Search for SUSY with Higgs in the final state · 2020. 9. 8. · Fake leptons Higgs Bkg. Uncert. 0)...
1
Motivations Based on “Naturalness”: lightest electro-weakinos expected to have mass of ∼O (100 GeV) ⇒ Direct electro-weakino and slepton production may dominate at the LHC energy! Signatures I ˜ χ ± 1 ˜ χ ∓ 1 and ˜ ˜ production ⇒ 2 leptons in final-states I ˜ χ ± 1 ˜ χ 0 2 production ⇒ 1 lepton 2 b -jets in final-states Lightest Supersymmetric Particle (LSP)⇒ missing transverse energy (E miss T ) Signal Model: Simplified Models I Cross sections are determined by the masses and composition of ˜ χ ± 1 and ˜ χ 0 2 , which are assumed to be wino-like. LSP assumed to be ˜ χ 0 1 . I ˜ χ ± 1 ˜ χ 0 2 production: BR( ˜ χ ± 1 → W ± ˜ χ 0 1 )=BR( ˜ χ 0 2 → h ˜ χ 0 1 )=1 ; BR(h → bb ) = SM-like ˜ χ ± 1 ˜ χ ∓ 1 and ˜ ˜ production ⇒ 2 leptons in final-states ˜ χ ± 1 ˜ χ ∓ 1 ˜ ‘/ ˜ ν ˜ ‘/ ˜ ν p p ν/‘ ‘/ν ˜ χ 0 1 ν/‘ ‘/ν ˜ χ 0 1 ˜ ‘ ˜ ‘ p p ˜ χ 0 1 l ˜ χ 0 1 l ˜ χ ± 1 ˜ χ ∓ 1 W W p p ˜ χ 0 1 ‘ ν ˜ χ 0 1 ‘ ν ˜ χ ± 1 ˜ χ 0 2 ⇒ 1l + 2 b -jets I m ˜ χ ± 1 = m ˜ χ 0 2 Signal selections in ˜ χ ± 1 ˜ χ ∓ 1 and ˜ ˜ ⇒ 2 leptons scenarios Sensitivity lepton flavour p 1 T p 2 T m p T, δφ E miss,rel. T m T2 SR-m T290 SR-m T2110 Slepton production e + e - , μ + μ - , e ± μ ∓ — — Z veto — — > 40 GeV > 90 GeV > 110 GeV SR-WWa SR-WWb SR-WWc Δm( ˜ χ ± 1 , ˜ χ 0 1 ) ∼ m W large Δm( ˜ χ ± 1 , ˜ χ 0 1 ) e ± μ ∓ > 35 GeV > 20 GeV < 80 GeV < 130 GeV — > 80 GeV < 170 GeV < 190 GeV < 1.8 rad > 70 GeV — — > 90 GeV > 100 GeV Stransverse mass m T2 = min q T max m T (p 1 T , q T ), m T (p 2 T , p miss T - q T ) Relative missing transverse energy E miss,rel. T = E miss T if Δφ ,j ≥ π /2 E miss T × sin Δφ ,j if Δφ ,j <π /2 Signal selections in ˜ χ ± 1 ˜ χ 0 2 ⇒ 1 lepton 2 b -jets scenarios Sensitivity Number of b -jets Jet kinematics Jet Veto Lepton E miss T m CT m bb m T SRA SRB Low Δm = m ˜ χ ± 1 , ˜ χ 0 2 - m ˜ χ 0 1 High Δm = m ˜ χ ± 1 , ˜ χ 0 2 - m ˜ χ 0 1 Exactly two b -tagged jets (MV1 @ 70%) b -tagged jets are leading jets No fourth-leading jet with p T > 25 GeV Exactly one signal and baseline lepton > 100 GeV > 160 GeV 105 < m bb < 135 GeV 100 < m T < 130 GeV > 130 GeV Contransverse mass m CT (v 1 , v 2 )= [E T (v 1 )+ E T (v 2 )] 2 - [p T (v 1 ) - p T (v 2 )] 2 Transverse mass m T = 2p lep T E miss T - 2p lep T · p miss T Background Estimates I A simultaneous fit of the control and signal regions is performed I Overall normalizations of main backgrounds are allowed to float, along with the signal strength to