Search For Supersymmetry In The Same Sign Gunn Kristine Holst Larsen
The Standard Model-Supersymmetry-ATLAS
Search For Supersymmetry In The Same Sign
Di-Lepton And One Lepton Channels
Gunn Kristine Holst Larsen
Supervisor: Farid Ould-Saada
University of Oslo
24th of October 2008
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Contents
1
The Standard Model-Supersymmetry-ATLAS
2
3
4
5
6
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
The Standard Model
•
•
•
Consistent renormalizable quantum field theory.
Based on Gauge symmetries
Explains data from a fraction of an eV to a few hundred GeV .
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Supersymmetry + examples of nice effects
•
•
•
Symmetry between fermions and bosons, Q a
Solution to the Hierarchy problem.
| J i = | J ± 1 / 2 i .
The Standard Model only explain ∼ 4% of the matter in the universe, Supersymmetry provides candidate for dark matter
( ∼ 21%).
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Supersymmetry + examples of nice effects
•
•
•
Symmetry between fermions and bosons, Q a
Solution to the Hierarchy problem.
| J i = | J ± 1 / 2 i .
The Standard Model only explain ∼ 4% of the matter in the universe, Supersymmetry provides candidate for dark matter
( ∼ 21%).
Quantum loop corrections to Higgs mass
•
•
−
| λ l
| 2
8 π 2
λ
B
16 π 2
Λ
Λ
2 cut
2 cut
+ ...
+ ...
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Supersymmetry + examples of nice effects
•
•
•
Symmetry between fermions and bosons, Q a
Solution to the Hierarchy problem.
| J i = | J ± 1 / 2 i .
The Standard Model only explain ∼ 4% of the matter in the universe, Supersymmetry provides candidate for dark matter
( ∼ 21%).
Conserved R-parity
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Supersymmetry + examples of nice effects
•
•
•
Symmetry between fermions and bosons, Q a
Solution to the Hierarchy problem.
| J i = | J ± 1 / 2 i .
The Standard Model only explain ∼ 4% of the matter in the universe, Supersymmetry provides candidate for dark matter
( ∼ 21%).
• Further interesting implications of Supersymmetry:
•
•
•
Possible Grand Unified Theory.
Connection to gravity.
Can be extrapolated all the way to the GUT or Planck scale.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
mSUGRA
•
•
•
No supersymmetric particles observed.
MSSM (Minimal Supersymmetric Standard Model) more than
100 free parameters.
mSUGRA 5 free parameters (Gravity communicates breaking and unification of scalar masses ( m
0
) and gaugino masses
( m
1 / 2
) at GUT scale is assumed.)
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
mSUGRA
•
•
•
No supersymmetric particles observed.
MSSM (Minimal Supersymmetric Standard Model) more than
100 free parameters.
mSUGRA 5 free parameters (Gravity communicates breaking and unification of scalar masses ( m
0
) and gaugino masses
( m
1 / 2
) at GUT scale is assumed.)
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
mSUGRA
•
•
•
No supersymmetric particles observed.
MSSM (Minimal Supersymmetric Standard Model) more than
100 free parameters.
mSUGRA 5 free parameters (Gravity communicates breaking and unification of scalar masses ( m
0
) and gaugino masses
( m
1 / 2
) at GUT scale is assumed.)
SU1 SU8.1
SU2 SU3 SU4 SU6
Coannihilation Focus Bulk Low mass Funnel m
0
[GeV] 70 m
1 / 2
[GeV]
A
0
350
0 tan( β ) 10 sign( µ ) +
210
360
0
40
+
3550
300
0
10
+
100
300
-300
6
+
200
160
-400
10
+
320
375
0
50
+
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
The Large Hadron Collider, LHC
•
•
•
•
Collide proton on proton to create new particles.
Luminosity: 10 34 cm − 2 s − 1 .
Center of mass energy: 14 TeV .
Observe phenomena at scale 10 − 18 m, conditions similar to universe 1ps after the Big Bang.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Detecting particles with ATLAS
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
We want to study the correct leptons!
• Monte Carlo simulated data → we know the truth.
•
•
Interested in physics from the hard interaction.
Must minimize leptons that are fake or stem from soft interactions .
Lepton type Decay mother
Primary (prompt) Z , W , SUSY, τ prompt
Secondary (other) all other (meson, baryon or fake lepton)
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Properties to distinguish primary and secondary leptons
• etcone20 of the lepton:
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
-5 0 5 10 15 20 25 30 35 40 etcone20 electron [GeV]
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
-5 0 5 10 15 20 25 30 35 40 etcone20 muon [GeV]
• etcone20= P
E
T (∆ R < 0 .
