Higgs boson searches at ATLAS - indico.bnl.gov€¦ · Tae Min Hong 2 Outline • ATLAS detector...
Transcript of Higgs boson searches at ATLAS - indico.bnl.gov€¦ · Tae Min Hong 2 Outline • ATLAS detector...
Univ. of Pennsylvania
Tae Min Hong
ATLAS Experiment
Higgs boson searches at ATLASRecent updates
1
Brookhaven Forum 2011First Glimpse of the Tera Scale
http://www.bnl.gov/bf2011
Tae Min Hong
2
Outline
• ATLAS detector
• Selected Higgs searches
‣ H → ZZ(*) → ℓℓ+ℓℓ
‣ H → ZZ(*) → ℓℓ+νν
‣ H → WW(*) → ℓν+ℓν
‣ H → γγ
• MH exclusion limits
• Future outlook
• References, Thanks
“Higgs” is a BIG topic.I’ll focus on H → WW → ℓν+ℓν, which I work on, and 3 other SM decay modes with the best sensitivity (currently) for some mass ranges. Many decay modes that are not discussed here are also important for understanding the Higgs sector!
MH [GeV]
H→ZZ→4ℓ (Z→ℓν)2
300200
γγ
100
This is just a cartoon. In reality, the ranges overlap everywhere & all modes contribute.
(W→ℓν)2
|η| < 3.2 Pb-LAr accordion
Tae Min HongATLAS detector
3
|η| < 2.5
σ = 10%√E ⊕ 0.7%E
σ = 0.05% PT (GeV) ⊕ 1%PT
|η| < 2.7
= 10% at 1 TeVσ = 2% at 50 GeVPT
Air-core toroids + Gas-based chambers
|η| < 1.7 Fe/scintillator1.3 < |η| < 4.9 Cu/W-LAr
σ = 50% ⊕ 3%Ejet √E
2 Tesla field
Day in 201101/03 27/04 24/06 21/08 18/10
Peak
Ave
rage
Inte
ract
ions
/BX
0
5
10
15
20
25
30
35
40 = 7 TeVs ATLAS OnlineLHC Delivered
May JuneJuly Aug OctApril
Mar SepDay in 2011
01/03 27/04 24/06 21/08 18/10
]-1To
tal I
nteg
rate
d Lu
min
osity
[fb
0
1
2
3
4
5
6
7 = 7 TeVs ATLAS Online Luminosity
LHC Delivered
ATLAS Recorded
-1Total Delivered: 5.21 fb-1Total Recorded: 4.88 fb
Day in 201101/03 01/0403/05 03/06 05/0705/08 06/0907/10 08/11
]-1 s-2 cm33
Peak
Lumino
sity pe
r Fill [
10
00.5
11.5
22.5
33.5
44.5 = 7 TeVs ATLAS Online Luminosity
LHC Stable Beams-1 s-2 cm33 10!Peak Lumi: 3.59
~100 pb-1 / day since Sept. Pile-up 50 ns bunch trains
half a fb field17 mi around
Tae Min HongATLAS data taking in 2011 at 7 TeV
4
May JuneJuly Aug OctApril
Mar Sep
95% efficiency
3.3e33 peak L
4.9 fb-1 on tape
Newer
data
Presen
ted to
day
50 ns gap
distance
Day in 201101/03 01/0403/05 03/06 05/0705/08 06/0907/10 08/11
]-1 s
-2 c
m33
Peak
Lum
inos
ity p
er F
ill [1
0
00.5
11.5
22.5
33.5
44.5 = 7 TeVs ATLAS Online Luminosity
LHC Stable Beams-1 s-2 cm33 10!Peak Lumi: 3.59
Day in 201101/03 01/0403/05 03/06 05/0705/08 06/0907/10 08/11
]-1 s
-2 c
m33
Peak
Lum
inos
ity p
er F
ill [1
0
00.5
11.5
22.5
33.5
44.5 = 7 TeVs ATLAS Online Luminosity
LHC Stable Beams-1 s-2 cm33 10!Peak Lumi: 3.59
Day in 201101/03 27/04 24/06 21/08 18/10
Peak
Ave
rage
Inte
ract
ions
/BX
0
5
10
15
20
25
30
35
40 = 7 TeVs ATLAS OnlineLHC Delivered
~6
~12
0 0.5 1 1.5 2 2.5
2.28
1.03
1.06
1.04
1.70
1.04
1.04
2.28
1.04
1.06
1.08
fb-1
Tae Min HongATLAS Higgs recent results
5
Decay Reference
H → γγ arXiv:1108.5895
H → ττ ATLAS-CONF-2011-133
H → bb ATLAS-CONF-2011-103
H → ZZ(*) → ℓℓ+ℓℓ arXiv:1109.5945
H → ZZ(*) → ℓℓ+qq arXiv:1108.5064
H → ZZ(*) → ℓℓ+νν arXiv:1109.3357
H → WW(*) → ℓν+ℓν ATLAS-CONF-2011-134
H → WW(*) → ℓν+qq arXiv:1109.3615
MSSM H → ττ ATLAS-CONF-2011-132
MSSM H+ ATLAS-CONF-2011-138
SM Higgs combination ATLAS-CONF-2011-135
We have ~5 fb-1 on tape; see p.20.
