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Searches for squarks and gluinos in all-hadronic final states with ATLAS
Koichi NAGAIUniversity of Oxford
On behalf of ATLAS collaboration
SUSY 17
National Organising Committee Sudeshna Banerjee Gautam Bhattacharyya Utpal Chattopadhaya Anindya Datta Rajesh Gopakumar Monoranjan Guchait (Convenor) Gobinda Mazumdar Biswarup Mukhopadhaya Sudhakar Panda Anjan Ananda Sen Seema Sharma K. Sridhar Raghavan Rangarajan Sreerup Raychaudhuri (Co-Convenor) V. Ravindran Sudhir Vempati
Important Dates Early registration: Aug 1 – Oct 20, 2017 Late registration:
Oct 21 – Nov 3, 2017
Website: http://www.tifr.res.in/~susy17/
Contact: susy17@tifr.res.in
International Advisory Committee Ignatios Antoniadis
Csaba Balazs Wim de Boer Marcela Carena
Mirjam Cvetic Athanasios Dedes Keith Dienes
Herbi Dreiner John Ellis
Jonathan L. Feng Gian F. Giudice Rohini M Godbole
Kaoru Hagiwara Tao Han
Gordon L. Kane Jihn E. Kim
Pyungwon Ko Paul G. Langacker
Joseph D. Lykken Rabindra N. Mohapatra
Pran Nath Apostolos Pilaftsis
Fernando Quevedo Graham G. Ross
Sandip Trivedi
December 11 – 15, 2017
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
ATLAS in LHCLarge Hadron Collider (LHC) has been successfully operated at √s = 13 TeV.
A total integrated luminosity of 36.1 fb—1 of proton-proton collision data was collected by the ATLAS experiment with good detector conditions and data quality during 2015 and 2016.
2
Upgrade of ATLAS detector before 13 TeV data taking to improve sensitivity:➡ Insertable B-Layer
(Ave. 3 cm from the beam axis)✓ improved tracking, especially b-tagging
➡ ATLAS High Level Trigger system✓ larger acceptance, while enhancing
rejection๏ Improved ET
miss trigger๏ Improved jet energy scale
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
SUSY production at LHCSupersymmetry (SUSY) is an extension of Standard Model (SM)
• A solution of hierarchy problem
Assuming R-parity is conserved (RPC),• SUSY particles are pair-produced• Decay to SM particles and the lightest SUSY
particle (LSP).• LSP is stable and weakly interacting.
➡ Missing transverse momentum: ET miss
At LHC, a pair of SUSY particles can be dominantly produced with strong interactions.
• large cross-sections for gluino and squark productions
3
7XVSRK 4VSHYGXMSR
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�/��
Eur.Phys.J. C74 (2014) 12, 3174 LHC cross-section working group
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Search channels
4
Searches for 3rd generations are in another talks
squarks/gluinos pair productions+
full hadronic decaysRPC0 lepton
Multi-jets
g̃
g̃
!̃02
!̃±1
p
p
t t
!̃01
Z/h
tb
!̃01
W
Many-step
pMSSM
2-6 jets
1 stepDirect
Gtt/Gbb
Gtt
Gbb
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Search strategies
5
Control Regions (CR)• Orthogonal to SR, small
contamination of signals • Enriched a particular BKG• Evaluate BKG MCs' normalisation
factors with BKG only fit
Signal Regions (SR)• Many dedicated SRs constructed by
target signatures using discriminating variables, for example,
• ET miss, Njet, Nb-jets, pT
Jet, MEFF, MJ ∑,
ET miss/√HT, ISR Jet, (➝
pT
jet, ➝ ET miss)min
• Event level variables by Recursive Jigsaw Reconstruction (RJR)
Targets of searches • “Simplified Model”✓ 1 step✓ Many-step✓ Gtt, Gbb
• particular decay modes✓ phenomenological MSSM
(pMSSM)