account for potential signal contamination in the control regions 2 leptons analysis 1 lepton 2 b -jets analysis Dominant WW , ZZ /ZW t ¯ t background (CR) top pair-production (t ¯ t ) W +jets Non-prompt leptons Matrix Method Higgs and others Monte Carlo simulations Dominant Jet energy resolution and scaling t ¯ t normalization systematic MC generator uncertainties (VV) Jet energy scale uncertainties (POWHEG vs Sherpa) Events / 5 GeV -1 10 1 10 2 10 3 10 4 10 Data 2012 WW + Wt t t Z+jets ZV Fake leptons Higgs MC Stat+Syst Uncert )=(140,20)GeV 0 1 χ ∼ ,m ± 1 χ ∼ (m )=(200,0)GeV 0 1 χ ∼ ,m ± 1 χ ∼ (m ATLAS Preliminary = 8 TeV s -1 Ldt = 20.3 fb ∫ channel μ e <1.8 ll φ <90GeV,d T2 >20GeV,m l2 T >35GeV,p l1 T nJets=0,p μ e [GeV] T2 m 0 20 40 60 80 100 120 Data/SM 0 0.5 1 1.5 2 [GeV] bb m Events 0 20 40 60 80 100 120 = 8 TeV s Data SM Total t t single top W+jets Z+jets +W/Z t t WW/WZ/ZZ WH ZH = 130, 0 GeV 1 0 χ , m 2 0 χ , 1 ± χ m = 225, 0 GeV 1 0 χ , m 2 0 χ , 1 ± χ m ATLAS Preliminary -1 L dt ~ 20.3 fb ∫ CR2 [GeV] bb m 0 50 100 150 200 250 300 350 400 Data/SM 0 0.5 1 1.5 2 2.5 Results for ˜ ˜ ⇒ 2 leptons in final-states SR-m T290 SR-m T2110 SR-WWa SR-WWb SR-WWc Expected back- ground 59.7±7.3 16.9±6.0 117.9±14.6 13.6±2.3 7.4±1.5 Observed 53 13 123 16 9 Expected σ 95 (fb) 1 +0.41 -0.28 0.62 +0.23 -0.16 1.77 +0.21 -0.15 0.51 +0.21 -0.15 0.37 +0.18 -0.11 Observed σ 95 (fb) 0.81 0.54 1.94 0.58 0.43 [GeV] miss,rel T E 50 100 150 200 250 300 Data / SM 0 0.5 1 1.5 2 Events / 20 GeV 2 4 6 8 10 Data 2012 WW + Wt t t Z+jets ZV Fake leptons Higgs Bkg. Uncert. ) = (251,10) GeV 0 1 χ ∼ ,m l ~ (m ) = (350,0) GeV 1 0 χ ∼ ,m 1 ± χ ∼ (m >90 GeV T2 >40 GeV, m miss,rel T ee nJets=0, Zveto, E =8 TeV s -1 L dt=20.3 fb ∫ ATLAS Preliminary Results ˜ χ ± 1 ˜ χ 0 2 ⇒ 1 lepton 2 b -jets in final-states [GeV] bb m Events 0 2 4 6 8 10 12 14 16 18 20 = 8 TeV s Data SM Total t t single top W+jets Z+jets +W/Z t t WW/WZ/ZZ WH ZH = 130, 0 GeV 1 0 χ , m 2 0 χ , 1 ± χ m = 225, 0 GeV 1 0 χ , m 2 0 χ , 1 ± χ m ATLAS Preliminary -1 L dt ~ 20.3 fb ∫ SRA [GeV] bb m 0 50 100 150 200 250 300 350 400 Data/SM 0 0.5 1 1.5 2 2.5 [GeV] bb m Events 0 2 4 6 8 10 12 14 16 18 20 = 8 TeV s Data SM Total t t single top W+jets Z+jets +W/Z t t WW/WZ/ZZ WH ZH = 130, 0 GeV 1 0 χ , m 2 0 χ , 1 ± χ m = 225, 0 GeV 1 0 χ , m 2 0 χ , 1 ± χ m ATLAS Preliminary -1 L dt ~ 20.3 fb ∫ SRB [GeV] bb m 0 50 100 150 200 250 300 350 400 Data/SM 0 0.5 1 1.5 2 2.5 Fit performed on m bb (invariant mass of the bb system) SRA SRB m bb bin Expected background 