1.03
1.96
[GeV] HM100 200 300 400 500 1000
H+X
) [pb
]
(pp
-210
-110
1
10= 7 TeVs
LHC
HIG
GS
XS W
G 2
010
H (NNLO+NNLL QCD + NLO EW)
pp
qqH (NNLO QCD + NLO EW)
pp
WH (NNLO QCD + NLO EW)
pp ZH (NNLO QCD +NLO EW)
pp
ttH (NLO QCD)
pp
Tae Min Hong
6
Higgs production, decay
Higgs productionggF is dominant (10× Tevatron)
g
gt H
H
q
qWW
H
W,ZW,Zq
q
g
g
t
H
t
tt
Gluon-gluon fusion (ggF)Vector-boson fusion (VBF)
Associated prod’n
MH=120 MH=150 MH=300
43 16 0.04
127 390 89
1.5 4.6 3.8
Decay
H→γγH→WW(*)→ℓν+ℓνH→ZZ(*)→ℓℓ+ℓℓ
[GeV]HM100 200 300 400 500
BR
[pb]
!
-410
-310
-210
-110
1
10
LHC
HIG
GS
XS W
G 2
011
SM = 7TeVs
"l = e, ,",e =
q = udscbbb# lWH
bb-l+ lZH
-+ VBF H
-+ H
qq# lWW
-l+ lWW
qq-l+ lZZ -l+ lZZ
-l+l-l+ lZZ
ZZ turn-on
MH [GeV] MH [GeV]
SM Higgs at 7 TeV• ℓ = e or µ• ν = all 3 flavors• q = exclude top
Low Medium High
Prod’n × decay3 mass regions
Table of events expected per fb-1
Does not include acceptance
ggF
× B
R [p
b] WW turn-on
Tae Min HongH → ZZ(*) → ℓℓ+ℓℓ
7
μ
μ
e
e
85.5 GeV
85.9 GeV
μ
μ
e
e
M4ℓ = 209.7
• H → ZZ(*) → ℓℓ+ℓℓ : full reco = mass peak
• Clean! M(ℓ+ℓ−) ~ MZ
• Sensitivity ~ 200<MH<300100 200 300
MHH→ZZ→4ℓ
[GeV]4lm100 200 300 400 500 600
Even
ts/1
0 G
eV
012
34567
89
-1 Ldt = 1.96-2.28 fb = 7 TeVs
4l(*)ZZH
DATABackground
=150 GeV)H
Signal (m=220 GeV)
HSignal (m
2!=480 GeV) H
Signal (m
ATLAS
[GeV]Hm200 300 400 500 600
SM/
95%
CL
limit
on
1
10
210sObserved CL
sExpected CL 1 ! 2 !
ATLAS 4l(*) ZZH
-1Ldt = 1.96-2.28 fb=7 TeVs
sObserved CLsExpected CL
1 ! 2 !
sObserved CLsExpected CL
1 ! 2 !
Tae Min HongH → ZZ(*) → ℓℓ+ℓℓ : analysis
8
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCLCL S
Lim
its o
n observed expected
±1σ
±2σ
MH=150
MH=220Bkgs.
2xMH=480
Excluded Higgs masses• 95% confidence level limits using CLS
• Expected : 194 GeV is closest at 1.01×SM
• Observed : 191-197, 199-200, 214-224
Even
ts /
10 G
eV
1
Data
3
24
Expected SMExpected SMExpected SM
Total SM ZZ
Zbb, ttbar
3.0 2.4 0.6
21 21 0.3
Expected for MHExpected for MHExpected for MHExpected for MHExpected for MH
130 150 200 300 400
1.0 2.3 N/AN/AN/A
N/AN/A 5.9 3.5 2.6
MH
<180
≥180
[GeV]Hm200 300 400 500 600
SM/
95%
CL
limit
on
1
10
210sObserved CL
sExpected CL 1 ! 2 !
ATLAS 4l(*) ZZH
-1Ldt = 1.96-2.28 fb=7 TeVs
sObserved CLsExpected CL
1 ! 2 !
sObserved CLsExpected CL
1 ! 2 !