Validation Regions (VR)
• Close to SR, limited potential signal contamination
• Validate background modelling
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
2-6jets channel
6
squarks/gluinos pair productions+
full hadronic decaysRPC0 lepton
Searches for 3rd generations are in another talks
Multi-jets
g̃
g̃
!̃02
!̃±1
p
p
t t
!̃01
Z/h
tb
!̃01
W
Many-step
pMSSM
2-6 jets
1 stepDirect
Gtt/Gbb
Gtt
Gbb
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
RJR-based search• 19 SRs:
➡ Δm ≡ mP−mI
➡ squark/gluino/compressed decay models
➡ RJR-variables defined by decay models
2-6j: Search strategies
7
https://arxiv.org/abs/1712.02332
LAB
CM
ISR SV I
Lab State
Decay States
Visible States
Invisible States
Compressed
1 stepDirec
Effective mass (MEFF)-based search• MEFF ≡ ∑pT
Jet + ET miss
✓ MEFF ≈ parent sparticle mass• 24 SRs: sparticle mass and final states
➡ ≧ 2, 3, 4, 5 jets: direct decays to LSP➡ ≧ 5,6 jets: 1 step cascade decay with
hadronically decaying W/Z/h bosons➡ ≧ 2 re-clustered large-R jets (R=1.0):
1 step cascade decay with boosted W/Z/h bosons
&m
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
2-6j: Background Estimation
8
Z + jets Z→νν CR with γ + jetsW + jets W→lν CR with 1 lepton + b-jet vetoTop quark pair Semi-leptonic
decays CR with 1 lepton + b-jet taggingsingle top
Semi-leptonic decays CR with 1 lepton + b-jet tagging
di-boson production MC normalised to NLO cross-section
QCD multi-jet a data driven method with jet smearing
[GeV]CMT S
p200 400 600 800 1000 1200 1400 1600 1800 2000
Even
ts /
200
GeV
1
10
210
310
410
510
610
710 ATLAS -1=13 TeV, 36.1 fbs
for RJR-C1aCR
Data 2015 and 2016
SM Total
+jetsa
W+jets
(+EW) & single toptt
Z+jets
Diboson
[GeV]CMT S
p200 400 600 800 1000 1200 1400 1600 1800 2000
Dat
a / M
C
00.5
11.5
2
Even
ts /
200
GeV
1
10
210
310
410 ATLAS
-1=13 TeV, 36.1 fbsCRT for Meff-4j-2200
Data 2015 and 2016SM Total
(+EW) & single topttW+jetsZ+jetsDibosonMulti-jet
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C
00.5
11.5
2
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
RJR Signal RegionRJR
-C1
RJR
-C2
RJR
-C3
RJR
-C4
RJR
-C5
RJR
-G1a
RJR
-G1b
RJR
-G2a
RJR
-G2b
RJR
-G3a
RJR
-G3b
RJR
-G4
RJR
-S1a
RJR
-S1b
RJR
-S2a
RJR
-S2b
RJR
-S3a
RJR
-S3b
RJR
-S4
Even
ts
1
10
210
310
410
510Data 2015 and 2016SM TotalW+jets(+EW) & single toptt
Z+jetsDibosonMulti-jet
ATLAS-1=13TeV, 36.1 fbs
RJR Signal RegionR
JR-C
1
RJR
-C2
RJR
-C3
RJR
-C4
RJR
-C5
RJR
-G1a
RJR
-G1b
RJR
-G2a
RJR
-G2b
RJR
-G3a
RJR
-G3b
RJR
-G4
RJR
-S1a
RJR
-S1b
RJR
-S2a
RJR
-S2b
RJR
-S3a
RJR
-S3b
RJR
-S4
Dat
a/SM
Tot
al0
0.51
1.5
2
2j-1
200
2j-1
600
2j-2
000
2j-2
100
2j-2
400
2j-2
800
2j-3
600
2jB-
1600
2jB-
2400
3j-1
300
4j-1
000
4j-1
400
4j-1
800
4j-2
200
4j-2
600
4j-3
000
5j-1
600
5j-1
700
5j-2
000
5j-2
600
6j-1
200
6j-1
800
6j-2
200
6j-2
600
Meff Signal Region
1
10
210
310
410
Even
ts
Data 2015 and 2016SM TotalW+jets(+EW) & single toptt
Z+jetsDibosonMulti-jet
ATLAS-1=13TeV, 36.1 fbs
2j-1
200
2j-1
600
2j-2
000
2j-2
100
2j-2
400
2j-2
800
2j-3
600
2jB-
1600
2jB-
2400
3j-1
300
4j-1
000
4j-1
400
4j-1
800
4j-2
200
4j-2
600
4j-3
000
5j-1
600
5j-1
700
5j-2
000
5j-2
600
6j-1
200
6j-1
800
6j-2
200
6j-2
600
Meff Signal Region
00.5
11.5
2
Dat
a/SM
Tot
al
2-6j: ResultsNo significant excess
The largest excesses are 2 × 2.0σ in MEFF and 2.5σ RJR(red circles)
9
MEFF RJR
squark1step boosted
