ATLAS Searches in Higgs Sectors Beyond the Standard Model · ATLAS H+! t b;˝+ Sensitivity ATLAS...

ATLAS Searches in Higgs Sectors Beyond the

Standard Model

Chris Potter for the ATLAS Collaboration

McGill University

Higgs BSM Seminar, October 2009 – p.1/27

Overview: Outline of the Talk

Outline of the Talk:

� Higgs Sectors in SUSY: Minimal SUSY (MSSM), Next-to MSSM (NMSSM)

� MSSM Neutral Higgs φ = h/A/H (SM φ → bb̄ channel not considered)

� MSSM φ Phenomenology

� Tevatron Exclusion Limits on MSSM from φ Searches� ATLAS φ → µ+µ−, τ+τ−, Invisible Sensitivity

� MSSM Charged Higgs H+

� MSSM H+ Phenomenology

� Tevatron Exclusion Limits on MSSM from H+ Searches� ATLAS H+ → tb̄, τ+ν Sensitivity� ATLAS Ongoing Studies: H+ → τ+ν, cs̄

� NMSSM Charged and Neutral Higgs

� NMSSM Motivation and Phenomenology

� Tevatron Exclusion Limits from h1 Searches� ATLAS Ongoing Studies: h1 → 2a1 → 2µ2τ and h+ → a1W

ATLAS results from CERN-OPEN-2008-020, Geneva, 2008. UOI, all ATLAS results assume√s = 14 TeV and the mh − max scenario of the MSSM. Higgs BSM Seminar, October 2009 – p.2/27

Overview: SUSY, MSSM, NMSSM

� SUSY: S. Martin, hep-ph/9709356

� Provides an elegant solution to the Hierarchy Problem of the SM.

� Predicts that gauge couplings are unified at the GUT scale.

� Provides a good candidate for Dark Matter - the neutralino χ0.

� The MSSM: S. Martin, hep-ph/9709356

� Introduces soft supersymmetry breaking term to the SUSY potential to account for thebroken symmetry.

� Reduces the number of free parameters in SUSY to a manageable number and therebyprovides a convenient benchmark for simulation studies.

� Contains two neutral scalars (h, H), one neutral pseudoscalar (A) and two chargedscalars (H+, H−).

� The NMSSM: M. Maniatis, arXiv:0906.0777v1; R. Dermisek and J. Gunion, arXiv:0811.3537

� Solves the µ-term problem in the MSSM without fine tuning by adding a single field tothe MSSM.

� Accounts for the anomalous muon magnetic moment (the MSSM cannot).

� Accounts for the combined LEP 2.3σ excess in the mbb̄ distribution from `+`−bb̄ events.

� Contains three scalars (h1, h2, h3), two pseudoscalar (a1, a2) and two charged scalars(h+, h−).


MSSM φ Phenomenology

AP+VBF: ATLAS φ → Inv.; gg Fusion: ATLAS φ → µ+µ−, Tev. φ → τ+τ−; bbφ: ATLAS and Tev.φ → τ+τ−

g

g

φ

σ(pp → bb_

h + X) [fb]

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bb_

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ATLAS H→gg

qqHWHZHttH

Left, the inclusive cross-sections for the processes bb → φ (blue hatched region) and gg → φ (redhatched region) are shown on the right-hand side. Right, cross-sections for the five productionchannels of the Standard Model Higgs boson at the LHC at 14 TeV.


Tevatron Limits on the MSSM φ

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Combined CDF and D0 limits on MSSM Higgs boson production in tau-tau final states with up to2.2 fb-1 of data (Conference Note 5980-CONF).


MSSM Neutral Higgs: φ → µ+µ− Signal

The Tevatron does not study this channel.

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Dimuon mass distribution for the bbA and gg -> A signal samples with an A boson mass of 200GeV and tan β = 30. The distributions are fitted by the Gauss function.


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Invariant dimuon mass distributions of the main backgrounds and the A boson signal at masses mA=150, 200 and 300 GeV andtanβ = 30, obtained for the integrated luminosity of 30 fb-1. B-tagginghas been applied for the event selection. The production rates of H and A bosons have been addedtogether. a) for the 0 b-jet final state and b) for the final state with at least 1 b-jet.


