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MSSM Higgs searches at the LHC
Bruno LenziCEA - SaclayOn behalf of ATLAS and CMS collaborations
1
MCTP Spring Symposium on Higgs Boson PhysicsAnn Arbor, Michigan, USA
May 14th 2010
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Outline
• Introduction
• LHC, ATLAS and CMS
• The MSSM Higgs sector
• Neutral Higgs boson searches
• Charged Higgs boson searches
• Conclusions
2
Results for , from (unless indicated otherwise):
• Expected Performance of the ATLAS Experiment, Detector, Trigger and Physics (CERN-OPEN-2008-020)
• CMS Physics Technical Design Report Vol.II (CERN/LHCC 2006-021)
√s = 14TeV
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
• The LHC is running!
• At 7 TeV, with increasing luminosity
• Experiments taking data
3
LHC, ATLAS and CMS
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Outline
ATLAS/CMS Optimal for Higgs Searches
Good, Hermetic Calorimetry: Missing ET Measurement, Jet Reconstruction up to |η| < 4.9.
Powerful Particle Identification
∼ 97% Muon Efficiency, Cleanest Identification∼ 80% Electron Efficiency with Jet Rejection of 105
∼ 80% Photon Efficiency with Jet Rejection of 103
∼ 60% b Tagging Efficiency with Light Jet Rejection of 102 (Good Vertexing)∼ 50% Hadronic τ Efficiency with Jet Rejection of 102
Excellent Electron, Photon and Muon Energy- and pT Resolution
Covered in this TalkBSM Higgs Boson Searches in the MSSM
Measurement of Higgs Boson Properties
Results Based ‘Computing System Commissioning’ Studies (ATLAS)and PTDR Vol.II (CMS)
(Unless Indicated Otherwise)
W.Mader (TU Dresden) Higgs Properties and BSM Higgs Boson Searches at the LHC
LHC, ATLAS and CMS
• Good, hermetic calorimetry
• measurement, jet reconstruction up to |η| < 4.9
• Powerful Particle Identification
• ∼ 97% Muon efficiency, cleanest identification
• ∼ 80% Electron efficiency with jet rejection of 105
• ∼ 80% Photon efficiency with jet rejection of 103
• ∼ 60% b-tagging efficiency with light jet rejection of 102
• ∼ 50% hadronic τ efficiency with jet rejection of 102
• Excellent Electron, Photon and Muon energy / Pt resolution
4
Outline
ATLAS/CMS Optimal for Higgs Searches
Good, Hermetic Calorimetry: Missing ET Measurement, Jet Reconstruction up to |η| < 4.9.
Powerful Particle Identification
∼ 97% Muon Efficiency, Cleanest Identification∼ 80% Electron Efficiency with Jet Rejection of 105
∼ 80% Photon Efficiency with Jet Rejection of 103
∼ 60% b Tagging Efficiency with Light Jet Rejection of 102 (Good Vertexing)∼ 50% Hadronic τ Efficiency with Jet Rejection of 102
Excellent Electron, Photon and Muon Energy- and pT Resolution
Covered in this TalkBSM Higgs Boson Searches in the MSSM
Measurement of Higgs Boson Properties
Results Based ‘Computing System Commissioning’ Studies (ATLAS)and PTDR Vol.II (CMS)
(Unless Indicated Otherwise)
W.Mader (TU Dresden) Higgs Properties and BSM Higgs Boson Searches at the LHC
EmissT
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
MSSM Higgs sector
• Two Higgs doublets, five physical states
• three neutral: h, A and H
• two charged: H±
• Two parameters at tree level
• Mass of the CP-odd boson: mA
• Ratio of the v.e.v.s: tan β
• Large loop corrections
• mh < mZ becomes mh ≲ 130 GeV
• Fixed in benchmark scenarios (mh-max used in most of the results)
• Masses
• Couplings (for large tan β)
• W / Z suppressed, absent for A
• Enhanced with respect to SM for 3rd generation and down type fermions
• h is SM-like for large mA
5
Carena, Heinemeyer, Wagner, WeigleinEur. Phys. J. C26 (2003) pp. 601-7
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Neutral Higgs bosons: production and decays
• Production
• Decay modes (typical values for the interesting regions of the parameter space)