gluino 1 step Compressedgluino
squark
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
2-6j: Interpretations
•Exclusion limit obtained with the SR with the best expected sensitivity at each mass point
10
[GeV]q~m400 600 800 1000 1200 1400 1600 1800
[GeV
]0 1χ∼
m
0
200
400
600
800
1000
1200
1400
01χ∼ < m
q~m
)=100%01χ∼ q → q~(B production, q~q~
ATLAS-1 = 13 TeV, 36.1 fbs
0-leptons, 2-6 jets
MEff or RJR (Best Expected)All limits at 95% CL
)c~,s~,d~,u~ (R
q~+L
q~
)SUSYtheoryσ1 ±Obs. limit (
)expσ1 ±Exp. limits (Exp. limits MEffExp. limits RJR
)-10L obs. limit (13 TeV, 3.2 fb
[GeV]g~m500 1000 1500 2000 2500
[GeV
]0 1χ∼
m
0
200
400
600
800
1000
1200
1400
1600
1800
01χ∼
< m
g~m
)=100%01χ∼ qq → g~(B production, g~g~
ATLAS-1 = 13 TeV, 36.1 fbs
0-leptons, 2-6 jets
MEff or RJR (Best Expected)All limits at 95% CL
)SUSYtheoryσ1 ±Obs. limit (
)expσ1 ±Exp. limits (Exp. limits MEffExp. limits RJR
)-10L obs. limit (13 TeV, 3.2 fb
[GeV]g~m1000 2000 3000 4000 5000 6000
[GeV
]q~
m
1000
2000
3000
4000
5000
6000)=0 GeV0
1χ∼Squark-gluino-neutralino model, m(
ATLAS-1 = 13 TeV, 36.1 fbs
0-leptons, 2-6 jetsAll limits at 95% CL
Meff or RJR (Best Expected)
)c~,s~,d~,u~ (R
q~+L
q~
)SUSYtheoryσ1 ±0L obs. limit (
)expσ1 ±Exp. limits (
)-1Observed limit (8 TeV , 20.3 fb
Squark production
Gluino mass
Gluino production
Squa
rk m
ass
Squark mass
LSP
mas
s
Gluino mass
LSP
mas
s
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
[GeV]q~m400 600 800 1000 1200 1400 1600 1800
[GeV
]0 1χ∼
m
0
200
400
600
800
1000
1200
1400
01χ∼ < m
q~m
)=100%01χ∼ q → q~(B production, q~q~
ATLAS-1 = 13 TeV, 36.1 fbs
0-leptons, 2-6 jets
MEff or RJR (Best Expected)All limits at 95% CL
)c~,s~,d~,u~ (R
q~+L
q~
)SUSYtheoryσ1 ±Obs. limit (
)expσ1 ±Exp. limits (Exp. limits MEffExp. limits RJR
)-10L obs. limit (13 TeV, 3.2 fb
[GeV]g~m500 1000 1500 2000 2500
[GeV
]0 1χ∼
m
0
200
400
600
800
1000
1200
1400
1600
1800
01χ∼
< m
g~m
)=100%01χ∼ qq → g~(B production, g~g~
ATLAS-1 = 13 TeV, 36.1 fbs
0-leptons, 2-6 jets
MEff or RJR (Best Expected)All limits at 95% CL
)SUSYtheoryσ1 ±Obs. limit (
)expσ1 ±Exp. limits (Exp. limits MEffExp. limits RJR
)-10L obs. limit (13 TeV, 3.2 fb
[GeV]g~m1000 2000 3000 4000 5000 6000
[GeV
]q~
m
1000
2000
3000
4000
5000
6000)=0 GeV0
1χ∼Squark-gluino-neutralino model, m(
ATLAS-1 = 13 TeV, 36.1 fbs
0-leptons, 2-6 jetsAll limits at 95% CL
Meff or RJR (Best Expected)
)c~,s~,d~,u~ (R
q~+L
q~
)SUSYtheoryσ1 ±0L obs. limit (
)expσ1 ±Exp. limits (
)-1Observed limit (8 TeV , 20.3 fb
2-6j: Interpretations
•Exclusion limit obtained with the SR with the best expected sensitivity at each mass point
•RJR-based SRs improved limits in regions with very compressed spectra
11
Squark production
Gluino mass
Gluino production
Squa
rk m
ass
Squark mass
LSP
mas
s
Gluino mass
LSP
mas
s RJR-Gluino
RJR-CompressedRJR-Compressed
RJR-Squark
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Gtt/Gbb channel
12
Searches for 3rd generations are in another talks
squarks/gluinos pair productions+
full hadronic decaysRPC0 lepton
Multi-jets
g̃
g̃
!̃02
!̃±1
p
p
t t
!̃01
Z/h
tb
!̃01
W
Many-step
pMSSM
2-6 jets
1 stepDirect
Gtt/Gbb
Gtt
Gbb
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Gtt/Gbb: IntroductionA search for gluino mediated stop (Gtt)/sbottom (Gbb) productions
• Masses of stop and sbottom are expected to be light to solve the hierarchy problem.