MSSM Neutral Higgs: φ → µ+µ− 10 fb−1 Sensitivity

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ATLAS


MSSM Neutral Higgs: φ → τ+τ− Results

ATLAS considers ee, µµ channels while the Tevatron does not; Tevatron considers τhad.

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Invariant mτ+τ− distribution for Higgs boson candidates with nominal masses as indicated in theplots. The distributions are shown after all selection cuts for tan β = 20.

H → τ+τ− tt̄ Z → τ+τ− Z → e + e− Z → µ+µ− W+jets

mA = 110 GeV 51.8 ± 3.5 39.3 ± 6.6 152.3 ± 9.5 3.9 ± 4.2 4.6 ± 4.3 17 ± 15

mA = 130 GeV 43.3 ± 3.1 32.8 ± 6.0 107.5 ± 8.8 3.6 ± 3.1 3.8 ± 4.0 21 ± 16

mA = 160 GeV 28.8 ± 1.5 71.0 ± 8.8 67.5 ± 6.3 3.6 ± 4.1 4.9 ± 4.5 16 ± 14

mA = 200 GeV 14.1 ± 0.7 80.8 ± 9.4 26.9 ± 4.0 2.8 ± 3.6 4.6 ± 4.4 20 ± 16

mA = 300 GeV 3.8 ± 0.2 102 ± 10 16.1 ± 3.1 2.2 ± 3.2 4.2 ± 4.1 19 ± 16

mA = 450 GeV 0.60 ± 0.03 93 ± 10 12.5 ± 2.7 2.0 ± 3.1 1.7 ± 2.7 18 ± 15

Accepted cross-section for all Higgs boson mass hypotheses analyzed. The cross-section in fb forsignal and background after all selection cuts is given (except for the cut on the mass window) fortan β = 20.


MSSM Neutral Higgs: φ → τ+τ− 30 fb−1 Sensitivity

/ GeVAm100 150 200 250 300 350 400 450

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95% CL. Exclusion


MSSM Neutral Higgs: VBF φ → Invisible[χ0χ0] Results

The Tevatron does not study this channel.

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VBF signal events (mH = 130 GeV) and backgrounds: η1 × η2 (left) and η1 − η2 (right).

The distribution of the reconstructed EmissT

isolation variable (I) is shown in the right hand plot andthe azimuthal angle between the tagging jets is shown in the righthand plot for the invisible Higgsboson signal (m=130GeV) and the three main backgrounds.


MSSM Neutral Higgs: AP φ → Invisible[χ0χ0] Results

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Associated production ZH with H → Invisible. Input variables used by the Boosted Decision Treefor the signal with mH = 130 GeV and the main backgrounds. Numbers are BDT rank fordiscriminatory power.

#1 #2 #3

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MSSM Neutral Higgs: φ → Invisible[χ0χ0] 30 fb−1 Sensitivity

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The Boosted Decision Tree (BDT) output vari-ables obtained after comparing half the signalevents to five different backgrounds separately,namely, from top to bottom: tt->blnublnu, WW->lnulnu, ZZ->llnunu, ZW->lllnu and Z->ll+jets.

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MSSM Charged Higgs H+ Phenomenology

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Left: expected charged Higgs boson production cross-section at√

s = 14 TeV in the MSSM for themh-max scenario. Right: charged Higgs boson branching ratios as a function of mass for themh-max scenario for tan β = 2 and three selected decay modes.

Light H+ Heavy H+


Tevatron Limits on the Charged MSSM Higgs

Phys. Rev. D 80, 051107 (2009) (left) and CDF Conference Note 9322 (right)

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Phys. Rev. Lett. 102 , 191802 (2009).

Light H+ → τ+ν Light H+ → cs̄

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MSSM Charged Higgs: H+→ tb̄ Results

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gg → tbH+ → tbtb → 4bWlepWhad: Reconstructed H+ mass. The value of tan β has beenchosen such that the pure statistical significance results in a value of 5.


MSSM Charged Higgs: H+→ τ+ν Results

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tt̄ → bH+bW− → bτlepνbqq′: (a) cos θ? distribution, (b) W transverse mass distribution, for signaland background, after selection cuts.

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tt̄ → bH+bW− → bτlepνbqq′: Transverse mass differential cross-section for signal andbackground, for tan β = 20, and for the hypothesis of (a) W, and (b) H+.


MSSM Charged Higgs: H+→ τ+ν Sensitivity

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CDF Run II Excluded 95% C.L.