• bb with BR ~ 90%
• τ+τ- with BR ~10%
• μ+ μ- with BR ~ 0.03%
• SUSY particles if allowed
• Mass degeneracy
• Of at least two of them in most of parameter space
• Handled by summing cross sections for searches
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g
g
φ
g
g
b
φ
b̄
b
b̄
φ
b
g
φ
b
g
q
q̄
b
φ
b̄
(φ = h, H, A)Gluon fusion b-quark associated production: dominant at large tan β
Overwhelmed by QCD backgrounds
Possibilities in leptonic and hadronic final states
Clean signature, excellent mass resolution, low yield
Depends strongly on additional parameters
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Neutral Higgs searches:
• Motivation
• Clean signal with excellent mass resolution (3% against 20% for ττ)
• Potential to distinguish between h, H and A and provide measurement of tan β (from width)
• Sensitivity for both gluon fusion (ATLAS) and b-associated production (ATLAS / CMS)
• Drawback: small BR (enhanced for high tan β)
• Backgrounds
• Dominant: Drell-Yan Z ( + jets)
•
• WW / ZZ very small
• Can be estimated from data using
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h/H/A→ µ+µ−
ATLAS / CMS
tt̄→ bb̄µ+µ−νν̄
µ+µ−, e+e−, e±µ∓
Mean 4±Sigma 4.8e−03± 6.3
(GeV)−µ+µm
100 150 200 250 300 350 400
En
trie
s
0
100
200
300
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600
700
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900 ATLAS
Mean 4e−03± 199.6 Sigma ±
µµbbA −>
= 200 GeVAm
) = 30βtan(
Mean 5e−03± 199.6 Sigma 5.5e−03± 6.3
(GeV)−µ+µm
100 150 200 250 300 350 400
En
trie
s
0
100
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Mean ±Sigma ±
µµgg−> A −>
= 200 GeVAm
) = 30βtan(
ATLAS
[GeV]ττm0 50 100 150 200 250 300
Arbi
trary
Uni
ts
0
(130 GeV)ττ→H
Gaussian fit
= 24.6 GeVσ
= 119.4 GeVµ
ATLAS
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
(GeV)missTE
0 50 100 150 200310×
Nor
mal
ized
to u
nity
0.00
0.05
0.10
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0.20
0.25
0.30
0.35 = 200 GeV
AbbA, mZ+light jetsZ+ b jetsttZZWW
ATLAS
Neutral Higgs searches:
• Event selection
• Trigger on single-mu or di-muons (> 90% efficiency)
• High-Pt isolated muon(s) (20 GeV)
• Background reduction
• Cuts on , jet activity and angle between muons to reject tt and WW
• B-tagging requirements
• ATLAS: two independent optimizations
• 0 b-jet, dominated by Z + jets
• ≥1 b-jets, with important contribution from tt
• CMS:
• Two different strategies to increase efficiency for high and low-Pt b-jets
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h/H/A→ µ+µ−
ATLAS / CMS
EmissT
0 b-tagged jet ≥ 1 b-tagged jets
(GeV)µµm150 200 250 300 350
310×
Entr
ies
/ (4
GeV
)
1
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510
150 200 250 300 350
310×1
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bbA Z+l jets
Z+b jets
WW tt
ZZ
=150 GeVAm
=200 GeVAm
=300 GeVAm
a)ATLAS
(GeV)µµm150 200 250 300 350
310×
Entr
ies
/ (4
GeV
)
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510
150 200 250 300 350
310×1
10
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510 bbA Z+l jets
Z+b jets
WW tt
ZZ
=150 GeVAm
=200 GeVAm
=300 GeVAm
b)ATLAS
L = 30 fb-1
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
)2 (GeV/cAM160 180 200 220 240
)2 (GeV/cAM160 180 200 220 240
βta
n
20
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-1CMS, 30 fb
scenariomaxhm
2 = 1 TeV/cSUSYM2 = 200 GeV/c2M
2 = 200 GeV/cµ2 = 800 GeV/cgluinom
SUSY = 2 MtStop mix: X
100 150 200 250 300 350 400
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-1CMS, 30 fb
2 = 1 TeV/cSUSYM2 = 200 GeV/cµ
2 = 200 GeV/c2M
SUSY M6 = tX
Neutral Higgs searches:
• Discovery potential
• Low to intermediate masses for tan β > 20