2)
• Angular distance ∆ R = p (( φ
1
− φ
2
) 2 + ( η
1
− η
2
) 2 ) where
η = − ln[tan( θ
2
)]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Properties to distinguish primary and secondary leptons
• etcone20 of the lepton:
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
-5 0 5 -5 10 15 20 25 30 35 40 etcone20 electron [GeV]
• Transverse momentum of the lepton:
0 5 10 15 20 25 30 35 40 etcone20 muon [GeV]
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
1
0 50 100 150 200 250 300 350 400 pt electron [GeV]
1
0 50 100 150 200 250 300 350 400 pt muon [GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Properties to distinguish primary and secondary leptons
• etcone20 of the lepton:
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
-5 0 5 10 15 20 25 30 35 40 etcone20 electron [GeV]
10
4
10
3
10
2
10
SU3 prime
SU3 sec
T1 prime
T1 sec
-5 0 5 10 15 20 25 30 35 40 etcone20 muon [GeV]
• Angular distance between lepton and closest jet.
•
•
Overlap removal electron jet. (∆ R
( e remove jet)
−
Jet )
<
Lepton angular distance to jet (∆ R
( e ,µ
−
Jet ) remove lepton)
0.2
<
→
0.4
→
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
• NORMetcone = etcone p
T
50
40
30
20
10
0
-10
0 100 200 300
SU3 prime
SU3 sec
SU3 prime
SU3 sec
400 500 600 p
T
electrons [GeV]
50
40
30
20
10
0
-10
0 100 200
50
40
30
20
10
0
-10
0 100 200 300 400
SU3 prime
SU3 sec
500 600 p
T
electrons
50
40
30
20
10
0
-10
0 100 200
300
300
SU3 prime
SU3 sec
SU3 prime
SU3 sec
400 500 600 p
T
muons [GeV]
400
SU3 prime
SU3 sec
500 600 p
T
muons
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Optimize calorimeter isolation cut
•
•
Efficiency ǫ p
=
Σprimary passing isolation cut
Σprimary
Rejection r s
= 1 −
Σsecondary passing isolation cut
Σsecondary
• ǫ p
: Electron
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
EtCone20/pt(lepton)
τ
primary mother
0.1
0.2
SU1
SU2
SU3
T1
0.3
0.4
0.5
Electrons: normalized etcone20
• ǫ p
: Muon
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0
EtCone20/pt(lepton)
τ
primary mother
0.1
0.2
SU1
SU2
SU3
T1
0.3
0.4
0.5
Muons: normalized etcone20
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Optimize calorimeter isolation cut
•
•
Efficiency ǫ p
=
Σprimary passing isolation cut
Σprimary
Rejection r s
= 1 −
Σsecondary passing isolation cut
Σsecondary
• r s
: Electron
0.7
0.6
0.5
0.4
0.3
1
0.9
0.8
SU1
SU2
SU3
T1
0
EtCone20/pt(lepton)
τ
primary mother
0.1
0.2
0.3
0.4
0.5
Electrons: normalized etcone20
• r s
: Muon
0.99
0.98
0.97
0.96
0.95
0.94
0
EtCone20/pt(lepton)
τ
primary mother
0.1
0.2
SU1
SU2
SU3
T1
0.3
0.4
0.5
Muons: normalized etcone20
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Optimize calorimeter isolation cut
•
•
Efficiency ǫ p
=
Σprimary passing isolation cut
Σprimary
Rejection r s
= 1 −
Σsecondary passing isolation cut
Σsecondary
• ǫ p
: Electron
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
EtCone20/pt(lepton)
τ
primary mother
0.1
0.2
SU1
SU2
SU3
T1
0.3
0.4
0.5
Electrons: normalized etcone20
• r s
: Electron
0.7
0.6
0.5
0.4
0.3
1
0.9
0.8
SU1
SU2
SU3
T1
0
EtCone20/pt(lepton)
τ
primary mother
0.1
0.2
0.3
0.4
0.5
Electrons: normalized etcone20
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Reward for finding the good leptons
•
•
M eff
= /
T
+ ΣJ et p
T
+ Σl epton p
T
Peak correlated with M
SUSY
= min ( m
˜
, m
˜
)
10
5
10
4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Reward for finding the good leptons
• M eff
• M eff
: one lepton
10
5
10
4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
10 4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
>1lep: M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Reward for finding the good leptons
• M eff
• M eff
: one isolated lepton
10
5
10
4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
10 4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
>1lep: M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Reward for finding the good leptons
• M eff
• M eff
: two leptons
10
5
10
4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
10
3
10 2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
>2lep: M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Reward for finding the good leptons
• M eff
• M eff
: two isolated leptons
10
5
10
4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
>2lep: M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Reward for finding the good leptons
• M eff
• M eff
: SS isolated leptons
10
5
10
4
10
3
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
10
2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
SS: M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Increased purity of the leptons
Base line selection:
#Lep 0 pr 1 pr 2 pr 3 pr 0 pr 1 pr 2 pr 3 pr
SU3 tt
1
2
3
0.06
0.94
-
0.00
0.06
0.93
-
0.03
0.00
0.97
0.19
-
0.79
-
-
0.00
0.01
0.11
0.87
0.00
0.18
0.66
0.15
Improved selection:
#Lep 0 pr 1 pr 2 pr 3 pr 0 pr 1 pr 2 pr 3 pr
1
2
3
SU3
0.04
0.96
-
0.00
0.03
0.97
-
-
0.00
0.00
0.056
0.94
tt
0.01
0.99
-
0.00
0.05
0.95
-
0 0.04
0.82
-
0.13
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Charge misidentification
• Invariant mass M ll
= p ( P E ) 2 + | P p | 2
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Charge misidentification
•
• Invariant mass M ll
= p ( P E ) 2 + | P p | 2
M ll
Same Sign • M ll
: Opposite Sign
100
80
60
40
20
Z->ll
8000
7000
6000
5000
4000
3000
2000
1000
0 0 50 100 150 200 250 300
SS lep: M ll
[GeV]
50
•
Z
( SS )
Z
( OS )
≃ 200
14000
≃ 0 .
014 → neglect able
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
100
Z->ll
150 200 250 300
OS lep: M ll
[GeV]
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Cut and Count → discover Supersymmetry
•
•
•
Robust method for search in early data.
Cut on variables that discriminate signal and background.
Significance √ b or √ S b + σ 2 syst
(one bin counting).
•
•
σ tot
= q
σ 2 stat
+ σ 2 syst
= q b + σ 2 syst
.
Systematic uncertainty in background estimate: Uncertainty in
W, Z and top estimated to 20 %, while 50% uncertainty is expected for QCD.
• Discovery when significance is bigger than five.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Background - Signal
•
•
1 lepton reduce QCD background.
Cross section for Same Sign leptons in the Standard Model is low. But the gluino (˜ ) is Majorana particle.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Background - Signal
•
•
1 lepton reduce QCD background.
Cross section for Same Sign leptons in the Standard Model is low. But the gluino (˜ ) is Majorana particle.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Missing transverse energy, /
T
•
•
Real /
T from neutrino ( ν ) and LSP ( ˜
0
1
)
No lepton selection.
10
6
10
5
10
4
10
3
10
2
10
SU2
SU3
SU4
SM bg
ATLAS Preliminary
1
0 100 200 300 400 500 600 700 800 900 1000
Missing E
T
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Missing transverse energy, /
T
•
•
Real /
T from neutrino ( ν ) and LSP ( ˜
0
1
)
One lepton selection.
10
4
10
3
10
2
10
SU1
SU2
SU3
SU4
SU6
SU8
SM bg
ATLAS Preliminary
1
0 100 200 300 400 500 600 700 800 900 1000
Missing E
T
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Missing transverse energy, /
T
•
•
Real /
T from neutrino ( ν ) and LSP ( ˜
0
1
)
Same Sign di-lepton selection.
10
3
10
2
10
SU1
SU2
SU3
SU4
SU6
SU8
SM bg
ATLAS Preliminary
1
0 100 200 300 400 500 600 700 800 900 1000
Missing E
T
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
δ Φ
2
Illustrate correlation
•
•
δφ
2
= | φ jet 2
− φ /
T
|
No lepton selection.
10
8
10
7
10
6
10
5
10
4
10
3
10
2
10
1
0 0.5
1 1.5
SM bg
ATLAS Preliminary
2
SU2
SU3
SU4
2.5
3 del
φ
2
[rad]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
δ Φ
2
Illustrate correlation
•
•
δφ
2
= | φ jet 2
− φ /
T
|
One lepton selection.
10
3
10
2
10
1
0 1 2
SU1
SU2
SU3
SU4
SU6
SU8
SM bg
ATLAS Preliminary
3 4 5 del
φ
2
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
δ Φ
2
Illustrate correlation
•
•
δφ
2
= | φ jet 2
− φ /
T
|
Same Sign di-lepton selection.
10
3
10
2
10
SU1
SU2
SU3
SU4
SU6
SU8
SM bg
ATLAS Preliminary
1
0 1 2 3 4 5 del
φ
2
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Cut on M
T
•
• m m
2
T
2
T
= 2
≤ m p l
T
2
W p
ν
T
(1 − cos
(generates a lower bound for the W mass on an event-by-event basis)
φ l ν
)
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
SU3 tt
W
Z
QCD
VV
ATLAS Preliminary
50 100 150 200 250 300
1 lepton: M ll
[GeV]
10
3
10 2
10
SU3 tt
W
Z
QCD
VV
ATLAS Preliminary
1
0 50 100 150 200 250 300
1 lepton: M ll
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
How to pick cut value?
25
20
15
10
5
40
35
30
100 150 200
SU1
SU2
SU3
SU6
SU8
250 300
E
T miss [GeV]
• To deal with correlations → multi variable scan to optimize significance.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
One lepton: cut selection from matrix optimization
•
•
•
•
•
•
•
•
• matrix of 4374 cut combinations
E
T
S
T
(100, 150, 200)
(0, 0.1, 0.2)
GeV jet1 p
T jet2 p
T jet3 p
T
(100, 150, 200)
(50, 100, 150)
(20, 50, 100)
GeV
GeV
GeV number of jets ( > =2, > =3, > =4)
δφ
1
(0, 0.2, 0.4)
E
T
/ M eff
(0, 0.2)
Cut
01
03
M eff
> 800
> 800 m
T
> 100
> 100
E
T
> 100
> 200
Jets
> =4
> =3 p jet 1
T
> 100
> 200 p jet 2
T
> 50
> 150 p jet 3
T
> 50
> 20 p jet 4
T
> 50
-
S
T
> 0.2
> 0.1
T
Meff
> 0.2
-
δφ
1
-
> 0.2
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Compare significance of one-lepton Cut03 to a four-jet base line cut
CUT
Cut01
Cut03
Cut01
Cut03
Cut01
Cut03
Cut01
Cut03
Cut01
Cut03
Cut01
Cut03
S
241.8
492.4
41.3
46.8
380.1
623.6
847.7
1092.9
156.8
268.5
142.5
257.8
B S /
√ b
SU1
42.0
50.3
SU2
37.3
69.3
42.0
50.4
SU3
42.0
50.3
6.3
6.6
58.6
87.8
42.0
50.3
SU4
SU6
130.7
153.9
42.0
50.4
24.2
37.8
SU8
42.0
50.3
21.9
36.3
S / q b + σ
2 syst
23.7
40.4
4.0
3.8
37.3
51.2
83.3
89.8
15.4
22.1
14.0
21.1
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Same Sign di-lepton cut selection
•
•
•
• matrix of 8 cut combinations
E
T
(100,130) GeV number of jet ( > 2, > 3) p
T of hardest lepton (100,130) GeV
Cut01
Cut07 /
T
E
T
jets -
> 130 GeV jets > 2 p
T p
T jet
1 jet
1
-
> 130 GeV
Signal
SU1
SU2
SU3
SU4
SU6
SU8
CUT
Cut01
Cut07
Cut01
Cut07
Cut01
Cut07
Cut01
Cut07
Cut01
Cut07
Cut01
Cut07
B
42.2
16.6
42.2
16.6
42.2
16.6
42.2
16.6
42.2
16.6
42.2
16.6
S
88.8
81.6
20.9
17.7
142.9
124.7
904.7
559.1
47.5
43.6
32.0
28.5
S
√ B
13.6
19.9
3.2
4.3
21.9
30.5
139.1
136.8
7.3
10.6
4.9
7.0
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
S q
B +
σ
2 syst
8.3
15.4
1.9
3.3
13.3
23.6
84.7
106.0
4.4
8.8
2.9
5.4
University of Oslo
The Standard Model-Supersymmetry-ATLAS
One lepton and Same Sign lepton selection
• Same Sign ONLY • One lepton ONLY
10 2
10
SU3 tt
W
Z
QCD
VV sum bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
SS: M eff
[GeV]
10
4
10
3
10
2
10
SU1
SU2
SU3
SU4
SU6
SU8
SM bg
ATLAS Preliminary
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
One lepton and Same Sign lepton selection
• Same Sign + Cut07 • One lepton + Cut03
10 3
10 2
10
SU2
SU3
SU4
SM bg
ATLAS Preliminary
10 3
10 2
10
SU1
SU2
SU3
SU4
SU6
SU8
SM bg
ATLAS Preliminary
1
0
•
•
500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
1
0 500 1000 1500 2000 2500 3000 3500 4000
M eff
[GeV]
All points can be discovered!
σ > 5 .
SU2 just at the limit in the one-lepton channel.
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Conclusion
• By studying lepton isolation it is possible to get a more pure lepton selection in the events.
• However this is simulated data, and real data might behave differently.
• If Supersymmetry is realized in nature in a region of parameter space with similar phenomenology as any of the studied mSUGRA points, ATLAS will be able to make a discovery already with 1 fb
− 1 of data.
•
•
•
Assumed perfectly understood detector.
Trigger must be taken into account.
•
Now the work to align and calibrate the detector is about to start.
Soon we will have answers from the machine that make us dream!
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
The Standard Model-Supersymmetry-ATLAS
Work at CERN
•
•
• Data Quality shift
•
•
•
Milestone 5
Pre-beam test
Milestone 8
Static Web Page for the SCT DCS
SCT End-Cap Installation
Search For Supersymmetry In The Same Sign Di-Lepton And One Lepton Channels
University of Oslo