SRs are built by considering event signatures:• Njet ≥ 4 with pT
Jet ≥ 30 GeV
• Nb-jet ≥ 3• Large ET
miss
• ΔM = ⎮Mgluino − MLSP⎮
• MEFF ≡ ∑pT Jet + ∑pT
Lepton + ET miss
For Gtt, followings are also considered• Massive reclustered large-R jet (R=0.8) due to boosted top • Isolated e± or μ± from semi-leptonic top decay
13
https://arxiv.org/abs/1711.01901
Cut-and-count• Maximise discovery power• 6 Gtt & 4 Gbb SRs:
Based on ΔM✓ four &M regions: High,
Moderate, Low, Very low✓ partially overlapping
Multi-bin• Strengthen the exclusion
limit• 14 SRs:
Based on MEFF and Njet✓ non-overlapping
Gtt/Gbb
Gtt
Gbb
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Gtt/Gbb: Background Estimation
14
VR0L_IStR_Gtt
VR0L_Lnj_Lmeff_Gtt
VR0L_Lnj_Imeff_Gtt
VR0L_Lnj_Hmeff_Gtt
VR0L_Inj_Lmeff_Gtt
VR1LmT_Inj_Lmeff_Gtt
VR0L_Inj_Imeff_Gtt
VR1LmT_Inj_Imeff_Gtt
VR0L_Hnj_Lmeff_Gtt
VR1LmT_Hnj_Lmeff_Gtt
VR0L_Hnj_Imeff_Gtt
VR1LmT_Hnj_Imeff_Gtt
VR0L_Hnj_Hmeff_Gtt
VR1LmT_Hnj_Hmeff_Gtt
Even
ts
1
10
210
310 Data Total backgroundtt Single top + Xtt W+jets
Z+jets DibosonMultijetMulti-bin analysis
-1=13 TeV, 36.1 fbsATLAS
VR-0L-ISRVR-0L-LL
VR-0L-LIVR-0L-LH
VR-0L-ILVR-1L-IL
VR-0L-IIVR-1L-II
VR-0L-HLVR-1L-HL
VR-0L-HIVR-1L-HI
VR-0L-HHVR-1L-HH
tot
σ) /
pr
ed -
nob
s(n
2−02
VR1_Gtt_1l_A
VR2_Gtt_1l_A
VR1_Gtt_1l_B
VR2_Gtt_1l_B
VR1_Gtt_1l_C
VR2_Gtt_1l_C
VR2_Gtt_0l_A
VR2_Gtt_0l_B
VR2_Gtt_0l_C
VR2_Gbb_AVR2_Gbb_D
VR2_Gbb_BVR2_Gbb_C
Even
ts
1
10
210
310 Data Total backgroundtt Single top + Xtt W+jets
Z+jets DibosonMultijetCut-and-count analysis
-1=13 TeV, 36.1 fbsATLAS
-Gtt-1L-BT
VR-m-Gtt-1L-B
b-jetsT,min
VR-m -Gtt-1L-MT
VR-m-Gtt-1L-M
b-jetsT,min
VR-m -Gtt-1L-CT
VR-m-Gtt-1L-C
b-jetsT,min
VR-m VR-Gtt-0L-BVR-Gtt-0L-M
VR-Gtt-0L-CVR-Gbb-B
VR-Gbb-MVR-Gbb-C
VR-Gbb-VC
tot
σ) /
pr
ed -
nob
s(n
2−02
top quark pair MC normalised with top quark pair CRsingle top, 4 tops
MC normalised to the best available cross-section
Z + jets Z→ννMC normalised to the best available cross-section W + jets W→lν MC normalised to the best available cross-section
Top quark pair + W/Z/h
MC normalised to the best available cross-section
di-boson production
MC normalised to the best available cross-section
QCD multi-jet a data driven method with jet smearing
Cut-and-count VRs Multi-bin VRs
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Gtt/Gbb: Results
No significant excess
The largest excess ≈ 2.3σ in a Multi-bin SR
15
SR_Gtt_1l_ASR_Gtt_1l_B
SR_Gtt_1l_CSR_Gtt_0l_A
SR_Gtt_0l_BSR_Gtt_0l_C
SR_Gbb_ASR_Gbb_D
SR_Gbb_BSR_Gbb_C
Even
ts
1−10
1
10
210
310Data Total backgroundtt Single top + Xtt W+jets
Z+jets DibosonMultijetCut-and-count analysis
-1=13 TeV, 36.1 fbsATLAS
SR-Gtt-1L-BSR-Gtt-1L-M
SR-Gtt-1L-CSR-Gtt-0L-B
SR-Gtt-0L-MSR-Gtt-0L-C
SR-Gbb-BSR-Gbb-M
SR-Gbb-CSR-Gbb-VC
tot
σ) /
pr
ed -
nob
s(n
2−02
SR_0l_IStR_Gtt
SR_0l_Lnj_Lmeff_Gtt
SR_0l_Lnj_Imeff_Gtt
SR_0l_Lnj_Hmeff_Gtt
SR_0l_Inj_Lmeff_Gtt
SR_1l_Inj_Lmeff_Gtt
SR_0l_Inj_Imeff_Gtt
SR_1l_Inj_Imeff_Gtt
SR_0l_Hnj_Lmeff_Gtt
SR_1l_Hnj_Lmeff_Gtt
SR_0l_Hnj_Imeff_Gtt
SR_1l_Hnj_Imeff_Gtt
SR_0l_Hnj_Hmeff_Gtt
SR_1l_Hnj_Hmeff_Gtt
Even
ts
1−10
1
10
210
310Data Total backgroundtt Single top + Xtt W+jets
Z+jets DibosonMultijetMulti-bin analysis
-1=13 TeV, 36.1 fbsATLAS
SR-0L-ISRSR-0L-LL
SR-0L-LISR-0L-LH
SR-0L-ILSR-1L-IL
SR-0L-IISR-1L-II
SR-0L-HLSR-1L-HL
SR-0L-HISR-1L-HI
SR-0L-HHSR-1L-HH
tot
σ) /
pr
ed -
nob
s(n
2−02
Cut-and-count SRs
Multi-bin SRs
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Gtt/Gbb: Interpretations• Interpreted with the simplified model
using multi-bin SRs• New interpretation was done for gluino
branching ratio plane Gtt vs Gbb➡ Assuming three decay gluino’s modes:
Gtt, Gbb, Gtband Br(Gtt) + Br(Gbb) + Br(Gtb) = 100%
16
) [GeV]g~m(1200 1400 1600 1800 2000 2200 2400
) [G
eV]
10 χ∼m
(
0
200
400
600
800
1000
1200
1400
1600
1800
2000Expected limit in 2015Observed limit in 2015
)expσ1 ±Expected limit ()theory
SUSYσ1 ±Observed limit (
t + 2m
01χ∼ < m
g~m
)g~) >> m(q~, m(01χ∼+t t→ g~ production, g~g~
All limits at 95% CL
ATLAS-1=13 TeV, 36.1 fbs
Expected limit in 2015Observed limit in 2015
)expσ1 ±Expected limit ()theory
SUSYσ1 ±Observed limit (
Gtt
) [GeV]g~m(1200 1400 1600 1800 2000 2200
) [G
eV]
10 χ∼m
(
0
200
400
600
800
1000
1200
1400
1600
1800
2000Expected limit in 2015Observed limit in 2015
)expσ1 ±Expected limit ()theory
SUSYσ1 ±Observed limit (b + 2m
01χ
∼ < mg~m
)g~) >> m(q~, m(01χ∼+b b→ g~ production, g~g~
All limits at 95% CL
ATLAS-1=13 TeV, 36.1 fbs
Expected limit in 2015Observed limit in 2015
)expσ1 ±Expected limit ()theory
SUSYσ1 ±Observed limit (
Gbb
) [%]10χ∼ t t→ g~(B
0 10 20 30 40 50 60 70 80 90 100
) [%
]10 χ∼ b
b→ g~ (
B
0
10
20
30
40
50
60
70
80
90
100
ExpectedObserved
) = 1.8 TeVg~m() = 1.9 TeVg~m() = 2.0 TeVg~m(
) = 100%1-χ∼ b t→ g~(B) + 1
0χ∼ b b→ g~(B) + 1
0χ∼ t t→ g~(B
ATLAS-1=13 TeV, 36.1 fbs
) = 1 GeV10χ∼m(
Not allowed
LSP
mas
sLS
P m
ass
Gluino mass
Gluino mass
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Multi-jet channel
17
Searches for 3rd generations are in another talks
squarks/gluinos pair productions+
full hadronic decaysRPC0 lepton
Multi-jets
g̃
g̃
!̃02
!̃±1
p
p
t t
!̃01
Z/h
tb
!̃01
W
Many-step
pMSSM
2-6 jets
1 stepDirect
Gtt/Gbb
Gtt
Gbb
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Multi-jetMotivation
• Many-step cascade decay of SUSY particles can produce high Njet
• Unique sensitivity to some slices in pMSSM
The final state is characterised with• Moderate ET miss
• Njet ≥ 8 (7) with pT jet ≥ 50 (80) GeV
➡ ET miss Significance: ET
miss/√HT ≥ 5 GeV1/2
Final state with top quarks are considered in Jet mass stream• Sum of mass of re-clustered large-R jet (R=1.0): MJ
∑ ≡ ∑mjR=1.0
18
https://arxiv.org/abs/1708.02794
Heavy flavour stream• 21 SRs:
Njet ≥ 8, 9, 10, 11 (7, 8, 9) with pT
jet > 50 (80) GeVNb-jet ≥ 0, 1, 2✓Good sensitivity to signal
with high LSP mass regions
Jet mass stream• 6 SRs:
Njet ≥ 8, 9, 10 with pTjet > 50
MJ∑ > 340, 500 GeV
✓Good sensitivity to signal with high gluino mass regions
Multi-jets
g̃
g̃
!̃02
!̃±1
p
p
t t
!̃01
Z/h
tb
!̃01
W
Many-step
pMSSM
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Multi-jet: Background Estimation
19
QCD multi-jet data driven with “template” method Semi-leptonically decaying top quark pair MC normalised with top quark pair CR
W + jets W→lν MC normalised with W + jets enriched CRZ + jets Z→νν
MC normalised to the best available cross-section single top MC normalised to the best available cross-section
di-boson production
MC normalised to the best available cross-section
1/2
Num
ber o
f Eve
nts
/ 4 G
eV
10
210
310
410
510
610
710
810
910
10101− = 13 TeV, 36.1 fbs
VR-7j50-0b
ATLAS DataTotal backgroundMultijet
ql, ll→ tt + jetsν l→W
OtherpMSSM benchmark2-step benchmark
]1/2 [GeVTH / missTE
0 2 4 6 8 10 12 14 16 18
Data
/ Pr
ed.
00.5
11.5
2
1/2
Num
ber o
f Eve
nts
/ 4 G
eV
1
10
210
310
410
510
610
710
8101− = 13 TeV, 36.1 fbs
VR-7j50-MJ500
ATLAS DataTotal backgroundMultijet
ql, ll→ tt + jetsν l→W
OtherpMSSM benchmark2-step benchmark
]1/2 [GeVTH / missTE
0 2 4 6 8 10 12 14 16 18
Data
/ Pr
ed.