• Sensitivity to tan β from mμμ peak width
• Systematic uncertainties
• Theoretical (~ 17%)
• Experimental (5 - 12%)
• Muon reconstruction efficiency, momentum scale and resolution
• Jet energy scale and resolution
• b-tagging efficiency and fake rate
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h/H/A→ µ+µ−
ATLAS / CMS
(GeV) (GeV)AAmm5050 100100 150150 200200 250250 300300 350350 400400 450450
dis
cove
ry d
isco
very
σβ
σβ
tan
f
or
5
0
1010
2020
3030
4040
5050
6060
−1L=10 fb
maxh
−1
Combined AnalysisCombined Analysis
m − scenario
Without SystematicsWithout Systematics
L=30 fb
With Experimental SystematicsWith Experimental Systematics
Theoretical UncertaintyTheoretical Uncertainty
ATLAS
discovery contour discovery contourσσ55
tan β measurement for tan β = 30, 40, 50Discovery contour
(dashed line: no systematics)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Neutral Higgs searches:
• Final states (tau decay products)
• Leptons, leptons (ATLAS / CMS)
• Leptons, hadrons (CMS, ATLAS to appear)
• Hadrons, hadrons (CMS)
• Backgrounds
•
• QCD multi-jets in hadronic case
• + jets for leptonic decay
• Systematic uncertainties
• tau fake rates
• Jet energy scale / resolution and
• b-tagging efficiency and purity
• Tau identification
• Hadronic:
• 1 or 3 tracks,
• Isolation in tracker
• 50% efficiency with jet rejection > 100
• Leptonic:
• High-Pt isolated lepton
• mττ using collinear approximation
• Background reduction
• One or more b-tagged jets
• Jet activity (tt, W + jets), di-lepton mass (Z)
• CMS: lepton impact parameter,
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Z → e+e−/µ+µ−
Z → τ+τ−, tt̄, W + jets
EmissT
(bb̄)h/H/A→ ττ
P leadingT = 10, 20GeV
mT (�, EmissT )
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
[GeV]ττm0 50 100 150 200 250 300
Cro
ss S
ectio
n (fb
/ 15
GeV
)
05
10152025303540
[GeV]ττm0 50 100 150 200 250 300
Cro
ss S
ectio
n (fb
/ 15
GeV
)
05
10152025303540
=130 GeVAm=20βtan
→ ← ττ→Hττ→Zµµ→Z
ee→ZttbarW+jets
ATLAS
Neutral Higgs searches:
• Motivation
• Leptons to trigger on
• Lower backgrounds
• Z + jets and tt mainly
• Event selection
• ATLAS: Cut on di-lepton mass against
• CMS: Displaced lepton impact parameters
• Jet veto against tt
• One or more b-tagged jets (analysis with no b-tagging for early data)
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(bb̄) h/H/A→ ττ → 2�4ν
ATLAS ( ) / CMS ( )eµ
Z → e+e−/µ+µ−
2�
)2 (GeV/cττm0 50 100 150 200250 300 350400 450 500
-1 for
30 fb
2E
vents
/25 G
eV
/c
0
5
10
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45 CMS
+Xµe→ττ→H/A
-max scenariohm2 = 200 GeV/cAm
= 25βtanSignal
*γZ/
tt
Backgr
(b)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
/ GeVAm150 200 250 300 350 400 450
βta
n
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(tt) Uncertaintyσ+10%
Theoretical Uncertainty
ATLAS -1=14 TeV, 30 fbs
scenariomaxhm
ν 2 l + 4 →ττ→bb h/H/A
Discoveryσ5
Neutral Higgs searches:
• Discovery potential
• Best at low masses
• Decreases quickly with mass
• High tan β needed
• Systematic uncertainties
• shape and normalization from data
• tt yields
• Jet energy scale and resolution
• b-tagging efficiency
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(bb̄) h/H/A→ ττ → 2�4ν
Z → τ+τ−
)2(GeV/cm100 150 200 250 300 350 400 450 500
!tan
10
20
30
40
50
Excluded by LEPExcluded by LEP
Full simulationsystematic uncertainties
Excluded by LEP
-1CMS, 30 fb
2 = 200 GeV/c2
, M2 = 200 GeV/Cµ
2 = 1 TeV/cSUSY
, M2 = 2 TeV/ctA
Full simulation, with
Fast simulation
+Xµe"##"H/A
Figure 25: The 5 -discovery reach for heavy neutral Higgs bosons H and A decaying via to e+ final state.The dots give the 5 limit for the studied values of Higgs mass. The fast simulation result is also shown.