[GeV]Hm200 300 400 500 600
SM/
95%
CL
limit
on
1
10
210sObserved CL
sExpected CL 1 ! 2 !
ATLAS 4l(*) ZZH
-1Ldt = 1.96-2.28 fb=7 TeVs
sObserved CLsExpected CL
1 ! 2 !
sObserved CLsExpected CL
1 ! 2 !
Want |M(ℓ+ℓ−)-MZ|<15 with another ℓ′+ℓ′−
• Lepton selection : Two PT >20, All PT >7
• Split data at MH=180 where ZZ turns-on
• Backgrounds
‣ SM ZZ(*)→ℓℓ+ℓℓ : Use MC ; Err~15%
‣ Z+bb, b→ℓ fake : Use data ; Err~20-40%
‣ ttbar→(Wb)2, W→ℓν : Use MC ; Err~10%
• H → ZZ(*) → ℓℓ+νν : partial reco = count
• M(ℓ+ℓ−)~MZ with ETmiss for νν
• Sensitivity ~ MH>300
eilam gross, WIS, LHC2TSP, August 2011
Heavier Higgs: H->llννSignature: two high pT opposite charged isolated leptons with high MET
38
pT µ = 50,126 GeVmµµ = 94 GeV
ETmiss = 161GeV
Saturday, September 3, 2011
μ
μ
Tae Min HongH → ZZ(*) → ℓℓ+νν
9
eilam gross, WIS, LHC2TSP, August 2011
Heavier Higgs: H->llννSignature: two high pT opposite charged isolated leptons with high MET
38
pT µ = 50,126 GeVmµµ = 94 GeV
ETmiss = 161GeV
Saturday, September 3, 2011
Eve
nts
/ 5
Ge
V
110
210
310
410
510
610
Eve
nts
/ 5
Ge
V
110
210
310
410
510
610 -1 L dt = 1.04 fbData Total Background
TopZZ,WZ,WWZ
Other Backgrounds = 400 GeV)
HSignal (m
ATLAS = 7 TeVs ll ZZ H
[GeV]missTE
0 50 100 150 200 250 300Data
/ M
C
0.81
1.2
[GeV]missTE
0 50 100 150 200 250 300Data
/ M
C
0.81
1.2
Even
ts /
5 G
eV
110
210
310
410
510
610
Even
ts /
5 G
eV
110
210
310
410
510
610 -1 L dt = 1.04 fbData Total Background
TopZZ,WZ,WWZ
Other Backgrounds = 400 GeV)
HSignal (m
ATLAS = 7 TeVs ll ZZ H
[GeV]missTE
0 50 100 150 200 250 300Data
/ M
C
0.81
1.2
[GeV]missTE
0 50 100 150 200 250 300Data
/ M
C
0.81
1.2
ETmiss [GeV]
Even
ts /
5 G
eV
10k
100
1 Other bkgs.
DibosonZTop
MH = 400
[GeV]Hm200 250 300 350 400 450 500 550 600
SM/
95%
CL
limit
on
0
2
4
6
8
10
12
14ObservedExpected 1!
2!
ATLAS
=7TeVs, -1Ldt=1.04 fb
llZZH
[GeV]Hm200 250 300 350 400 450 500 550 600
SM/
95%
CL
limit
on
0
2
4
6
8
10
12
14ObservedExpected 1!
2!
ATLAS
=7TeVs, -1Ldt=1.04 fb
llZZH
PTlead = 126PTsublead = 50
Mℓℓ = 94ETmiss = 161
eilam gross, WIS, LHC2TSP, August 2011
Heavier Higgs: H->llννSignature: two high pT opposite charged isolated leptons with high MET
38
pT µ = 50,126 GeVmµµ = 94 GeV
ETmiss = 161GeV
Saturday, September 3, 2011
μ
μ
100MH H→ZZ→4ℓ (Z→ℓν)2
300200
ETmiss
Want M(ℓ+ℓ−)=MZ with ETmiss
• Lepton selection : Leading PT >25 GeV
• Backgrounds : top, SM ZZ, WZ, WW
• Split data at MH=280 : ZZ become boosted
Err ~15%, σW, σtop biggest 3% ~50%reco.
Tae Min HongH → ZZ(*) → ℓℓ+νν : analysis, result
10
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCLCL S
Lim
its o
n
[GeV]Hm200 250 300 350 400 450 500 550 600
SM
/ 9
5%
CL lim
it o
n
0
2
4
6
8
10
12
14ObservedExpected 1!
2!
