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

see Ralf Bernhardʼs talk

ATLAS-CONF-2012-019

Closing in on the SM Higgs Boson

see Ralf Bernhardʼs talk

Really?

ATLAS-CONF-2012-019

What if...

… 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?

What if...

… 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++

Fermiophobic Higgs

arXiv:1201.3084v1

Fermiophobic H→γγ : Benchmark Scenario

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)

Fermiophobic H→γγ : Analysis

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)

Fermiophobic H→γγ : Exclusion Limits

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)

Fermiophobic H→γγ : Exclusion Limits

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)

Neutral Higgs

MSSM Higgs Sector

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

MSSM Higgs → ττ : Selection

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

MSSM Higgs → ττ : Background Estimation

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)

MSSM Higgs → ττ : Results

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)

MSSM Higgs → ττ : Exclusion Limits

cross section x BR tanβ-mA plane

ATLAS-CONF-2011-132 (1.06 fb-1)

Charged Higgs

Charged Higgs : Overview

considered channels:

for mH+ < mtop :