4 2 Observed (in m bb bin) 5.4 ± 3.1 2.1 ± 0.7 Asymptotic Observed σ 95 vis 0.32 fb 0.21 fb Observed S 95 obs 6.5 4.4 Expected S 95 exp 7.0 +3.1 -1.9 4.4 +2.5 -1.5 Pseudo experiments Observed σ 95 vis 0.34 fb 0.21 fb Observed S 95 obs 6.9 4.4 Expected S 95 exp 7.0 +2.8 -1.6 4.4 +1.8 -0.8 Exclusion limits No significant ex- cess has been ob- served in any of the signal regions I Using CLs method with asymptotic approximation I For each grid point: select SR with best expected limit Interpretation ˜ χ ± 1 ˜ χ ∓ 1 and ˜ ˜ ⇒ 2 leptons in final-states ) [GeV] ± 1 χ ∼ m( 0 100 200 300 400 500 ) [GeV] 0 1 χ ∼ m( 0 100 200 300 400 500 ) 0 1 χ ∼ )= m( ± 1 χ ∼ m( ) theory SUSY σ 1 ± Observed limit ( ) exp σ ± Expected limit ( ATLAS 7TeV (103.5GeV) 1 ± χ ∼ LEP2 ATLAS Preliminary =8 TeV s , -1 L dt = 20.3 fb ∫ 0 1 χ ∼ ν l × 2 → l) ν ∼ ( ν l ~ × 2 → - 1 χ ∼ + 1 χ ∼ = 0.5 1 0 χ ∼ - m ± 1 χ ∼ m 1 0 χ ∼ - m l ~ , ν ∼ m ) theory SUSY σ 1 ± Observed limit ( ) exp σ ± Expected limit ( ATLAS 7TeV (103.5GeV) 1 ± χ ∼ LEP2 All limits at 95% CL ) [GeV] l ~ m( 100 150 200 250 300 350 ) [GeV] 0 1 χ ∼ m( 0 50 100 150 200 250 ) 0 1 χ ∼ )= m( ± l ~ m( ) theory SUSY σ 1 ± Observed limit ( ) exp σ ± Expected limit ( excluded R μ ∼ LEP ATLAS Preliminary =8 TeV s , -1 L dt = 20.3 fb ∫ 0 1 χ ∼ - l 0 1 χ ∼ + l → - L,R l ~ + L,R l ~ ) theory SUSY σ 1 ± Observed limit ( ) exp σ ± Expected limit ( excluded R μ ∼ LEP All limits at 95% CL I m ˜ / ∈ [90,210] GeV (m ˜ χ 0 1 = 0) I m ˜ χ ± 1 / ∈ [130,450] GeV (m ˜ χ 0 1 = 20 GeV) ) [GeV] ± 1 χ ∼ m( 100 120 140 160 180 200 220 240 SUSY σ / σ 95% CL Limit on 1 10 ) = 0 GeV 0 1 χ ∼ m( ) SUSY theory σ 1 ± Observed limit ( ) exp σ 1 ± Expected limit ( -1 Ldt = 20.3 fb ∫ = 8 TeV: s ATLAS Preliminary ATLAS-CONF-2013-049 Interpretation ˜ χ ± 1 ˜ χ 0 2 ⇒ 1 lepton 2 b -jets Limits set on ˜ χ ± 1 / ˜ χ 0 2 mass (for m ˜ χ 0 1 = 0). 95% CL exclusion: I 125 < m ˜ χ ± 1 / ˜ χ 0 2 < 141 GeV I 166 < m ˜ χ ± 1 / ˜ χ 0 2 < 287 GeV at -1σ signal theoretical uncertainty. Expected exclusion range: I 225 < m ˜ χ ± 1 / ˜ χ 0 2 < 235 GeV ATLAS-CONF-2013-093 [GeV] 2 0 χ ∼ , 1 ± χ ∼ m 120 140 160 180 200 220 240 260 280 300 [GeV] 1 0 χ ∼ m 0 20 40 60 80 100 120 140 forbidden 1 0 χ ∼ + 0 h → 2 0 χ ∼ ATLAS Preliminary =8 TeV s , -1 L dt = 20.3 fb ∫ SRA+SRB 1 0 χ ∼ 0 h 1 0 χ ∼ ± W → 2 0 χ ∼ 1 ± χ ∼ Expected limit 68% CL ) theory SUSY σ 1 ± Observed limit ( ) exp σ 1 ± Expected limit (
Transcript of Search for SUSY with Higgs in the final state · 2020. 9. 8. · Fake leptons Higgs Bkg. Uncert. 0)...