ATLAS
=7TeVs, -1Ldt=1.04 fb
llZZH
[GeV]Hm200 250 300 350 400 450 500 550 600
SM/
95%
CL
limit
on
0
2
4
6
8
10
12
14ObservedExpected 1!
2!
ATLAS
=7TeVs, -1Ldt=1.04 fb
llZZH8
6
10
4
MH [GeV]
2
[GeV]Hm200 250 300 350 400 450 500 550 600
SM/
95%
CL
limit
on
0
2
4
6
8
10
12
14ObservedExpected 1!
2!
ATLAS
=7TeVs, -1Ldt=1.04 fb
llZZH
[GeV]Hm200 250 300 350 400 450 500 550 600
SM/
95%
CL
limit
on
0
2
4
6
8
10
12
14ObservedExpected 1!
2!
ATLAS
=7TeVs, -1Ldt=1.04 fb
llZZH observed
expected
±1σ
±2σ
[GeV]Tm200 300 400 500 600 700
Even
ts /
50 G
eV
05
10152025303540
[GeV]Tm200 300 400 500 600 700
Even
ts /
50 G
eV
05
10152025303540
-1 L dt = 1.04 fbdata
Total BackgroundTopZZ,WZ,WWZ,W
= 380 GeV)H
Signal (m
ATLAS = 7 TeVs
ll ZZ H
MT [GeV]
Excluded Higgs masses• Use bins MT2 = (ETℓℓ + ETmiss)2 - (PTℓℓ+PTmiss)2
• Expected : 380 GeV is closest at 1.1×SM• Observed : 340 < MH < 450 GeV
Data
85
47
Expected SMExpected SMExpected SMExpected SMExpected SM
Total Z+j W+j top VV
105 19 8.5 30 47
55 6.0 3.1 15 31
Expected for MHExpected for MHExpected for MHExpected for MHExpected for MH
200 300 400 500 600
5.0 N/AN/AN/AN/A
N/A 10 10 4.5 1.8
MH
<280
≥280
Nearest jet same ϕ-hemi.Away ℓ
ETmiss
Δϕℓ,jet reject < 0.3
• Reject fake ETmiss from jet mismeas’t with
Tae Min HongH → WW(*) → ℓν+ℓν
11
ETmiss
μ
e
• H → WW(*) → ℓν+ℓν : partial reco = count
• Similar to ZZ(*) → ℓℓ+νν, but M(ℓℓ)≠MZ
• Sensitivity ~ 125<MH<200100
(Z4ℓ)2300200
MH (Wℓν)2 (Zℓν)2
Entr
ies / 0
.13
20
40
60
80
100 Data stat) SM (sys WW WZ/ZZ/W
t t Single Top Z+jets W+jets (data driven)
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
+ 0 jetsllWWH
(ll) [rad]0 0.5 1 1.5 2 2.5 3
Data
/ M
C
0.51
1.52 ππ/20 |ΔΦℓℓ| [rad]
Even
ts in
10
bins
20
40
60
WW
W+jetsZ+jets
top
MH=150
Err. ~50-100% in this region
Entri
es /
4 G
eV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Dat
a / M
C
0.51
1.520
NJet=0 after pre-sel.
μ
eETmiss
ΔΦℓℓ
Want M(ℓ+ℓ−)≠MZ with ETmiss
• Leading lept. PT : e, μ=25
• Sublead. lept. PT : e=20, μ=15
• Backgrounds : Next slide
• ET,relmiss cut : ee, μμ=40, eμ=25
Tae Min HongH → WW(*) → ℓν+ℓν : pre-selection
12
• Definition of ET,relmiss
If such ℓ or jet in same ϕ-hemisph.,
Otherwise, ET,relmiss = ETmiss
ℓ or jet
Away ℓ
ETmiss
ET,relmiss reject if < 40, 25Δϕeeμμ
eμ
Data
1E+06
1E+05
4051
Expected SMExpected SMExpected SMExpected SMExpected SMExpected SM
Total SM WW top W+j Z+j VZ
1M 1.4k 7k 1M 1k
.1M 1.2k 6k .1M 100
4k 660 3k 300 30
Selection
Mℓℓ>15, Meµ>10
|Mℓℓ or eµ−MZ|>15
ET,relmiss
Even
ts /
4 G
eVE
ntr
ies /
4 G
eV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
!!WWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Data
/ M
C
0.51
1.52
Z+jets
W+jets
WW
1-top
diboson ttbar10
1000
10k
0.1
MH=150
Entr
ies / 4
GeV
-210
-1101
10
210
310
410
510 Data stat) SM (sys WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
!eWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Da
ta /
MC
0.51
1.52
Entri
es /
4 G
eV-210
-1101
10
210
310
410
510 Data stat) SM (sys WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
!eWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Dat
a / M
C
0.51
1.52
ET,relmiss [GeV]
diboson
ttbarWW
1-top
Zj
Wj
10
100
0.1
1
MH=150E
ntr
ies / 4
GeV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Da
ta /
MC
0.51
1.52
Z+jetsW+jets
WW
1-top
diboson ttbar10
1000
100k
0.1
MH=150
Entri
es /
4 G