simulation results [5] are shown for comparison. The main difference comes from updated signal and backgroundcross sections and worse than expected MET and mass resolution with more background events in the mass win-dow. The cuts are, however, more optimized. The uppermost curve shows the discovery region with the effect ofthe systematic background uncertainty taken into account. The systematic uncertainties decrease the explorableregion.
N +N N Significance(meas.) (MC) = 0% 12%
m = 140 GeV/ , tan = 20 100 - 200 GeV/ 225 107 9.9 7.3m = 200 GeV/ , tan = 20 140 - 250 GeV/ 163 109 4.8 3.1m = 250 GeV/ , tan = 20 160 - 380 GeV/ 244 204 2.7 1.4
Table 5: Number of measured events in given mass windows and estimated number of background events for30 fb and statistical significance calculated with Poisson statistics.
8 ConclusionsThe Higgs boson discovery potential in channel with Higgs boson produced in associationwith two b quarks is studied with full simulation. The tagging of one associated b jet is used to suppress the back-grounds. The Higgs boson mass is reconstructed exploiting the collinear neutrino approximation. The 5 coverageis updated and the effect of systematic errors included. The systematic uncertainties decrease the discovery reach.The largest component in the systematic errors is the uncertainty of the calorimeter energy scale.
The best strategy to improve these results is to improve the MET measurement. The mass resolution dependsstrongly on the quality of the MET measurement. Smaller width of the mass peak would decrease the number ofbackground events within the mass window. It would also allow separating the Higgs mass peak from the Z peak,and make fitting the signal and background a realistic possibility. The mass width can, however, be improved byselecting events with harder b jets as it results in better defined MET. The signal, for which the associated jets aresoft, would be suppressed though, and optimization gives better results for low jet cut. For the same reason nostrong cut is used, although improving the mass resolution that way is possible.
The optimization of b tagging gave best results with very loose discriminator cuts. Despite the potential newbackgrounds, this is hinting that a Higgs search strategy with no b tagging may be possible. If events with noassociated jets are selected, the background is efficiently suppressed while the is enhanced. The signalwould consist of Higgs bosons produced via loop mediated gluon fusion in addition to associated production
with no successfully reconstructed jets. This approach remains yet to be studied.