00.5
11.5
2
MJ-Template ≡ Data − Normalised BKG MC
in MetSig distribution at Njet=6
MJ-BKG@“k jets” ≡ MJ-Template × Ratio of Nevent
QCD in low MetSig (<1.5)
between Njet=6 and k
Heavy flavour VR Jet mass VR
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Multi-jet: Results
No excess was observed in any SRs
20
1/2
Num
ber o
f Eve
nts
/ 4 G
eV
2−10
1−10
1
10
210
310
410
510
610 1− = 13 TeV, 36.1 fbsSR-11j50-0b
ATLAS DataTotal backgroundMultijet
ql, ll→ tt + jetsν l→W
OtherpMSSM benchmark2-step benchmark
]1/2 [GeVTH / missTE
0 2 4 6 8 10 12 14 16 18
Data
/ Pr
ed.
00.5
11.5
2
1/2
Num
ber o
f Eve
nts
/ 4 G
eV
2−10
1−10
1
10
210
310
410
510
610
7101− = 13 TeV, 36.1 fbs
SR-10j50-MJ500
ATLAS DataTotal backgroundMultijet
ql, ll→ tt + jetsν l→W
OtherpMSSM benchmark2-step benchmark
]1/2 [GeVTH / missTE
0 2 4 6 8 10 12 14 16 18Da
ta /
Pred
.0
0.51
1.52
Even
ts
10
210
310
410Multijet + jetsi lAW Data
Other ql, llA tt Total Background
8j50
-0b
8j50
-1b
8j50
-2b
9j50
-0b
9j50
-1b
9j50
-2b
10j5
0-0b
10j5
0-1b
10j5
0-2b
11j5
0-0b
11j5
0-1b
11j5
0-2b
7j80
-0b
7j80
-1b
7j80
-2b
8j80
-0b
8j80
-1b
8j80
-2b
9j80
-0b
9j80
-1b
9j80
-2b
8j50
-MJ3
408j
50-M
J500
9j50
-MJ3
409j
50-M
J500
10j5
0-M
J340
10j5
0-M
J500
Dat
a / P
redi
ctio
n
0
0.5
1
1.5
2
ATLAS 1< = 13 TeV, 36.1 fbs
Heavy flavour Jet mass
Heavy flavour Jet mass
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
) [GeV]g~m(800 1000 1200 1400 1600 1800 2000 2200 2400
) [G
eV]
0 1r¾m
(
200
400
600
800
1000
1200
)01r¾
) = m
(
g~m(
)]/201
r¾)+m(±
1r¾)=[m(0
2r¾)]/2, m(0
1r¾)+m(g~)=[m(±
1r¾; m(0
1r¾ qqWZA g~ production, g~g~
ATLAS Combinedmiss
TMultijets + E
1<=13 TeV, 36.1 fbsAll limits 95% CL
)expm1 ±Expected ()theory
SUSYm1 ±Observed (1<ATLAS 13 TeV, 3.2 fb
Many-step
Multi-jet: Interpretations
Exclusion limit obtained with the SR with the best expected sensitivity at each mass point
21
) [GeV]g~m(1000 1200 1400 1600 1800 2000 2200 2400
) [G
eV]
± 1r¾m
(
200
300
400
500
600
700
8005 TeV5 )l~5 TeV, m( 5)q~=3 TeV, m(
2<0, Mµ=10, `=60 GeV, tan
1pMSSM: M
ATLAS Combinedmiss
TMultijets + E
1<=13 TeV, 36.1 fbsAll limits 95% CL
)expm1 ±Expected (
)theorySUSYm1 ±Observed (
1<ATLAS 13 TeV, 3.2 fb
pMSSM
LSP
mas
s
Char
gino
mas
s
Gluino massGluino mass
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Interpretations
22
Multi-jet 2-6 jets Gtt
) [GeV]g~m(500 1000 1500 2000 2500
) [G
eV]
0 1r¾m
(
200
400
600
800
1000
1200
1400
1600
1800ATLAS Preliminary
= 13 TeVs-136.1 fb
01
r¾Wq qAg~
December 2017
0-lepton expected0-lepton observed1-lepton expected1-lepton observedRun 1 expectedRun 1 observed
0-lepton: arXiv:1712.023321-lepton: arXiv:1708.08232Run 1: arXiv:1507.05525
))10
r¾)+m(g~(m(×21) =
1±
r¾m()
10
r¾)<
m(g~
m(
) [GeV]g~m(800 1000 1200 1400 1600 1800 2000 2200
) [G
eV]
0 1r¾m
(
200
400
600
800
1000
1200
1400
1600ATLAS Preliminary
-1 = 13 TeV, 36.1 fbs
01
r¾WZq qAg~
December 2017
7-11 jets expected* 7-11 jets observed*
1 lepton expected1 lepton observedSS leptons expectedSS leptons observedRun 1 expectedRun 1 observed
7-11 jets: arXiv:1708.02794*
1 lepton: arXiv:1708.08232SS leptons: arXiv:1706.03731Run 1: arXiv:1507.05525
))1
0r¾)+m(g~(m(×2
1) = 1±
r¾m( ))1
0r¾)+m(
1±
r¾(m(×21) =
2
0r¾m(
) [GeV]g~m(1000 1200 1400 1600 1800 2000 2200 2400 2600
) [G
eV]
0 1r¾m
(
200
400
600
800
1000
1200
1400
1600
1800
2000ATLAS Preliminary
-136.1 fb
= 13 TeVs, 01
r¾t tAg~
December 2017
3b jets expected* 3b jets observed*
SS leptons expectedSS leptons observedRun 1 expectedRun 1 observed 3b jets: 1711.01901*
SS leptons: 1706.03731Run 1: arXiv:1507.05525
t)+t1
0r¾
)<m(
g~m(
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
ConclusionThe proton-proton collision data in 2015 and 2016 collected by ATLAS, corresponding
integrated luminosity of 36.1 fb−1, are fully analysed and the results have been finalised.
