1.  WW / ZZ separation Some clarification on
how the main background is rejected
how the detector performances are involved
J.C. BRIENT

2. Starting point Mass J3 J4 (GeV) Mass J1 J2 (GeV) ∆EJ = 0.60 EJ
Simulation with
Simulation with
Mass J3 J4 (GeV)
Starting point
Mass J1 J2 (GeV)
This presentation
Add background e±  W∓
Effect when using the VDET btag
Quantify the results with S/N ratio for different searches
J.C. BRIENT

3. ZZ, WW, eWZ,  Select 4 jets ∆EJ = 0.30 EJ Simulation with 4 1245
Cross sections (fb)
ZZ, WW, eWZ,
Mass J3J4 (GeV)
Mass J1J2 (GeV)
∆EJ = 0.30 EJ
Simulation with
J.C. BRIENT

4. ZZ, WW, eWZ, With all decays to jets.
Processes
ZZ, WW, eWZ, With all decays to jets.
In the fiducial volume of the detector, an isolated electron with high energy
is a good tagging for process (3)
ALL processes
Process (3)
Electron energy (GeV)
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5. Reject if The low angle coverage for electron is ESSENTIAL
Electron Energy >100GeV (50 at low angle)
MM2<500 and Electron Energy >5GeV
MM2<250 and Electron Energy >2.5GeV
The low angle coverage
for electron is
ESSENTIAL
process e+ e− → e±  W∓ Z (blue)
almost disappears, while leaving processes (1) and (2) unchanged
Mass J3 J4 (GeV)
Mass J1 J2 (GeV)
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6. ≈ 12.2 Select ≥ 2 b-jets Mass J3 J4 (GeV) Mass J1 J2 (GeV) S(ZZ)
B(WZ,WW)
≈ 12.2
Mass J3 J4 (GeV)
Mass J1 J2 (GeV)
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7. ≈ 100 ≈ 18.6 ≈ 2.4 Select < 2 b-jets After cut
Before di-jet mass cut
S(WW,ZZ)
B(WZ)
≈ 100
After cut
WW region:
Contains 89 % of the WW and
S(WW)
B(ZZ, WZ)
≈ 18.6
ZZ region:
Contains 71 % of the ZZ
S(ZZ)
B(WW, WZ)
≈ 2.4
J.C. BRIENT

8. e±  W∓ background can be removed easily
Other relevant backgrounds seem easier to remove (guess)
i.e. WW, Z() could be rejected with missing energy and mass
e±  W∓ background can be removed easily
(with a good electron id. at low angle )
the main problem is still the WW/ZZ separation
For ZZ rejection, a good VDET btag can help
the PFLOW performance is still the key point for the analysis
J.C. BRIENT