14
(modified Z → µ+µ−)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
)2 (GeV/cττm0 100 200 300 400 500 600 700 800
-1 fo
r 30
fb2
Eve
nts/
25 G
eV/c
0
10
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50CMS
-jet + Xτe+→ττ→H/A2 = 200 GeV/cAm
= 20βtan
2 = 1 TeV/cSUSY
, M2 = 2 TeV/ctX
2 = 200 GeV/c2
, M2 = 200 GeV/Cµ
ee→*γZ/
Signal
Backgr
Neutral Higgs searches:
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(bb̄)h/H/A→ ττ → (e/µ) had
CMS
e + jets
μ + jets
• Motivation
• Good BR and lepton for trigger
• Backgrounds
• tt, single top, Z + jets, W + jets, QCD
• Systematic uncertainties
• b-tagging, jet energy scale, lepton ID
• Discovery potential
• Low to intermediate masses at relatively low tan β
• Challenging for high masses
]2 [GeV/cτ τm0 200 400 600 800 1000
]2/ 2
0 [G
eV/c
-1E
vent
s fo
r 20
fb
0
10
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40
50
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70 Background)=20,βSignal+Bkg. for tan(
2=200 GeV/cAm)=30,βSignal+Bkg. for tan(
2=500 GeV/cAm
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Neutral Higgs searches:
• Motivation
• Good BR and lepton for trigger
• Backgrounds
• tt, single top, Z + jets, W + jets, QCD
• Systematic uncertainties
• b-tagging, jet energy scale, lepton ID
• Discovery potential
• Low to intermediate masses at relatively low tan β
• Challenging for high masses
14
(bb̄)h/H/A→ ττ → (e/µ) had
CMS
MSSM Higgs Boson Searches Neutral MSSM Higgs Bosons h/H/A
bbh/H/A, h/H/A → τ(lep)τ(had) (CMS)Discovery Potential
e + jets µ + jets
� good for intermediate to low mass range� (ATLAS analysis in preparation)� at high masses higher sensitivity in the fully hadronic channel
Jan Schumacher (TU Dresden) BSM Higgs Boson Searches at the LHC WIN09 9 / 23
e + jets
μ + jets
]2 [GeV/cAm
200 250 300 350 400 450 500 550 600
)βta
n(
10
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Discovery area -1for 30 fb
H max m 2 = 1000 GeV/cSUSY m 2 = 2449 GeV/cMS
t X 2 = 200 GeV/cµ 2 = 200 GeV/c2 M
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Neutral Higgs searches:
• Motivation:
• High BR ( not feasible)
• Sensitivity for high masses
• Main background: QCD multi-jets
• Estimated from data using same sign “tau’s”
• Systematic uncertainties
• Jet energy scale / resolution
• τ fake rate from tracker misalignment
15
(bb̄)h/H/A→ ττ → had had
CMS
MSSM Higgs Boson Searches Neutral MSSM Higgs Bosons h/H/A
bbh/H/A, h/H/A → τ(had)τ(had) (CMS)� Motivation
� high hadronic branching ratio� dominant h/H/A→ bb overwhelmed by QCD� τ tagging makes channel feasible� sensitivity for high masses
� Event Selection� hadronic final state, need good τ -trigger� τ identification
� isolation in tracker
� 1 or 3 tracks, hard leading track
(pt > 50GeV)
� ≈ 50% efficiency at a rejection of 100
� exactly one b-tagged jet
� Backgrounds and Systematics� QCD jets: shape from data-driven method
using signal free same-sign τs� uncertainty of τ fake rate due to
tracker misalignment� E
missT scale uncertainty 2,GeV/cAM
100 200 300 400 500 600 700 800
!tan
10
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50
-1CMS, 30 fb = h,H,A", " bb#pp
scenariomaxhm
2 = 1 TeV/cSUSYM2 = 200 GeV/c2M
2 = 200 GeV/cµ2 = 800 GeV/cgluinom