Not only relying increased statistics, but also analyses have been improved their sensitivity.
Despite outstanding efforts, the evidence of squarks/gluinos has not appeared yet.
23
) [GeV]g~m(1000 1200 1400 1600 1800 2000
) [G
eV]
0 1r¾m
(
500
1000
1500
2000
2500ATLAS Preliminary -1 = 13 TeV, 36.1 fbs
December 2017
, 0-lepton, arXiv:1712.023320
1r¾q qAg~
, 0-lepton, arXiv:1712.023320
1r¾Wq qAg~
, 1-lepton, arXiv:1708.082320
1r¾Wq qAg~
7-11 jets, arXiv:1708.02794*, 0
1r¾WZq qAg~
, SS leptons, arXiv:1706.037310
1r¾WZq qAg~
, SS leptons, arXiv:1706.037310
1r¾t tAg~
3b jets, arXiv:1711.01901*, 0
1r¾t tAg~
3b jets, arXiv:1711.01901*, 0
1r¾b bAg~
Backup
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
2-6j: Results
25
Even
ts /
200
GeV
1
10
210
310
410 ATLAS -1=13 TeV, 36.1 fbs
Meff-2j-2100
Data 2015 and 2016
SM Total(+EW) & single toptt
Z+jets
Diboson
Multi-jet direct,q~q~
)=(600, 595)01
r¾
, q~m(
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C
00.5
11.5
2
Even
ts /
200
GeV
1
10
210
310
ATLAS -1=13 TeV, 36.1 fbs
Meff-2j-2800
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
direct,q~q~
)=(1500, 0)01
r¾
, q~m(
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C
00.5
11.5
2
Even
ts /
200
GeV
1
10
210
310
410 ATLAS
-1=13 TeV, 36.1 fbsMeff-4j-1000
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
direct,g~g~
)=(1300, 900)01
r¾
, g~m(
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C
00.5
11.5
2
Even
ts /
200
GeV
1
10
210
310
410 ATLAS
-1=13 TeV, 36.1 fbsMeff-4j-2200
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
direct,g~g~
)=(1800, 800)01
r¾
, g~m(
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C
00.5
11.5
2
Even
ts /
200
GeV
1
10
210
310 ATLAS
-1=13 TeV, 36.1 fbsMeff-6j-2600
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
onestep,g~g~
)=(1705, 865, 25)01
r¾
, ±1
r¾, g~m(
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C
00.5
11.5
2
Even
ts /
200
GeV
1
10
210
310 ATLAS
-1=13 TeV, 36.1 fbsMeff-2jB-2400
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
onestep,g~g~
)=(1600, 1590, 60)01
r¾
, ±1
r¾, g~m(
(incl.) [GeV]effm1000 1500 2000 2500 3000 3500 4000
Dat
a / M
C0
0.51
1.52
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
2-6j: Results
26
1000 1500 2000 2500 3000 [GeV]PP
T 2,1H
1<10
1
10
210
310
410
510
Even
ts /
125
GeV ATLAS
-1=13 TeV, 36.1 fbsRJR-S1a
Data 2015 and 2016SM Total
W+jets
(+EW) & single topttZ+jets
DibosonMulti-jet
direct,q~q~
)=(1100, 500)01
r¾
, q~m(
1000 1500 2000 2500 3000 [GeV]PP
T 2,1H0
0.51
1.52
Dat
a / M
C
1600180020002200240026002800300032003400 [GeV]PP
T 2,1H
1<10
1
10
210
310
410
510
610
Even
ts /
100
GeV ATLAS
-1=13 TeV, 36.1 fbsRJR-S3a
Data 2015 and 2016SM Total
W+jets
(+EW) & single topttZ+jets
DibosonMulti-jet
direct,q~q~
)=(1500, 0)01
r¾
, q~m(
1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 [GeV]PP
T 2,1H0
0.51
1.52
Dat
a / M
C
1000 1500 2000 2500 3000 [GeV]PP
T 4,1H
1<10
1
10
210
310
410
510
610
Even
ts /
125
GeV ATLAS
-1=13 TeV, 36.1 fbsRJR-G1a
Data 2015 and 2016SM Total
W+jets
(+EW) & single topttZ+jets
DibosonMulti-jet
direct,g~g~
)=(1500, 900)01
r¾
, g~m(
1000 1500 2000 2500 3000 [GeV]PP
T 4,1H0
0.51
1.52
Dat
a / M
C