Motivations
Based on “Naturalness”: lightest electro-weakinos expected tohave mass of ∼ O(100 GeV)⇒ Direct electro-weakino and slepton production may dominateat the LHC energy!
SignaturesI χ̃±1 χ̃
∓1 and ˜̀˜̀ production
⇒ 2 leptons in final-states
I χ̃±1 χ̃02 production
⇒ 1 lepton 2 b-jets in final-states
Lightest SupersymmetricParticle (LSP)⇒ missing transverse energy (E miss
T )
Signal Model: Simplified Models
I Cross sections are determined by the masses and composition of χ̃±1 and χ̃02, which are assumed to be wino-like. LSP assumed to be χ̃0
1.I χ̃±1 χ̃
02 production: BR(χ̃±1 → W± χ̃0
1)=BR(χ̃02 → h χ̃0
1)=1 ; BR(h→ bb) = SM-like
χ̃±1 χ̃∓1 and ˜̀˜̀ production ⇒ 2 leptons in final-states
χ̃±1
χ̃∓1
˜̀/ν̃˜̀/ν̃
p
p
ν/`
`/ν
χ̃01
ν/`
`/ν
χ̃01
˜̀
˜̀p
p
χ̃01
l
χ̃01
l
χ̃±1
χ̃∓1
W
Wp
p
χ̃01
`
ν
χ̃01
`
ν
χ̃±1 χ̃02 ⇒ 1 l + 2 b-jets
I mχ̃±1= mχ̃0
2
Signal selections in χ̃±1 χ̃∓1 and ˜̀˜̀⇒ 2 leptons scenarios
Sensitivitylepton flavour
p`1Tp`2Tm``
pT,``δφ``
Emiss,rel.T
mT2
SR-mT290 SR-mT2110Slepton production
e+e−, µ+µ−, e±µ∓
——
Z veto——
> 40 GeV> 90 GeV > 110 GeV
SR-WWa SR-WWb SR-WWc∆m(χ̃
±1 , χ̃
01) ∼ mW large ∆m(χ̃
±1 , χ̃
01)
e±µ∓
> 35 GeV> 20 GeV
< 80 GeV < 130 GeV —> 80 GeV < 170 GeV < 190 GeV
< 1.8 rad> 70 GeV —
— > 90 GeV > 100 GeV
Stransverse mass mT2 = minqT
maxmT(p`1T ,qT),mT(p`2T ,pmiss
T − qT)
Relative missing transverse energy Emiss,rel.T =
Emiss
T if ∆φ`,j ≥ π/2Emiss
T × sin ∆φ`,j if ∆φ`,j < π/2
Signal selections in χ̃±1 χ̃02 ⇒ 1 lepton 2 b-jets scenarios
SensitivityNumber of b-jets
Jet kinematicsJet Veto
LeptonEmiss
TmCTmbbmT
SRA SRBLow ∆m = mχ̃±1 ,χ̃
02−mχ̃0
1High ∆m = mχ̃±1 ,χ̃
02−mχ̃0
1Exactly two b-tagged jets (MV1 @ 70%)
b-tagged jets are leading jetsNo fourth-leading jet with pT > 25 GeVExactly one signal and baseline lepton
> 100 GeV> 160 GeV
105 < mbb< 135 GeV100 < mT< 130 GeV > 130 GeV
Contransverse mass mCT(v1, v2) =√√√√[ET(v1) + ET(v2)]2 − [pT(v1)− pT(v2)]2
Transverse mass mT =√√√√2plep
T EmissT − 2plep
T · pmissT
Background Estimates
I A simultaneous fit ofthe control and signalregions is performed
I Overall normalizationsof main backgroundsare allowed to float,along with the signalstrength to account forpotential signalcontamination in thecontrol regions