SUSY = 2 MtStop mix: X
µ e
# $$ # "
+jet
µ # $$
# "
e+jet# $$ # "
-1
jet+jet, 60 fb
# $$ # "
µµ
# "
Jan Schumacher (TU Dresden) BSM Higgs Boson Searches at the LHC WIN09 12 / 23
bb̄
2,GeV/cAM100 200 300 400 500 600 700 800
βtan
10
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-1CMS, 30 fb = h,H,Aφ, φ bb→pp
scenariomaxhm
2 = 1 TeV/cSUSYM2 = 200 GeV/c2M
2 = 200 GeV/cµ2 = 800 GeV/cgluinom
SUSY = 2 MtStop mix: X
µ e
→ ττ → φ
+jet
µ → ττ
→ φ
e+jet→ ττ → φ
-1
jet+jet, 60 fb
→ ττ → φ
µµ
→ φ
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
MSSM Higgs Boson Searches Neutral MSSM Higgs Bosons h/H/A
A/H → χ̃02χ̃
02 → 4� + E
missT
� Analysis� MSSM / mSUGRA points optimized for
lepton BR
� Backgrounds and Event Selection� 4 leptons, opposite signs and flavours� tt̄: jet multiplicity� ZZ , Zbb: Emiss
T lower bound,dilepton masses
� SUSY, EmissT upper bound, jet multiplicity
� Systematic Uncertainties� little experimental uncertainty� strongly model dependent
Jan Schumacher (TU Dresden) BSM Higgs Boson Searches at the LHC WIN09 14 / 23
• Scenarios:
• MSSM / mSugra points favoring decays to leptons
• Backgrounds: tt, ZZ, Zbb, SUSY
• Event selection:
• 4-leptons with opposite signs and flavors
• Upper and lower bounds on
• Cuts on di-lepton mass and jet multiplicity
• Systematic uncertainties
• Small from experimental side
• Strongly model dependent
Neutral Higgs searches:
16
MSSM Higgs Boson Searches Neutral MSSM Higgs Bosons h/H/A
A/H → χ̃02χ̃
02 → 4� + E
missT
� Analysis� MSSM / mSUGRA points optimized for
lepton BR
� Backgrounds and Event Selection� 4 leptons, opposite signs and flavours� tt̄: jet multiplicity� ZZ , Zbb: Emiss
T lower bound,dilepton masses
� SUSY, EmissT upper bound, jet multiplicity
� Systematic Uncertainties� little experimental uncertainty� strongly model dependent
Jan Schumacher (TU Dresden) BSM Higgs Boson Searches at the LHC WIN09 14 / 23
H/A→ χ̃02χ̃
02 → 4� + E
missT
EmissT
CMS PTDR
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
MSSM Higgs Boson Searches Charged MSSM Higgs Bosons H±
Charged Higgs Boson H±
Searches
� Motivation
� predicted by two Higgs doublet models
(e.g. MSSM)
� models with Higgs triplets (e.g. little
Higgs)
� smoking gun evidence for physics beyond
the SM
� Low Mass Case mH+ < mt
� production via t → H+b
� decay via H+ → τν
� small tan β: H+ → cs
(ATLAS analysis in preparation)
� High Mass Case mH+ > mt
� production via gg → tbH+
and gb → tH+
� decay via H+ → tb
g
g
g
b
bt
t H +
W−
g
g
b
bt
tb
W−H +
Jan Schumacher (TU Dresden) BSM Higgs Boson Searches at the LHC WIN09 15 / 23
MSSM Higgs Boson Searches Charged MSSM Higgs Bosons H±
Charged Higgs Boson H±
Searches
� Motivation
� predicted by two Higgs doublet models
(e.g. MSSM)
� models with Higgs triplets (e.g. little
Higgs)
� smoking gun evidence for physics beyond
the SM
� Low Mass Case mH+ < mt
� production via t → H+b
� decay via H+ → τν
� small tan β: H+ → cs
(ATLAS analysis in preparation)
� High Mass Case mH+ > mt
� production via gg → tbH+
and gb → tH+
� decay via H+ → tb
g
g
g
b
bt
t H +
W−
g
g
b
bt
tb
W−H +
Jan Schumacher (TU Dresden) BSM Higgs Boson Searches at the LHC WIN09 15 / 23
Charged Higgs boson: production and decays
• Light charged Higgs
