BSM Higgs Boson Searches with ATLASmoriond.in2p3.fr/QCD/2012/SundayAfternoon/Kroseberg.pdfDecays to...
Transcript of BSM Higgs Boson Searches with ATLASmoriond.in2p3.fr/QCD/2012/SundayAfternoon/Kroseberg.pdfDecays to...
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012 1
Jürgen KrosebergUniversity of Bonn
on behalf of theATLAS collaboration
BSM Higgs Boson Searches with ATLAS
Rencontres de Moriond - QCD and High-Energy Interactions
La Thuile , March 10-17 2012
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Closing in on the SM Higgs Boson
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see Ralf Bernhardʼs talk
ATLAS-CONF-2012-019
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Closing in on the SM Higgs Boson
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see Ralf Bernhardʼs talk
Really?
ATLAS-CONF-2012-019
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
What if...
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… the Higgs-boson couplings are different from the SM ones?… this is only one of several SUSY (MSSM)Higgs bosons?… an even more complex Higgs sector is realized in nature?
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
What if...
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… the Higgs-boson couplings are different from the SM ones?… this is only one of several SUSY (MSSM)Higgs bosons?… an even more complex Higgs sector is realized in nature?
fermiophobic Higgs
MSSM neutral Higgs
Charged Higgs H+
Doubly charged H++
e.g.
e.g.
e.g.
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
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Fermiophobic Higgs
arXiv:1201.3084v1
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Fermiophobic H→γγ : Benchmark Scenario
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Decreased coupling to some or all fermions in Higgs doublet and triplet modelsHere: simple benchmark scenario without any Higgs-fermion coupling and SM coupling to gauge bosonsProduction via Vector-Boson Fusion and associated VH productionDecays to γγ, WW, ZZ, ZγHere: focus on γγ (enhanced w.r.t. SM for light(!) Higgs)
arXiv:1101.0593v3
ATLAS-CONF-2012-013 (4.9 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Fermiophobic H→γγ : Analysis
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high pTt
low pTtselect events with 2 isolated photons with pT > 40/25 GeVdi-photon mass:100 GeV < mγγ < 160 GeV9 analysis categories based on
presence of γ conversionsγ calorimeter impact pointpTt: di-photon transverse momentum orthogonal to the di-photon thrust axis in the transverse plane
signal mγγ model: “Crystal Ball” + wide Gaussianbackground mγγ model:exponential
ATLAS-CONF-2012-013 (4.9 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Fermiophobic H→γγ : Exclusion Limits
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observed mH exclusion:[110.0,118.0], [119.5,121.0]expected mH exclusion:[110.0,123.5]
ATLAS-CONF-2012-013 (4.9 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Fermiophobic H→γγ : Exclusion Limits
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observed mH exclusion:[110.0,118.0], [119.5,121.0]expected mH exclusion:[110.0,123.5]
largest excess from BG-only hypothesis at mH =125.5 GeV1.6σ (with look-elsewhere)
ATLAS-CONF-2012-013 (4.9 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
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Neutral Higgs
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
MSSM Higgs Sector
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MSSM: minimal super-symmetric extension of SMrequires 2 Higgs doublets → 5 Higgs bosons:Ф = h, H0, A ; H+,H- number of parameters can be reduced with additional assumptions, e.g. to mA, tanβenhanced couplings to b and tau in large regions of the parameter space (in particular high tanβ)
multivariate identificationJ. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
τ-Lepton Decays
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τ decay
QCD jet
hadronic tau decays:narrow, collimated jetisolated energy deposits and tracks large electromagnetic component low track multiplicity (1 or 3)high leading-track momentum fraction
full reconstruction
with “missing mass calculator” (MMC)
effective mass
inv. lepton-ETmiss mass
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
MSSM Higgs → ττ : Selection
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τlτl τlτh τhτh2-τhad trigger2 τhad with pT > 45 GeV andpT > 30 GeVopposite chargeslepton vetoETmiss > 25 GeV(QCD)
hadron-hadronisolated e / µ with pT > 25 / 20 GeVexactly one τhad with pT > 20 GeVopposite chargesdilepton veto (Z, top)ETmiss > 20 GeV (QCD)mT < 30 GeV (W)
1 isolated e with pT > 25 GeV1 isolated µ with pT > 20 GeVopposite charges(sum of lepton pT and ETmiss) < 120 GeV,ΔΦe,µ > 2.0 GeV(top, WW, ZZ)
lepton-hadronelectron-muon
visible mass
invariant mass of visible τ decay products
(NIM A654 (2011) 481)
ATLAS-CONF-2011-132 (1.06 fb-1)
ττ mass reconstruction
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
MSSM Higgs → ττ : Background Estimation
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Use mainly data-driven methods, e.g.Z/γ* →ττ from τ-embedded Z/γ* →μμ dataQCD jet background from same-sign-charge, low-MET, and/or anti-isolated lepton samplesW+jets normalization from high-mT data sample (and/or same-sign charge sample - after correction)
