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Beyond-the-Standard Model (BSM) Higgs Physics using the ATLAS Experiment

Beyond-the-Standard Model (BSM) Higgs Physics using the ATLAS Experiment. I . I . Tsukerman, ITEP, Moscow, Russia Russian ATLAS meeting Dubna, Russia, 22.09-23.09.2014. ITEP. LHC. Content. Introduction Charged Higgs boson searches

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Beyond-the-Standard Model (BSM) Higgs Physics using the ATLAS Experiment

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  1. Beyond-the-Standard Model (BSM) Higgs Physics using the ATLAS Experiment I.I. Tsukerman, ITEP, Moscow, Russia Russian ATLAS meeting Dubna, Russia, 22.09-23.09.2014 ITEP LHC I.Tsukerman, RussianATLAS 2014

  2. Content • Introduction • Charged Higgs boson searches • Invisible decay of neutral Higgs boson: ZH, Hinvisible • High mass scalar Higgs boson searches • Neutral MSSM Higgs boson searches • Xhhbbgg searches at low and high masses • Conclusion NEW NEW I.Tsukerman, RussianATLAS 2014

  3. Introduction Standard Model (SM-like) Higgs boson with a mass of 125 GeV was discovered by ATLAS and CMS two years ago Great success of the model, however it does not explain many things: particle mass hierarchy, dark matter, dark energy, baryon asymmetry of the Universeand have problems with unification of interactions Many extensions of the SM proposed by theorists were rejected after this discovery, however some of them are OK. One of the simplest cases is additional Higgs doublet, where we have: More on models see on backup slides I.Tsukerman, RussianATLAS 2014

  4. Charged Higgs boson searches • H± in MSSM. Relation between mtop and MH±dictates both production mode and decay channels • Charged Higgs boson in 2HDM cascade Low mass H± : H ±bWb final state H ±cs at tan b <1 H ±tnt at tan b >1 High mass H± : tH± final state H ±tnt is OK • A0 is assumed to be too heavy • h0 is 125 GeV Higgs boson • Final state is WWbb as for tt-background I.Tsukerman, RussianATLAS 2014

  5. Searches for H+cs in tt events at 7 TeV EPJC 73 6 (2013) 2465 • Search mass range: 90-150 GeV • Signature: isolated, high pT lepton, two energetic jets with mjj = m(H) and large ETmiss • Backgrounds: tt, single top, dibosons, Z+jets and multijets tt-state, one top goes to bWbln, second top decays to bHbcs 95% CL on B(tH+b) lies between 1%-5% depending on mass of charged Higgs boson No deviation from the SM is seen I.Tsukerman, RussianATLAS 2014

  6. Exclusion limits for H+assuming B(H+tn)=1 Low mass H+ limits ATLAS-CONF-2013-090 MSSM mhmax scenario: tan b>1 is excluded for 100-140 GeVmH+ 95% CL on B(tH+b) is between 0.24-2.1% High mass H+ limits MSSM mhmax scenario: tan b>47-63 is excluded for 200-300 GeVmH+ 95% CL on s(H+) lies between 0.017-0.9pb I.Tsukerman, RussianATLAS 2014

  7. Searches for cascade H0WH±h0WWbbWW • Search mass range: 225-925 GeV for mH+, 325-1025 GeV for mH0 • Signature: one isolated high-pT lepton (from W), four high-pT jets (2 b-jets with mjj=mh0), large ETmiss and mTWdepending on lepton flavour • Assumption: pTn = ETmiss • Backgrounds: tt (dominant), also W+jets, Z/g* +jets, single top, dibosons and multijets • Multivariate analysis based on seven kinematical variables to discriminate signal from tt-background PRD89 (2014) 032002 no deviations from the SM are seen 95% CL limits on s×BR range from 0.065 pb to 43 pbdepending on mH± and mH0 at mh0 =125 GeV I.Tsukerman, RussianATLAS 2014