• Produced mainly through top decay
• Decays mostly to τν
• Heavy charged Higgs
• Produced mainly by gb or gg
• Decays mostly to tb (or τν)
• Backgrounds
• tt, W + jets, single top, QCD
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(mH+ < mt)
(mH+ > mt)
!tan0 10 20 30 40 50
b)± H
"B
R(t
-410
-310
-210
-110
1 2=140GeV/c+Hm2=150GeV/c+Hm2=160GeV/c+Hm2=170GeV/c+Hm
(a)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Light charged Higgs boson searches
• Final states:
• τ → hadrons, W → qq (ATLAS) ➝ High yields
• τ →ℓν, W → qq (ATLAS) ➝ Isolated lepton from τ
• τ →hadrons, W →ℓν (ATLAS / CMS) ➝ Isolated lepton from W
• Backgrounds
• tt, W + jets, QCD, single top
• Common features
• Presence of tau, large , b and light jets
• ATLAS: H+ transverse mass reconstruction
• Systematic uncertainties
• tt cross section, estimated from data (ATLAS)
• b / τ-tagging efficiencies and fake rates
• Jet energy scale
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(mH+ < mt)
EmissT
Top Transverse Momentum [GeV] 0 50 100 150 200 250 300 350 400
Arb
itra
ry U
nits
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0.18
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bjjντ b→tReal t
bjjντ b→tScaled t
tt̄ estimation from µνbµνb
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Light charged Higgs boson searches
• τ → hadrons, W → qq (ATLAS)
• Trigger on tau + ( + jets)
• τ-jet, 2 b-tagged jets, at least 2 more
• Veto on isolated lepton, tt reduced with likelihood discriminant
• τ →lν, W → qq (ATLAS)
• Trigger on lepton +
• Isolated lepton, at least 4 jets, 2 b-tagged, large
• Hadronic W and top mass reconstruction
• τ →hadrons, W →lν (ATLAS / CMS)
• Trigger on lepton (+ , ATLAS)
• At least 3 jets, 1 b and 1 τ-tagged (or more ATLAS)
• Large , isolated lepton
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(mH+ < mt)
EmissT
2,GeV/c+H
M90 100 110 120 130 140 150 160 170 180
βta
n
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2 = 200 GeV/cµ2 = 1000 GeV/cµ
-1CMS, 30 fb νντ → ±, H± tbH→pp 2 = 175 GeV/ctm
scenariomaxhm
2 = 1 TeV/cSUSYM2 = 200 GeV/c2M
SUSY = 0.8 Mgluinom
SUSY = 2 M
tX
(arX
iv:0
804.
1228
v1)
90 100 110 120 130 140 150 160 170
5
10
15
20
25
30
35
40
45
50
55
60
mH+ [GeV]
tanβ
5σ discovery sensitivity
Scenario B ATLAS
30 fb−1
10 fb−1
1 fb−1
τ →
had
rons
, W →
mh-m
ax,μ
= 2
00 G
eV
EmissT
EmissT
EmissT
EmissT
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
)2) (GeV/cmissT
jet, Eτ(Tm0 50 100 150 200 250 300 350
-1 fo
r 30
fb2
Eve
nts
/ 30
GeV
/c
0
5
10
15
20
25
30
qqb→, t ± tbH→ gg
τν hadrons + → τ, τντ → ± H2 = 170 GeV/c±H m
CMS
signal
total background
Heavy charged Higgs boson searches
• Final states
•
• Similar to light charged Higgs analysis
• CMS: Requires hard tau and jets
• ATLAS: Likelihood discriminant based on tau, jets and
•
• 5 or 6 jets, 3 or 4 b-tagged
• Constraints on W and t mass
• Difficulties from combinatorics, likelihood used (ATLAS)
20
(mH+ > mt)
EmissT
ATLAS / CMS(gg → tbH+ and gb→ tH+)
H+ → tb (W → qq and the otherW → �ν) [GeV]+Hm
0 100 200 300 400 500 600 700 800 900 1000
Cro
ss S
ectio
n [fb
/ 50
GeV
]
0
2
4
6
8
10
12 = 200 GeV+Hm
Signal + Background
+ jetstt (QCD)b btt (ElW)b btt
ATLAS
[GeV]+Hm0 100 200 300 400 500 600 700 800 900 1000