ATLAS-CONF-2011-132 (1.06 fb-1)
Wl
ν
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J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
MSSM Higgs → ττ : Results
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τlτl τlτh τhτhelectron-muon lepton-hadron
visible mass
hadron-hadron
effective mass MMC mass
consistent with predicted background yield+shape
ATLAS-CONF-2011-132 (1.06 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
MSSM Higgs → ττ : Exclusion Limits
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cross section x BR tanβ-mA plane
ATLAS-CONF-2011-132 (1.06 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
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Charged Higgs
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs : Overview
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considered channels:
for mH+ < mtop :
ATLAS-CONF-2012-011 (4.6 fb-1)
selection:1 electron or 1 muon withpT > 25 GeV / pT > 20 GeVat least 4 jets (2 of them b-tagged)with pT > 20 GeV ETmiss > 40 GeV (>20 GeV for small φl,miss) event kinematics consistent with signal topology
discriminating variables:
related to invariant mass of b jet and lepton from same top decay
lower bound on charged (W or H) boson mass from top decay
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs : Lepton + Jets
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ATLAS-CONF-2012-011 (4.6 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs : Tau + Lepton
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selection:1 electron or 1 muon withpT > 25 GeV / pT > 20 GeV1 hadronic tau decaywith pT > 20 GeV opposite chargeat least 2 jets (1 of them b-tagged)with pT > 20 GeVsum of primary-vertex track pT: ΣpT > 100 GeV
discriminating variable:ETmiss
ATLAS-CONF-2012-011 (4.6 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs : Tau + Jets
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selection:Tau + Etmiss trigger1 hadronic tau decaywith pT > 40 GeV ETmiss > 65 GeV
> 13
jet kinematics consistent with signal topology
discriminating variable:transverse mass mT
ATLAS-CONF-2012-011 (4.6 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs : Exclusion Limits
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lepton+jets
tau+jets combined
tau+lepton
ATLAS-CONF-2012-011 (4.6 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs : Exclusion Limits
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lepton+jets
tau+jets combined
tau+lepton
ATLAS-CONF-2012-011 (4.6 fb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
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Doubly-Charged Higgs
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
H±±→μ±μ± : Analysis
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relevant in Higgs Triplet, Little Higgs, and Left-Right Symmetric modelsselect pairs of 2 same-sign-charge muons withpT > 20 GeVlook for resonance in di-muon mass spectrumno significant excess over background-only prediction found
arXiv:1201.1091 (1.6 fb-1), acc. by PRD
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
H±±→μ±μ± : Exclusion Limits
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arXiv:1201.1091 (1.6 fb-1), acc. by PRD
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Also… [not in this talk]
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H+ →csnMSSM a1→μμ
ATLAS-CONF-2011-094 (35 pb-1)
ATLAS-CONF-2011-020 (40 pb-1)
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Summary
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a number of BSM Higgs scenarios are being probed in parallel to the SM Higgs searchno indication for a BSM Higgs boson yetsearches continue with more data and improved methodsstill significant room for BSM Higgs discoveries for the year ahead
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012 30
Backup Material
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Fermiophobic Higgs
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J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
The Missing Mass Calculator
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split missing Et into two vectors pmis1,2 (→ neutrinos)kinem. constraints
scan free parameters and weight with expected probability to come from τ decaytake maximum of obtained di-τ mass distribution
A.Elagin, P.Murat, A.Pranko, A.Safonov arXiv:1012.4686 ; NIM A654 (2011) 481
e.g.
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
τ Embedding (e.g. for Z → ττ Modeling)
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select Z → μμ data eventsremove muon tracks and nearby calorimeter cellssimulate stand-alone Z → ττ decays such that simulated τ four-momenta are the same as original muons ones (after mass correction)merge into single hybrid eventre-reconstruct objects and missing Et
reliable model of Z → ττ background shape essential (for low-mass Higgs)desirable to use real data but cannot select Z → ττ signal-freeuse Z → μμ data as starting point (≈ signal-free due to small H-μ coupling)
underlying event, pileup, hadronic activity, … from data
J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012
Charged Higgs Candidate Event
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J. Kroseberg BSM Higgs Searches with ATLAS Moriond QCD 2012 35
H±±→μ±μ± : Exclusion Limits