eV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Dat
a / M
C
0.51
1.52
eμ channel
μμ channel
ee channel
data
-der
ived
Tae Min HongH → WW(*) → ℓν+ℓν : backgrounds, final selection
13
BackgroundsMostly data-derived quantitites
• SM WW(*) : Mℓℓ data CR →SR w/MC ; Err~10%
• top : b-jet data CR →SR w/MC ; Err~10%
• W+jet : di-jet data CR →SR w/data ; Err~30%
• Others : MC predictions, small
Higgs SR SM WW CR
Even
ts /
5 G
eV
1
100
10
En
trie
s /
5 G
eV
-210
-110
1
10
210
310
410
510 Data stat) SM (sys WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
!eWWH
[GeV]!eM0 50 100 150 200 250
Da
ta /
MC
0.51
1.52
Entri
es /
5 G
eV
-210
-110
1
10
210
310
410
510 Data stat) SM (sys WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
!eWWH
[GeV]!eM0 50 100 150 200 250
Dat
a / M
C
0.51
1.52
Meμpre-ET,relmiss
Entri
es /
4 G
eV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Dat
a / M
C
0.51
1.52
MH=150
1-top
WW
Z+jets
W+jets
ttbar
diboson
Final selection• Split data into Njets = 0, 1 (reject b-jets)
• “Topological” cuts exploit spin-0 decay
‣ small ΔΦℓℓ, large PTℓℓ, low Mℓℓ
‣ MT (defined on p.10)E
ntrie
s
200400600800
100012001400160018002000 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets (data driven)
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
llWWH
jetsN0 2 4 6 8 10
Dat
a / M
C
0.51
1.52
ttbarWW
1tNJetspost-ET,relmiss0 1 2 3 4 5 60
400
800
1.2k
MH=150
Wj
ZjEv
ents
Entri
es /
4 G
eV-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Dat
a / M
C
0.51
1.52
Data
70
23
Expected SMExpected SMExpected SMExpected SMExpected SMExpected SM
SM WW top W+j Z+j VV Total
43±6 2.2±1.4 4.7±1.5 1.8±3.6 0.7±3.6 53±9
10±1.5 6.9±1.9 0.7±0.4 1.2±1.1 0.6±0.2 23±4
Selection
Njets=0
Njets=1
Higgs
MH = 150
34±7
12±2
Tae Min Hong
14
H → WW(*) → ℓν+ℓν : results
Entr
ies / 1
0 G
eV
51015202530354045 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets (data driven)
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
+ 0 jetsllWWH
[GeV]TM60 80 100 120 140 160 180 200 220 240
Da
ta /
MC
0.51
1.52
Entri
es /
10 G
eV
51015202530354045 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets (data driven)
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
+ 0 jetsllWWH
[GeV]TM60 80 100 120 140 160 180 200 220 240
Dat
a / M
C
0.51
1.52
Even
ts /
10 G
eV
0
10
20
15
5
Excluded Higgs masses• Expected : 135 < MH < 196 GeV
• Observed : 154 < MH < 186 GeV
• 2 sigma excess below ~160 GeV
1-top
WW
Z+jets
W+jets
ttbar
diboson
MT [GeV]
Entr
ies / 1
0 G
eV
2468
1012141618 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets (data driven)
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
+ 1 jetllWWH
[GeV]TM60 80 100 120 140 160 180 200 220 240
Da
ta /
MC
0.51
1.52
Entri
es /
10 G
eV
2468
1012141618 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets (data driven)
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
+ 1 jetllWWH
[GeV]TM60 80 100 120 140 160 180 200 220 240
Dat
a / M
C
0.51
1.524
6
2
8 MH=150
MH=150
MT, Transverse mass (last cut)• Njets = 0
Entri
es /
4 G
eV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200
Dat
a / M
C
0.51
1.52
[GeV]Hm120 140 160 180 200 220 240 260 280 300
SM
/95%
CL L
imit o
n
-110
1
10
210ObservedExpected 1 ! 2 !
ATLAS Preliminary
-1 Ldt = 1.7 fb = 7 TeVs
ll(*)WWHCLs Limits
[GeV]Hm120 140 160 180 200 220 240 260 280 300
SM/
95%
CL
Lim
it on
-110
1
10
210ObservedExpected 1 ! 2 !