H+→ τ+ν Ongoing Studies: ATL-COM-PHYS-2009-390

H+→ cs̄ in Semileptonic tt̄

The Manchester group, who were involved inthe H+ → cs̄ search at CDF, have repeatedtheir analysis on ATLAS simulated data.

]2M(dijet) [GeV/c0 20 40 60 80 100 120 140 160 180

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Di-jet mass distribution with 120 GeV/c2Higgs events assuming Br(t → H+b) = 0.1.(See CDF Note 9322).

H+→ τlepν in Dilepton tt̄

The Uppsala and McGill groups have performeda search for H+ → τlepν in Dilepton tt̄ events.They use the same variables used by the Weizmangroup for H+ → τlepν in Semileptonic tt̄ events.

)lθ(*cos-1 -0.5 0 0.5 1

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b) = 17%+ H→BR(t

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At left, the helicity angle calculated at theevent generator level for signal events (mH+ =

130 GeV) and background (blue). At right, thegeneralized transverse invariant mass for signalevents (mH+ = 130 GeV) and background (blue).Both

√s = 10 TeV studies in review at ATLAS -

preliminary results competitive with Tevatron.Higgs BSM Seminar, October 2009 – p.19/27

NMSSM: Experimental Motivation

R. Dermisek talk at CERN Theory Group, 20 Aug. 2009. Higgs BSM Seminar, October 2009 – p.20/27

NMSSM: Phenomenology I

R. Dermisek talk at CERN Theory Group, 20 Aug. 2009. Higgs BSM Seminar, October 2009 – p.21/27

NMSSM Phenomenology II

Branching ratios for h1 → 2a1, H+ → a1W+, a1 → τ+τ− and a1 → µ+µ− versus relevant massin the Ideal Higgs scenario of the NMSSM (courtesy of J. Gunion and R. Dermisek).


Tevatron Limits on the NMSSM Neutral Higgs

(GeV)aM4 6 8 10 12 14 16 18

aa) (

pb)

→ B

R(h

×h)

→p

(pσ

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10Observed limitExpected limitTheory

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(a)

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→ B

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Observed limitExpected limitTheory

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View 2, Side (Z-Y)

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nts

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BackgroundSignals

Phys. Rev. Lett. 103 , 061801 (2009)Higgs BSM Seminar, October 2009 – p.23/27

NMSSM Ongoing Progress: ATL-COM-PHYS-2009-???

Student works in progress at McGill: Miika Klemetti (left) on H+ → a1W+ → 2µW+ andCatherine Laflamme (right) on h1 → 2a1 → 2µ2τ . No public results are yet available.


Conclusion: Recap Tevatron and ATLAS Exclusion

]2 [GeV/cAm100 110 120 130 140 150 160 170 180 190 200

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Excluded by LEPObserved limitExpected limit

σ 1 ±Expected limit σ 2 ±Expected limit

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Theore

ticall

y Inac

cess

ible

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/ GeVAm150 200 250 300 350 400 450

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scenariomaxhm


95% CL. Exclusion

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β


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Conclusion: Luminosity Caveat

arXiv:0910.3612

What is the LHC Luminosity profile?Higgs BSM Seminar, October 2009 – p.26/27

Conclusion: Tevatron and ATLAS Channels

� ATLAS expected sensitivity is competitive with the Tevatron sensitivity, though actualluminosity profiles and bureaucratic throughput will determine actual sensitivity profiles.

� Limited Datasets (6.8 fb−1 delivered) at the Tevatron:

ChannelR

dtLφ → Invisible NA

φ → µ+µ− NA

H+ → a1W+ NA

H+ → τ+ν 0.9fb−1

H+ → tb̄ 0.9fb−1

φ → τ+τ− 1.0-2.2fb−1

H+ → cs̄ 2.2fb−1

h1 → 2a1 4.2fb−1

� Search Strategies at ATLAS and Tevatron are strikingly different:

� φ → τ+τ−: ATLAS does not use gg fusion; Tevatron does not use ee, µµ.� H+ → τ+ν: ATLAS relies heavily on τhadν with opposite Whad.

� A warning to ATLAS: bureaucratic efficiency and search strategies are not optimized.


ATLAS Searches in Higgs Sectors Beyond the Standard Model · ATLAS H+! t b;˝+ Sensitivity ATLAS...

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