Cro
ss S
ectio
n [fb
/ 50
GeV
]
0
2
4
6
8
10
12 = 250 GeV+Hm
Signal + Background
+ jetstt (QCD)b btt (ElW)b btt
ATLAS
[GeV]+Hm0 100 200 300 400 500 600 700 800 900 1000
Cro
ss S
ectio
n [fb
/ 10
0 G
eV]
0
2
4
6
8
10
12 = 400 GeV+Hm
Signal + Background + jetstt
(QCD)b btt (ElW)b btt
ATLAS
[GeV]+Hm0 100 200 300 400 500 600 700 800 900 1000
Cro
ss S
ectio
n [fb
/ 10
0 G
eV]
0
2
4
6
8
10
12 = 600 GeV+Hm
Signal + Background + jetstt
(QCD)b btt (ElW)b btt
ATLAS
H+ → τν (W → qq, τ → hadrons)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Heavy charged Higgs boson searches
21
(mH+ > mt)
ATLAS / CMS
mH+ [GeV]
tanβ
5σ discovery sensitivity
ATLASScenario B
200 250 300 350 400 450 500 550 600
5
10
15
20
25
30
35
40
45
50
55
60
30 fb−1
10 fb−1
1 fb−1
• Final states
•
• Similar to light charged Higgs analysis
• CMS: Requires hard tau and jets
• ATLAS: Likelihood discriminant based on tau, jets and
•
• 5 or 6 jets, 3 or 4 b-tagged
• Constraints on W and t mass
• Difficulties from combinatorics, likelihood used (ATLAS)
EmissT
(gg → tbH+ and gb→ tH+)
H+ → tb (W → qq and the otherW → �ν)
H+ → τν (W → qq, τ → hadrons)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Charged Higgs boson expected discovery potential
• Good sensitivity at low masses and/or high tan β, dominated by
• Difficult in intermediate tan β
• Decays to SUSY particles might be an alternative
22
H+ → τν
2,GeV/cAM100 200 300 400 500 600
βta
n
10
20
30
40
50
60
70
80
2 = -1000 GeV/cµ2 = -200 GeV/cµ
2 = 200 GeV/cµ2 = 1000 GeV/cµ
scenariomaxhm
2 = 1 TeV/cSUSY
M2 = 200 GeV/c2M
SUSY = 0.8 Mgluinom
SUSY = 2 MtX
mH+ [GeV]ta
nβ
5σ discovery sensitivity
ATLASScenario B
90 110 130 150 170 200 250 400 600
5
10
15
20
25
30
35
40
45
50
55
60
30 fb−1
10 fb−1
1 fb−1
CDF Run IIExcluded95% CL
mh-max,μ = 200 GeV, Δb effects includedCMS, L = 30 fb-1 (arXiv:0804.1228v1)(black lines include Δb effects)
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010
Conclusions
• Good discovery potential for MSSM Higgs at LHC
• At least one Higgs boson will be found if present
• Large regions of parameter space can be covered, some need high statistics
• Neutral Higgs boson
• Sensitivity dominated by , coverage up to mA ~ 800 GeV
• helps at low masses and gives narrow peak
• Charged Higgs boson
• Good sensitivity at low masses and high tan β with
23
h/H/A→ τ+τ−
h/H/A→ µ+µ−
H+ → τν
Backup slides
24
Bruno Lenzi - CEA Saclay MSSM Higgs searches at LHC MCTP Spring 2010 25
Point m0 (GeV/c2)
m1/2 (GeV/c2)
A0 (GeV/c2)
tanβ sign(μ)
CMS A
CMS B
CMS C
ATLAS A
ATLAS B
60 175 0 10 +
80 200 0 5 +
50 150 0 5 +
400 165 0 20 +
125 165 0 20 +
MSSM scenarios studied
Scenario OBS mt (GeV) MSUSY (GeV)
μ (GeV)
M2, M3 (GeV) At
A
B
H+ to SUSY suppressed 175 500 200 1000 1000
mh-max 170 1000 200 200, 800
Xt(2000) + μ/tan β
ATLAS, charged Higgs
Neutral Higgs to SUSY particles, mSUGRA
Set M1 (GeV) M2 (GeV) μ (GeV)
msl, mstau (GeV)
msg, msq (GeV)
1
2
90 180 -500 250 1000
100 200 -200 150, 250 800, 1000
Neutral Higgs to SUSY particles, MSSM (ATLAS)
• MSUSY : soft-SUSY breaking mass
• μ: Higgsino mixing parameter
• m1/2, M1, M2: gaugino masses
• M3: gluino mass
• m0: scalar masses
• A0: trilinear coupling
• mtXt: off-diagonal entry in stop mass matrix