ATLAS Preliminary
-1 Ldt = 1.7 fb = 7 TeVs
ll(*)WWHCLs Limits
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
CL S
on
1
10
Entri
es /
4 G
eV
-210-1101
10210310410510610710810910 Data stat) SM (sys
WW WZ/ZZ/W
t t Single Top Z+jets W+jets
H [150 GeV]
ATLAS Preliminary-1 L dt = 1.70 fb = 7 TeV, s
eeWWH
[GeV]T,relmissE
0 20 40 60 80 100 120 140 160 180 200D
ata
/ MC
0.51
1.52
observed expected
±1σ
±2σ
[GeV]Hm120 140 160 180 200 220 240 260 280 300
Stat
istica
l sig
nific
ance
0
2
4
6
8
10 ObservedExpected 1 ! 2 !
-1 Ldt = 1.7 fb = 7 TeVs
ATLAS Preliminary ll(*)WWH
[GeV]Hm120 140 160 180 200 220 240 260 280 300
Stat
istica
l sig
nific
ance
0
2
4
6
8
10 ObservedExpected 1 ! 2 !
-1 Ldt = 1.7 fb = 7 TeVs
ATLAS Preliminary ll(*)WWHSt
atis
tical
Sig
nific
ance
3
5
evid
ence
expected observed
MH [GeV]
25
• Njets = 1
• !"#$%&'()*"%&'+,-./#"%0-,1%-,-*$&'&2%
• 345.5,%'1",678-65,%9-&"1%95.4%5,%*-."#-*%-,1%*5,+'./1',-*%&"+(",.-65,%5:%.4"%;*"8.#5(-+,"68%8-*5#'("."#%
• <=5%4'+4>?/-*'.$%'&5*-."1%4'+4>)<%)45.5,&%– %)<@%A%BC%D"!E%%%)<F%A%FG%D"!%– %%HI@FH%J%@KLM%-,1%@KGF%J%HI@FH%JFKLM%%
N!OO%P%"Q",.%&"*"865,%
)#"&45="#%
R-()*',+%L%
R-()*',+%F%
R-()*',+%@%
!"#$%&'()**'+,-,'
S"."Q'%TK%T&&-(-+-,%>%%URVWNX%YX<3><#'"&."Z%R")."(9"#%FC@@%
!"#!$%
@C%
• !"#$%&'()*"%&'+,-./#"%0-,1%-,-*$&'&2%
• 345.5,%'1",678-65,%9-&"1%95.4%5,%*-."#-*%-,1%*5,+'./1',-*%&"+(",.-65,%5:%.4"%;*"8.#5(-+,"68%8-*5#'("."#%
• <=5%4'+4>?/-*'.$%'&5*-."1%4'+4>)<%)45.5,&%– %)<@%A%BC%D"!E%%%)<F%A%FG%D"!%– %%HI@FH%J%@KLM%-,1%@KGF%J%HI@FH%JFKLM%%
N!OO%P%"Q",.%&"*"865,%
)#"&45="#%
R-()*',+%L%
R-()*',+%F%
R-()*',+%@%
!"#$%&'()**'+,-,'
S"."Q'%TK%T&&-(-+-,%>%%URVWNX%YX<3><#'"&."Z%R")."(9"#%FC@@%
!"#!$%
@C%
Want two isolated photons• Photon selection : PT > 40, 25
• Photon identif’n : Use lat.+long. segmentation
• Backgrounds : See top-right
‣ Data-derived e → γ
‣ Relaxed isolation, identification
• Split data into detector region, γ→ee conversion
Sampling 3
Sampling 2
Sampling 1Pre-shower
Data from Spring 2011
Tae Min HongH → γγ
15
0
5
10
15
20
110 120 130 140 150
1.1
1.7
2.32.62.6
2.1
3.4
4.24.74.6
0.8
1.3
1.74.2
2.0
1.01.5
2.1
3.4
2.3
2.74.25.62.1
5.6H
→γγ
aft
er c
uts
/ 1.0
8 fb
-1
M_H [ GeV]
converted restconv. transitionconv. centralunconv. restunconv. central
W γ
γH
q
γ
γ
q
γ
gq
q
many diagrams
+ ...
+ ...
