Transcript Trileptons @ CDF

Search for
Chargino and Neutralino in
the low pT eμ channel
-- STATUS -Melisa Rossi
Udine University
December 18, 2006
SUSY Meeting
1
Last time

Low MET region is our challenge ...

Most likely our bbbar does NOT provide
suitable description of HF contribution
 Assuming our bbbar MC has appropriate
kinematics, need a new renormalization...
 Following the method of New Mexico

December 18, 2006
Stripping data reversing d0 cut on muons
SUSY Meeting
2
Last time

Get new bbbar normalization for bbbar MC

Fitting (HF + OtherBackgrounds) to Data
OLD bb norm
Opposite Sign
NEW bb norm
December 18, 2006
SUSY Meeting
3
Since Last Time

Re-checked lepton selection



Now sliding isolation cut only for high pT
leptons
More bbbar MC statistics
 Last time 140 pb-1  Now 350 pb-1
Extracted Heavy Flavor enriched sample
from data following the NM method
December 18, 2006
SUSY Meeting
4
Get bbbar MC normalization
USING MORE (350pb-1) bbbar STATISTICS




Freezing HF shape from bbbar MC including b mixing
Normalizing all other backgrounds as usual
Fitting (HF + OtherBackgrounds) invariant mass distribution to Data
Treating OS and SS separately
NEW bb norm
for OS eμ events
December 18, 2006
NEW bb norm
for LS eμ events
SUSY Meeting
5
eμ distributions
NEW bb norm
for OS eμ events
December 18, 2006
NEW bb norm
for LS eμ events
SUSY Meeting
6
eμ Low MET Region
MET<10 GeV nJET<2
NEW bb norm
for OS eμ events
NEW bb norm
for LS eμ events
December 18, 2006
SUSY Meeting
7
Heavy Flavor a la NM

Filtered edil0d (250 pb-1) requiring at least 1 μ
with d0 cut inverted.
December 18, 2006
SUSY Meeting
8
Heavy Flavor a la NM

Invariant Mass and MET eμ and μμ distributions
December 18, 2006
SUSY Meeting
9
Heavy Flavor a la NM

Selection of eμ and μμ events
1 lepton with pT>10GeV/c
263
1 lepton with pT>10GeV/c
42508
nVertex12>0
262
nVertex12>0
12308
DeltaZ(lep1,lep2)
<4cm
226
DeltaZ(lep1,lep2)
<4cm
2574
InvMass>15 GeV/c2
142
acollinearity<3.1
291
Coscmic Filter
(HasNotOutgoingPair)
142
InvMass>15 GeV/c2
166
108
DeltaR(lep1,lep2)>0.4
142
Coscmic Filter
(HasNotOutgoingPair)
DeltaR(lep1,lep2)>0.4
108
December 18, 2006
SUSY Meeting
10
Heavy Flavor a la NM

Acollinearity for μμ events
1 lepton with pT>10GeV/c
42508
nVertex12>0
12308
DeltaZ(lep1,lep2)
<4cm
2574
acollinearity<3.1
291
InvMass>15 GeV/c2
166
Coscmic Filter
(HasNotOutgoingPair)
108
DeltaR(lep1,lep2)>0.4
108
.... Few statistics w.r.t John since my selection is different
• using 250 pb-1
• only CMUP_CMUP dimuon events
• requiring leading muon pT> 10 GeV/c
• requiring InvMass > 15 GeV/c2
December 18, 2006
SUSY Meeting
11
Conclusions



Double bbbar improved substantially
agreement in the Low MET Region.
Reasonably demonstrated that the Low
MET region is dominated by HF.
Extracted HF sample from data similarly to
John

Need to see if enough statistics in the eμ events
to make a reasonable (HF + otherBG) fit to data
December 18, 2006
SUSY Meeting
12
Data and MC

Data

SUSY dilepton dataset edil0d


MC








Good run list v7 no silicon (~310pb-1), CEM4_CMUP4 trigger
Signal point (m0=100,m1/2=180,A0=0,tanβ=5,μ>0) ~360fb-1
DY sexo9t (Z ll, Mll>5GeV/c2) ~5fb-1
ttbar (ttopel) ~170fb-1
WW (wtop1w) ~34fb-1
ZZ (Oscar) ~535fb-1
WZ (Madgraph) ~430fb-1
bbbar (Giovanni) ~350pb-1
Fakes


using CEM8 and CMUP8 inclusive samples
Lepton+fake selection requiring events with


real first lepton (CEM8 for eμ and CMUP8 for μe)
fake lepton using Liverpool method
December 18, 2006
SUSY Meeting
13