1600180020002200240026002800300032003400 [GeV]PP
T 4,1H
1<10
1
10
210
310
410
510
610
710
Even
ts /
100
GeV ATLAS
-1=13 TeV, 36.1 fbsRJR-G3a
Data 2015 and 2016SM Total
W+jets
(+EW) & single topttZ+jets
DibosonMulti-jet
direct,g~g~
)=(2000, 0)01
r¾
, g~m(
1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 [GeV]PP
T 4,1H0
0.51
1.52
Dat
a / M
C
400 600 800 1000 1200 1400 1600 1800 2000 [GeV]CM
T Sp
1<10
1
10
210
310
410
510
610
Even
ts /
200
GeV ATLAS
-1=13 TeV, 36.1 fbsRJR-C2
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
direct,g~g~
)=(825, 775)01
r¾
, g~m(
400 600 800 1000 1200 1400 1600 1800 2000 [GeV]CM
T Sp
00.5
11.5
2
Dat
a / M
C
400 600 800 1000 1200 1400 1600 1800 2000 [GeV]CM
T Sp
1<10
1
10
210
310
410
510
Even
ts /
200
GeV ATLAS
-1=13 TeV, 36.1 fbsRJR-C4
Data 2015 and 2016SM TotalW+jets
(+EW) & single topttZ+jetsDibosonMulti-jet
direct,g~g~
)=(1000, 800)01
r¾
, g~m(
400 600 800 1000 1200 1400 1600 1800 2000 [GeV]CM
T Sp
00.5
11.5
2
Dat
a / M
C
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
Gtt/Gbb: Results
27
[GeV]missTE
200 300 400 500 600 700 800 900 1000
Even
ts /
100
GeV
20
40
60
80
100ATLAS
-1=13 TeV, 36.1 fbsGbb-VCCut-and-count analysis
DataTotal backgroundttSingle top + Xtt
Z+jetsW+jetsDibosonMultijet
) = 1200, 100010χ∼), m(g~Gbb: m(
) = 1400, 120010χ∼), m(g~Gbb: m(
[GeV]missTE
200 300 400 500 600 700 800 900 1000
Even
ts /
100
GeV
0.51
1.52
2.53
3.54
4.5 ATLAS-1=13 TeV, 36.1 fbs
1L-IIMulti-bin analysis
DataTotal backgroundtt
Single top + Xtt
Z+jetsW+jetsDiboson
) = 1900, 110χ∼), m(g~Gtt: m(
) = 1900, 60010χ∼), m(g~Gtt: m(
[GeV]missTE
200 300 400 500 600 700 800 900 1000Ev
ents
/ 10
0 G
eV0.5
1
1.5
2
2.5
3
3.5
4ATLAS
-1=13 TeV, 36.1 fbsGtt-1L-BCut-and-count analysis
DataTotal backgroundtt
Single top + Xtt
Z+jetsW+jetsDiboson
) = 1900, 110χ∼), m(g~Gtt: m(
) = 1900, 60010χ∼), m(g~Gtt: m(
[GeV]missTE
200 300 400 500 600 700 800 900 1000
Even
ts /
100
GeV
123456789
ATLAS-1=13 TeV, 36.1 fbs
0L-HIMulti-bin analysis
DataTotal backgroundtt
Single top + Xtt
Z+jetsW+jetsDibosonMultijets
) = 1900, 110χ∼), m(g~Gtt: m(
) = 1900, 60010χ∼), m(g~Gtt: m(
[GeV]missTE
200 300 400 500 600 700 800 900 1000Ev
ents
/ 10
0 G
eV
2
4
6
8
10 ATLAS-1=13 TeV, 36.1 fbs
0L-HHMulti-bin analysis
DataTotal backgroundtt
Single top + Xtt
Z+jetsW+jetsDibosonMultijets
) = 1900, 110χ∼), m(g~Gtt: m(
) = 1900, 60010χ∼), m(g~Gtt: m(
Searches for squarks and gluinos in all-hadronic final states with ATLASKoichi NAGAI
) [GeV]g~m(900 1000 1100 1200 1300 1400 1500 1600 1700
) [G
eV]
0 1r¾m
(
0
100
200
300
400
500
600
700
800
900
1000
) + 2m(t)0
1r¾
) = m(g~m(
)g~) >> m(q~, m(01
r¾+t tAg~ production, g~g~
ATLAS Combinedmiss
TMultijets + E
1<=13 TeV, 36.1 fbsAll limits 95% CL
)expm1 ±Expected (
)theorySUSYm1 ±Observed (
Gtt
Multi-jet: Interpretations
Exclusion limit obtained with the SR with the best expected sensitivity at each mass point
28
) [GeV]g~m(400 600 800 1000 1200 1400 1600
) [G
eV]
1t~m
(
400
500
600
700
800
900
1000
1100
1200
) + m
(t)
1t~) =
m(
g~m(
tbs (RPV)At 1t~ Ag~ production, g~g~
ATLAS Combinedmiss
TMultijets + E
1<=13 TeV, 36.1 fbsAll limits 95% CL
)expm1 ±Expected (
)theorySUSYm1 ±Observed (
RPV
LSP
mas
s
stop
mas
s
Gluino massGluino mass
Recommended