0.04 pb
30 pb
105 pb
108 pb
H → γγ
γγ
γ+jet
jet+jet
Feynman diag. & cross-sections
0.025×0.025
0.003 to 0.006 (4mm)
Beam pipe
MH H→ZZ→4ℓ ZZ→ℓν300200
γγ100
3-5
4-15
17
X0
2.5-6
(Wℓν)2
• H → γγ : full reco = mass peak
• Sensitivity ~ MH<125
[GeV]m100 110 120 130 140 150 160
Eve
nts
/ 2.0
GeV
0
50
100
150
200
250
300
350
400
450
ATLAS
Data 2011Background exp. fit
= 120 GeV, 5xSMH
Bkg + MC signal m
Inclusive diphoton sample
-1 Ldt = 1.08 fb = 7 TeV, s
100
300
200
0
Even
ts /
2 G
eV
[GeV]m100 110 120 130 140 150 160
Even
ts /
2.0
GeV
0
50
100
150
200
250
300
350
400
450
ATLAS
Data 2011Background exp. fit
= 120 GeV, 5xSMH
Bkg + MC signal m
Inclusive diphoton sample
-1 Ldt = 1.08 fb = 7 TeV, s
[GeV]m100 110 120 130 140 150 160
Eve
nts
/ 2.0
GeV
0
50
100
150
200
250
300
350
400
450
ATLAS
Data 2011Background exp. fit
= 120 GeV, 5xSMH
Bkg + MC signal m
Inclusive diphoton sample
-1 Ldt = 1.08 fb = 7 TeV, s
[GeV]m
100 110 120 130 140 150 160
]-1
[GeV
dN/d
m
0
50
100
150
200Data 2011
j + jjjDYStatistical errorTotal error
ATLAS-1 Ldt = 1.08 fb = 7 TeV, s
72%
We’re closing-in on the LEP limit!
Tae Min HongH → γγ : analysis, results
16
Excluded Higgs masses• Fit with exponential + signal shape.
• No range is excluded yet, but 120<MH<130 GeV is getting close.
Mγγ [GeV]
[GeV]Hm110 115 120 125 130 135 140 145 150
)/S
M @
95%
CL
BR
(H!
0
2
4
6
8
10
12
14
16 limitsObserved CL limitsExpected CL
1" 2"
ATLAS H = 7 TeVsData 2011, -1Ldt = 1.08 fb
[GeV]Hm110 115 120 125 130 135 140 145 150
)/SM
@ 9
5% C
LBR
(H!
0
2
4
6
8
10
12
14
16 limitsObserved CL limitsExpected CL
1" 2"
ATLAS H = 7 TeVsData 2011, -1Ldt = 1.08 fb
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCLCL S
Lim
its o
n
2
4
10
6
8
MH [GeV] [GeV]m100 110 120 130 140 150 160
Even
ts /
2.0
GeV
0
50
100
150
200
250
300
350
400
450
ATLAS
Data 2011Background exp. fit
= 120 GeV, 5xSMH
Bkg + MC signal m
Inclusive diphoton sample
-1 Ldt = 1.08 fb = 7 TeV, s
[GeV]m100 110 120 130 140 150 160
Eve
nts
/ 2.0
GeV
0
50
100
150
200
250
300
350
400
450
ATLAS
Data 2011Background exp. fit
= 120 GeV, 5xSMH
Bkg + MC signal m
Inclusive diphoton sample
-1 Ldt = 1.08 fb = 7 TeV, s
expected
observed
±1σ
±2σ
Even
ts /
5 G
eV
Mass resolution = 1.4 - 2.1 GeV
5x MH=120 GeV
[GeV]m
100 110 120 130 140 150 160
]-1
[GeV
dN/d
m
0
50
100
150
200Data 2011
j + jjjDYStatistical errorTotal error
ATLAS-1 Ldt = 1.08 fb = 7 TeV, s
72%
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
CL S
Lim
its o
n
Exclusion limits of various results: solid is observed, dotted is expectedFor results were not discussed in prev. slides see p.3.
[GeV]Hm100 200 300 400 500 600
SM
/95%
CL lim
it o
n
1
10
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
Exp. Obs. Exp. Obs.
=7 TeVs, -1 L dt ~ 1.0-2.3 fb CLs limitsATLAS Preliminary
[GeV]Hm100 200 300 400 500 600
SM
/95%
CL lim
it o
n
1
10
1
10
Tae Min HongMH exclusion limit : individual
17
H→ττ
H→ZZ(*)→ℓℓνν
H→γγ
H→WW(*)→ℓνℓν
H→ZZ(*)→ℓℓqq
H→ZZ(*)→ℓℓℓℓ
VH, H→bb
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
Low Medium High
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
Exp. Obs. Exp. Obs.
=7 TeVs, -1 L dt ~ 1.0-2.3 fb CLs limitsATLAS Preliminary
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
Exp. Obs. Exp. Obs.
=7 TeVs, -1 L dt ~ 1.0-2.3 fb CLs limitsATLAS Preliminary
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
MH [GeV]
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
Exp. Obs. Exp. Obs.