2 leptons analysis 1 lepton 2 b-jets analysisDominant WW , ZZ/ZW tt̄background (CR) top pair-production (t t̄) W +jetsNon-prompt leptons Matrix MethodHiggs and others Monte Carlo simulationsDominant Jet energy resolution and scaling t t̄ normalizationsystematic MC generator uncertainties (VV) Jet energy scaleuncertainties (POWHEG vs Sherpa)
Events
/ 5
GeV
110
1
10
210
310
410 Data 2012WW
+ WtttZ+jets
ZVFake leptonsHiggsMC Stat+Syst Uncert
)=(140,20)GeV0
1χ∼,m
±
1χ∼(m
)=(200,0)GeV0
1χ∼,m
±
1χ∼(m
ATLAS Preliminary
= 8 TeVs 1
Ldt = 20.3 fb∫ channel µe
<1.8ll
φ<90GeV,dT2
>20GeV,ml2
T>35GeV,p
l1
T nJets=0,pµe
[GeV]T2
m
0 20 40 60 80 100 120
Da
ta/S
M
00.5
1
1.52
[GeV]bbm
Events
0
20
40
60
80
100
120 = 8 TeVsData
SM Total
ttsingle topW+jetsZ+jets
+W/ZttWW/WZ/ZZWHZH
= 130, 0 GeV1
0χ, m
2
0χ,1
±χm = 225, 0 GeV
1
0χ, m
2
0χ,1
±χm
ATLAS Preliminary
1L dt ~ 20.3 fb∫
CR2
[GeV]bbm0 50 100 150 200 250 300 350 400D
ata
/SM
0
0.5
1
1.52
2.5
Results for ˜̀˜̀⇒ 2 leptons in final-states
SR-mT290 SR-mT2110 SR-WWa SR-WWb SR-WWcExpectedback-ground
59.7±7.3 16.9±6.0 117.9±14.6 13.6±2.3 7.4±1.5
Observed 53 13 123 16 9Expectedσ95 (fb) 1+0.41
−0.28 0.62+0.23−0.16 1.77+0.21
−0.15 0.51+0.21−0.15 0.37+0.18
−0.11
Observedσ95 (fb) 0.81 0.54 1.94 0.58 0.43
[GeV]miss,rel
TE
50 100 150 200 250 300
Data
/ S
M
00.5
11.5
2
Eve
nts
/ 2
0 G
eV
2
4
6
8
10Data 2012
WW
+ WtttZ+jets
ZV
Fake leptons
Higgs
Bkg. Uncert.
) = (251,10) GeV0
1χ∼,ml
~(m
) = (350,0) GeV1
0χ∼,m
1
±χ∼(m
>90 GeVT2
>40 GeV, mmiss,rel
Tee nJets=0, Zveto, E
=8 TeVs 1
L dt=20.3 fb∫ATLAS Preliminary
Results χ̃±1 χ̃02 ⇒ 1 lepton 2 b-jets in final-states
[GeV]bbm
Eve
nts
0
2
4
6
8
10
12
14
16
18
20
= 8 TeVsData SM Total
ttsingle topW+jetsZ+jets
+W/ZttWW/WZ/ZZWHZH
= 130, 0 GeV1
0χ, m
2
0χ,1
±χm = 225, 0 GeV
1
0χ, m
2
0χ,1
±χm
ATLAS Preliminary
1L dt ~ 20.3 fb∫
SRA
[GeV]bbm0 50 100 150 200 250 300 350 400D
ata
/SM
0
0.5
1
1.52
2.5 [GeV]bbm
Eve
nts
0
2
4
6
8
10
12
14
16
18
20
= 8 TeVsData SM Total
ttsingle topW+jetsZ+jets
+W/ZttWW/WZ/ZZWHZH
= 130, 0 GeV1
0χ, m
2
0χ,1
±χm = 225, 0 GeV
1
0χ, m
2
0χ,1
±χm
ATLAS Preliminary
1L dt ~ 20.3 fb∫
SRB
[GeV]bbm0 50 100 150 200 250 300 350 400D
ata
/SM
0
0.5
1
1.52
2.5
Fit performed on mbb(invariant mass of the bb system)
SRA SRB
mbb bin Expected background 4 2
Observed (in mbb bin) 5.4 ± 3.1 2.1 ± 0.7
Asy
mpt
otic Observed σ95
vis 0.32 fb 0.21 fbObserved S95
obs 6.5 4.4Expected S95
exp 7.0+3.1−1.9 4.4+2.5
−1.5
Pse
udo
expe
rimen
ts Observed σ95vis 0.34 fb 0.21 fb
Observed S95obs 6.9 4.4
Expected S95exp 7.0+2.8
−1.6 4.4+1.8−0.8
Exclusion limits
No significant ex-cess has been ob-served in any ofthe signal regionsI Using CLs method with
asymptotic approximationI For each grid point: select
SR with best expectedlimit
Interpretation χ̃±1 χ̃∓1 and ˜̀˜̀⇒ 2 leptons in final-states
) [GeV]±
1χ∼m(
0 100 200 300 400 500
) [G
eV
]0 1χ∼
m(
0
100
200
300
400
500
)0
1χ∼
)= m
(
±1χ∼
m(
)theory
SUSYσ1 ±Observed limit ()
expσ ±Expected limit (
ATLAS 7TeV (103.5GeV)
1
±χ∼LEP2
ATLAS Preliminary
=8 TeVs, 1
L dt = 20.3 fb∫
0
1χ∼ν l× 2 →l) ν∼(νl
~ × 2 →
1χ∼
+
1χ∼
= 0.5 1
0χ∼
m±
1χ∼
m
1
0χ∼
ml~,ν∼
m
)theory
SUSYσ1 ±Observed limit ()
expσ ±Expected limit (
ATLAS 7TeV (103.5GeV)
1
±χ∼LEP2
All limits at 95% CL
) [GeV]l~
m(
100 150 200 250 300 350
) [G
eV
]0 1χ∼
m(
0
50
100
150
200
250
)0
1χ∼ )=
m(
±l~
m(
)theory
SUSYσ1 ±Observed limit (
)exp
σ ±Expected limit (
excludedR
µ∼LEP
ATLAS Preliminary
=8 TeVs, 1
L dt = 20.3 fb∫
0
1χ∼
l
0
1χ∼ +
l→
L,Rl~
+
L,Rl~
)theory
SUSYσ1 ±Observed limit (
)exp
σ ±Expected limit (
excludedR
µ∼LEP
All limits at 95% CL
I m˜̀ /∈ [90,210] GeV (mχ̃01
= 0)I mχ̃±1
/∈ [130,450] GeV (mχ̃01
= 20 GeV)
) [GeV]±
1χ∼m(
100 120 140 160 180 200 220 240
SU
SY
σ/σ
95
% C
L L
imit o
n
1
10) = 0 GeV
0
1χ∼m(
)SUSY
theoryσ1 ±Observed limit (
)exp
σ1 ±Expected limit (
1Ldt = 20.3 fb∫ = 8 TeV: s
ATLAS Preliminary
ATLAS-CONF-2013-049
Interpretation χ̃±1 χ̃02 ⇒ 1 lepton 2 b-jets
Limits set on χ̃±1 /χ̃02 mass
(for mχ̃01
= 0). 95% CLexclusion:I 125 < mχ̃±1 /χ̃
02< 141 GeV
I 166 < mχ̃±1 /χ̃02< 287 GeV
at -1σ signal theoretical uncertainty.Expected exclusion range:I 225 < mχ̃±1 /χ̃
02< 235 GeV
ATLAS-CONF-2013-093 [GeV]2
0χ∼,
1
±χ∼
m120 140 160 180 200 220 240 260 280 300
[G
eV
]10
χ∼m
0
20
40
60
80
100
120
140
forb
idden
1
0χ∼
+
0 h
→2
0χ∼
ATLAS Preliminary
=8 TeVs, 1
L dt = 20.3 fb∫SRA+SRB
1
0χ∼0
h1
0χ∼± W→
2
0χ∼
1
±χ∼
Expected limit 68% CL
)theory
SUSYσ1 ±Observed limit (
)expσ1 ±Expected limit (