  8. ZH, Hinvisible results PRL 112 (2014) 201802 • Search mass range: 110-400 GeV • s(Zh, h4n)0.4 fb at 8 TeV (for 125 GeV) in SM, look for possible enhancements due to BSM processes • Signature: pair of isolated, high pT same flavour leptons with mll =m(Z), large ETmiss • Backgrounds (BGR) • ZZ,WWllnncontinuum, WZ, tt, single top; also h0ZZ or WW • 180 events are seen after selections, • in agreement with SM expectations. • No significant excess above BGR • is observed over the whole mass range • ETmiss distributions are used to extract the limits on sZH× BR(Hinvisible) BR(Hinv) is <75% at 95% CL I.Tsukerman, RussianATLAS 2014

  9. HWWℓnℓnSM, NWA exclusion at high mass • Search mass range: 260-1000 GeV • s ×BR decreases from 300 fb at 260 GeV to 4 fb at 1000 GeV mass for 8 TeV • Selection criteria optimized for high-mass Higgs boson searches; cut-based analysis • Only WWenmndecay channel used • Backgrounds: h0WW* at 125 GeV in addition to conventional SM processes • SM-like (Complex Pole Scheme (CPS) • with interference) and Narrow Width Approximation (NWA) Higgs boson lineshapes considered CPS NWA Observed exclusion: below 642 GeV at 95% CL for SM-like Higgs, a bit higher for NWA Higgs ATLAS-CONF-2013-067 I.Tsukerman, RussianATLAS 2014

  10. HWWℓnℓnSM/NWA exclusion at high mass-2 ATLAS-COM-PHYS-2014-193 • New analysis where ITEP participates is close to publication • Search mass extended to 200-1000 GeV,WWenen , mnmnchannels added • Complete optimization of selection for high-mass Higgs searches I.Tsukerman, RussianATLAS 2014

  11. HWWℓnℓnSM exclusion at high mass ATLAS-COM-PHYS-2014-193 I.Tsukerman, RussianATLAS 2014

  12. HWWℓnℓnNWA exclusion at high mass ATLAS-COM-PHYS-2014-193 I.Tsukerman, RussianATLAS 2014

  13. HZZ*4ℓexclusion at high mass ATLAS-CONF-2013-013 • Search mass range: 200-900 GeV • s×BR 5.5 fb at 8 TeV for mH=300 GeV, • <1 fb at 600 GeV for SM-like H low statistics • Signature: two pairs of isolated, high pT leptons (mℓℓ is compatible with m(Z) for both pairs). ggF, VBF and VH-like categories • Backgrounds (BGR) • qq,gg ZZcontinuum (irreducible) • tt, Z+jets/Drell-Yan (reducible) No deviation from the SM is seen Observed exclusion: below 650 GeV at 95% CL for SM-like Higgs (CPS) in ggF mode, very narrow exclusion region in VBF mode I.Tsukerman, RussianATLAS 2014

  14. Hgg exclusion at high mass arXiv 1407.6583 NEW • Search mass range: 65-600 GeV • Signature: two high-pT isolated g • (Reconstruction of M(gg) with high resolution) • Backgrounds (BGR) • qq,gg gg continuum, h0gg (irreducible) • jet, jet jet, Drell-Yan (reducible): • Powerful g ID to suppress jetp0fake g • 65 GeV<mX<110 GeV and • 110 GeV<mX<600 GeV regions • to increase sensitivity • 3 categories in low-mass region • depending whether g is converted • to reduce Drell-Yan BGR No deviation from the SM is seen 95% CL exclusion of fiducial cross section × BR(Hgg) shown; some 2s –fluctuations observed I.Tsukerman, RussianATLAS 2014

  15. MSSM ftt searches ATLAS-CONF-2014-049 NEW • Search mass ranges: 90-200 GeV and 200-1000 GeV • Signatures: two reconstructed t with mtt close to mf; em, lep-had and had-had final states depending on decays of t-pair • Backgrounds (BGR) • Ztt, Zℓℓ, top, diboson, fake leptons with relative rates depending on tt state • Mass reconstruction using: • 1) MMC approach (pTmiss is only due to n) • 2) tt transverse mass (good for had-had) • No significant excess above BGR is seen Production mechanisms of f=h/H/A Analysis is similar to SM httsearches but optimized for different production mechanisms and Higgs boson masses Data/MC:OK I.Tsukerman, RussianATLAS 2014

  16. MSSM fttexclusion limits ATLAS-CONF-2014-049 NEW • Best tan(b) constraint for combined search excludes tan(b)>5.4 for • mA=140 GeV; for high mass tan(b)>36 is excluded for mA=800 GeV • Note. MSSM mhmaxscenario with MSUSY =1 TeV is considered here. • mA<160 GeV is excluded for all tan(b) values and tan(b) >10 is excluded for all mA values provided h at 125 GeV is associated with given MSSM scenario • Excluded s × BR ranges from > 29 pb (>6.4 pb) at mf = 90 GeV to >7.4 pb (>7.2 pb) at mf =1000 GeV for ggF (b-associated) cases, respectively I.Tsukerman, RussianATLAS 2014

  17. Xhhbbgg exclusion at low and high masses Arxiv1406.5053 NEW • Search X mass range: 260-500 GeV • Non-resonant and resonant hh production in the bbgg final state is studied • SMhh-production is not observable in the available data: 0.04 events expected • However in some SM extensions (2HDM, composite models) it is higher • Signature: two high-pT isolated g, two energetic b-jets with M(gg) and Mbb close to mH = 125 GeV. BR(hbb) 0.57 • Backgrounds (continuum plus single h • production) are not big due to high M(gg) • resolution, giving in a total 1.5 events. • 2.4s excess is seen in the non-resonant • searches (5 events observed, they • correspond to steps in the exclusion plot). • Limits derived are juxtaposed with • expectation from a sample type I 2HDM • model with specific parameters not • excluded by current data 95% CL upper limit on sX×BR(Xhh) is between 0.8 pb and 3.5 pb; for non-resonant production it is set to 2.2 pb I.Tsukerman, RussianATLAS 2014

  18. Conclusion • ATLAS performed searches for BSM Higgs bosons in many decay channels using 7 TeV and 8 TeV datasets: • H± bosons in tnand cs channels, as well as in cascade H decays • High mass H0 decays to WWlnln, ZZ4l and gg • Hinvisible decay using Zll + H production • H/h/A decays into mm and tt in the MSSM model… • Hhh production with subsequent h decays to bb and gg • Although no deviations from the Standard Model were found, strict limits on production cross sections and branching ratios were set. • This limited parameter space of related theoretical models • ATLAS is continuing to search for BSM Higgs bosons in 7 and 8 TeV data using new channels with better analyses and plan to obtain much better results with • 13-14 TeV data expected starting from 2015 I.Tsukerman, RussianATLAS 2014

  19. Backup slides ATLAS publications about BSM Higgs boson searches Short information about theoretical models Additional material to main slides Papers in preparation I.Tsukerman, RussianATLAS 2014

  20. ATLAS publications related to BSM H searches Journal publications (final results) • Search for double Higgs production in the H→ggand H→bb decay channels, arxiv1406.5053 • Search for top quark decays t→ qH with H→γγ using the ATLAS detector, JHEP06 (2014) 112 • Search for Invisible Decays of a Higgs Boson Produced in Association with a Z Boson in ATLAS, PRL 112 (2014) 201802 • Search for a Multi-Higgs Boson Cascade in W+W- bbar events with the ATLAS detector in pp collisions at √s = 8 TeV, PRD89 (2014) 032002 • Search for a light charged Higgs boson in the decay channel H+ → csbar in ttbar events using pp collisions at √s = 7 TeV with the ATLAS detector, EPJ C73 (2013) 2465 • Search for charged Higgs bosons through the violation of lepton universality in ttbar events using pp collision data at √s = 7 TeV with the ATLAS experiment, JHEP03 (2013) 076 • Search for the neutral Higgs bosons of the Minimal Supersymmetric Standard Model in pp collisions at √s =7 TeV with the ATLAS detector, JHEP02 (2013) 095 • Search for a fermiophobic Higgs boson in the diphoton decay channel with the ATLAS detector, EPJC 72 (2012) 2157 I.Tsukerman, RussianATLAS 2014