=7 TeVs, -1 L dt ~ 1.0-2.3 fb CLs limitsATLAS Preliminary
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
Exp. Obs. Exp. Obs.
=7 TeVs, -1 L dt ~ 1.0-2.3 fb CLs limitsATLAS Preliminary
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
limit
on
1
10
Combined exclusion limits: solid is observed, dotted is expected
[GeV]Hm100 200 300 400 500 600
SM
/9
5%
CL L
imit o
n
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
Tae Min HongMH exclusion limit : combined
18
1
10
Observed• 146 < MH < 466
with gaps at• 232 < MH < 256• 282 < MH < 296
Expected exclusion• 131 < MH < 450
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
CL S
Lim
its o
n
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
[GeV]Hm100 200 300 400 500 600
SM/
95%
CL
Lim
it on
-110
1
10
ObservedExpected
ObservedExpected
1!
2!ATLAS
=7 TeVs
-1 L dt ~ 1.0-2.3 fb(LP 2011)
ATLAS 2010-1 L dt ~ 35 pb
(2010 Data)
2011 Preliminary
LimitssCL
LimitssCL
[GeV]Hm100 200 300 400 500 600
SM
/95%
CL lim
it o
n
1
10
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 (1.08 fbH) -1 (1.70 fbl l WWH) -1 bb (1.04 fbW/Z H, H
) -1 (1.06 fbH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
) -1 llll (1.96-2.28 fb ZZH) -1 llqq (1.04 fb ZZH)-1 (1.04 fb ll ZZH
Exp. Obs. Exp. Obs.
=7 TeVs, -1 L dt ~ 1.0-2.3 fb CLs limitsATLAS Preliminary
[GeV]Hm100 200 300 400 500 600
SM
/95%
CL lim
it o
n
1
10
Low Medium High
MH [GeV]
Not allowed below
Phys. Rept. 459 (2008)
~Excluded w/ gaps by ATLAS
LEP bound
It’s an exciting time to study Higgs physics!
Tae Min HongFuture outlook
19
Next steps• Analysis : Lower lep. PT; multivar. techn.
• Background : Improve data-derived est.
• Prepare for : LHC upgrades of lumi, √s
[GeV] HM100 200 300 400 500 600 700 800 900 1000
H+X
) [pb
]
(pp
-110
1
10
210
LHC
HIG
GS
XS W
G 2
010
=14 TeVs
H+X at
pp
=7 TeVs
H+X at
pp
[GeV] HM100 200 300 400 500 600 700 800 900 1000
H+X
) [pb
]
(pp
-110
1
10
210
LHC
HIG
GS
XS W
G 2
010
=14 TeVs
H+X at
pp
=7 TeVs
H+X at
pp
[GeV] HM100 200 300 400 500 600 700 800 900 1000
H+X
) [pb
]
(pp
-110
1
10
210
LHC
HIG
GS
XS W
G 2
010
=14 TeVs
H+X at
pp
=7 TeVs
H+X at
pp
√s = 14 TeV
√s = 7 TeV
3x increase at MH = 120
MH [GeV]
Still allowed!
Implications• Exp’t limits on MH help constrain the upper
bound on Λ, the scale of new physics
Not allowed above
Tae Min HongReferences & Thanks
20
Slide Source3 http://www.interactions.org/cms/?pid=2100&image_no=CE01554 https://twiki.cern.ch/twiki/bin/view/AtlasPublic/LuminosityPublicResults4 http://www.interactions.org/cms/?pid=2100&image_no=CE01525 From S. Kortnerʼs ATLAS Week Higgs talk on Oct. 11, 2011 (ATLAS internal)
6, 15 http://cdsweb.cern.ch/record/1385868/files/ATL-PHYS-SLIDE-2011-578.pdf6 https://twiki.cern.ch/twiki/bin/view/LHCPhysics/CrossSections
7-8 https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-131/9 E. Grossʼ talk https://indico.cern.ch/conferenceOtherViews.py?view=standard&confId=141983
9-10 http://arxiv.org/abs/1109.335711 https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-015/
11-14 https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-134/15-16 http://arxiv.org/abs/1108.5895
17 https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-135/18 https://twiki.cern.ch/twiki/bin/view/AtlasPublic/HiggsPlotsLPCCCombination19 A. Djouadiʼs paper http://arxiv.org/abs/hep-ph/0503172 Phys. Rept. 459 (2008)
Bill MurrayEilam Gross
Rami VanguriJohn Alison
Josh KunkleKétévi Assamagan
Thanks
References
to ATLAS & LHC for excellent operations. I’d also like to acknowledge my colleagues who helped me prepare for this talk: