptgt20 cut for both of electron and track
  to make a fair comparision of E/p profile.
• Theres a discrepancy between MC and data in phi,
  electron and track in eta. It needs to be
  understood.