  21. ATLAS publications related to BSM H searches ATLAS Conference Notes (preliminary results) • Limits on fiducial cross sections of additional Higgs states in the gamma gamma final state, ATLAS-CONF-2014-031 • Interpreting ATLAS Higgs coupling measurements within BSM models, ATLAS-CONF-2014-010 • Combined coupling measurements of the Higgs boson with the ATLAS detector using up to 25 fb-1 of proton-proton collision data, ATLAS-CONF-2014-009 • Search for charged Higgs bosons in the tau-nu final state with the ATLAS detector, ATLAS-CONF-2013-090 • FCNC top decays to H(yy)c for Spring 2013 Conferences, ATLAS-CONF-2013-081 • Search for a Heavy Higgs boson in the WW (lvlv) Channel, ATLAS-CONF-2013-067 • Search for Higgs bosons in 2HDM in the WW (lvlv) channel with the ATLAS detector, ATLAS-CONF-2013-067 ATLAS Public Notes (perspectives) • Beyond-the-Standard-Model Higgs boson searches at a High-Luminosity LHC with ATLAS, ATLAS-PHYS-PUB-2013-016 • Sensitivity to New Phenomena via Higgs Couplings with the ATLAS Detector at a High-Luminosity LHC, ATLAS-PHYS-PUB-2013-015 • Sensitivity of ATLAS at HL-LHC to flavour changing neutral currents intop quark decays t → cH, with H → γγ, ATLAS-PHYS-PUB-2013-012 I.Tsukerman, RussianATLAS 2014

  22. Two Higgs Doublet (2HDM) models Light h boson coupling to weak bosons coupling to up quarks coupling to down quarks coupling to leptons I.Tsukerman, RussianATLAS 2014

  23. MSSM and NMSSM models Minimal Super Symmetric Model (MSSM) • 5 Higgs bosons: 2 CP-even (heavy: H and light: h), one CP-odd neutral boson (A) and two charged bosons (H±). A is heavy In contrast to 2HDM models, here there are also SUSY particles Two parameters: mA and tan(b)=n2 / n1 Note. mh2 = mZ2 cos2 (2b) + d(mA,tan(b)) Next to Minimal Super Symmetric Model (NMSSM) • 7 Higgs bosons: two doublets and one singlet: h1, h2,h3; usually light a1 and a2pseudoscalarsand two charged bosons (H±). I.Tsukerman, RussianATLAS 2014

  24. Searches for H+ tn in tt events at 8 TeV ATLAS-CONF-2013-090 is t + ETmiss transverse mass Dft,missis azimuthal angle between hadronic decay product of t and direction of missing transverse momentum No deviation from the SM is seen No deviation from the SM is seen I.Tsukerman, RussianATLAS 2014

  25. MSSM: production and decay modes of A • Main production modes are gluon-gluon fusion and associated bbA • Enhancement of bbA mode is possible at large tan(b) • Main decay mode is Abb, but it is not practical due to large background • Attmode is reasonable in terms of sensitivity • Ammmode is rare, but the signature is very clean I.Tsukerman, RussianATLAS 2014

  26. MSSM ftt searches: details ATLAS-CONF-2014-049 NEW Final states of the best exclusion: leplep for 90 GeV<mA<200 GeV hadhad for 200 GeV<mA<300 GeV hadhad for 300 GeV<mA<1000 GeV Data/MC:OK I.Tsukerman, RussianATLAS 2014

  27. Higgs boson and dark matter From S. Rosati presentation at ICHEP 2014 (PLB 709 (2012) 65) I.Tsukerman, RussianATLAS 2014

  28. Papers in preparation for BSM Higgs searches A/Htt H+tn AZh HJ/y g aammtt gga1 mm I.Tsukerman, RussianATLAS 2014

  29. Papers in preparation H+Wa1 HINV Hhh 4b H multi g H+tb HZZ HWW bH/Abb I.Tsukerman, RussianATLAS2014 1/4/2020

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