two photon process veto efficiency 4-aug-2006 a.miyamoto preliminary status report
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Two photon processveto efficiency
4-Aug-2006A.Miyamoto
Preliminary status report
Two photon background data Generator data
Generated by Kurihara san using GRACE Full 4 fermion diagram: e+e- e+e-+-, No ISR, NoBS Conditions of event generation
Ecm = 500 GeV prod of each final particles > 5mrad E of each final particles : 1~500 GeV
Total Cross section 9.04 pb
Distributions at generator level and result by quick simulator are studied, using 100k events, corresponding to ~11/fb
e- distribution at L=4.5mA hall by 5mrad cut
at generation
X(cm)
Y(cm
)
Exit hall of r=2cm,With 14mrad crossing
Max(rd1,rd2) distribution If both e-,e+ are requested to go through exit beam hall of radius
2cm, 47 events remains for 11/fb data
Max(rd1,rd2)
Integral of blackhistogram
47 events ifMax(rd1,rd2)=2cm
Missing PT ofmax(rd1,rd2)<2.0cmevents
From generator data(after tau decay)
From Quick Simulator data~20events above Pt Miss > 2.5 GeV
2.5 GeV
Max(rd1,rd2)<2.0cmEvis>2.0 GeV
rd1 and rd2 aredetermined by generator data
Azimuthal angle Of missing Pt vector
From Generator data
Quick Simulator
Pt>5.0 events
Pt>2.0 Events
Azimuthal angle(Radian)
Azimuthal angle(Radian)
Quick Simulator: Missing Pt vs Azimuthal angle of missing Pt vector
2.5GeV limit(+- 5mrad beam pipe hall)
Preliminary Conclusion Preliminary conclusion by a wild guess from a low stat. data
For Pt > 5GeV, Loss of efficiency of about 50% by putting cut on azimuthal angle.
The region below 5 GeV : will be hard to remove two-photon ee events
Plan Simulation of 1M events are in progress Hope result be ready by next week
Integrated luminosity
m(G
eV)
2
5 14mrad Xing
2mrad Xing
Stau search regionHeavy Mstau limit
m(G
eV)
Mstau
Excluded
14mrad
2mrad
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