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Prospects for VV scattering : latest news

Prospects for VV scattering : latest news. S.Bolognesi (Johns Hopkins University) on behalf of CMS and ATLAS. Implications of LHC results for TeV -Scale physics – CERN, March 2012 . VV scattering: unitarity violation. VV -> VV. V. V. V. V. V.

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Prospects for VV scattering : latest news

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  1. Prospects for VV scattering: latest news S.Bolognesi (Johns Hopkins University) on behalf of CMS and ATLAS Implications of LHC results for TeV-Scale physics – CERN, March 2012

  2. VV scattering: unitarity violation VV -> VV V V V V V W,Z mass (-> longitudinal degrees of freedom) arise from the Higgs mechanism: without Higgs, W+LW-L->W+LW-L would break unitarity S channel T channel QGC Same behavior for all VV amplitudes VV scattering is the smoking gun of the EWSB ! Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 2

  3. VV scattering as probe for EWSB • VV scattering spectrum s(VV->VV) vs M(VV) is the fundamental probe to test nature of Higgs boson or to find alternative EWSB mechanism SM No-Higgs LSB>1TeV LSB<1TeV Unitarity violation SB sector strongly coupled SB sector weakly coupled other scenarios possible: eg, strongly interacting light Higgs Personal adaptation from “Boson Boson scattering analysis”by A.Ballestrero (INFN Torino) talk at First LHC to Terascale Workshop (Sept 2011): Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 3

  4. Experimental signature Typical signature: forward-backward “spectator” jets with very high energy ggH + 2jets ggH + 2jets JHEP 0704 (2007) 052 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 4

  5. VV scattering in real life (1) • In no Higgs case: increasing of xsec at high VV is suppressed by • PDF • offshell bosons • unpolarized bosons → smalldifference btw SM and violation of unitarity (no Higgs) W±W± Personal adaptation from “Boson Boson scattering analysis”by A.Ballestrero (INFN Torino) talk at First LHC to Terascale Workshop (Sept 2011): W±W± SILH PHANTOM MC PHANTOM MC → with proper cut (egDh jets) can be enhanced -> selection of the longitudinal W Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 5

  6. Longitudinal vs Transversal mH 500 GeV noHiggs (unitarity violation) • Angular analysis can boost LL-TT separation (new!): partonic study in the center of mass of W WW tail (TT): neutrino WW tail (TT): lepton Higgs peak (LL): neutrino Higgs peak (LL): lepton Transverse distribution Longitudinal distribution Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 6

  7. VV scattering in real life (2) irreducible background (aEW6) signal 2 ... JHEP 0603 (2006) 093 hep-ph/0505225v1 WW signal with “a posteriori” cuts WW approximated without interference Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 7

  8. Outline • Review of theoretical tools • Experimental status: no new results but similar issues under study in other analyses • (short!) historical review and comparison with recent results for similar final states: graviton and higgs searches at high mass • fully leptonic • semi-leptonic: • V+jets control • jet merging for high pt V->jj • tag jets and central jet veto • VBF Higgs search • Z VBF analysis • first (QCD) measurements of FWD jets and jet veto Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 8

  9. Theoretical tools Variouscomplementary MC • PHANTOM qq->6f @ aEW6 + aEW4 × aS2 hep-ph/0701105v2 LO, full description of irreducible background with correct interference • VBF@NLO QCD+EW NLO for VBF Higgs production QCD NLO for VV scattering ratio btw scales • HAWK QCD+EW NLO for VBF+HiggsStralung Higgs production • POWHEG QCD NLO for VBF+HiggsStralung + PS matching • LO ME MC + PS (Madgraph, Pythia, Herwig) Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 9

  10. Any news from experiments? HIG-12-008 No dedicated analysis yet (low lumi) -> but arriving to VV scattering in 2 ways higher mass BSM search for VV resonance @ 1 TeV (DY production) ->studying same final states as VV scattering higher sensitivity VBF dedicated search -> characterization of tag jets signature Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 10

  11. Graviton->ZZ search • Search for G→ZZ: same features discussed for high mass Higgs ZZ→llnn ZZ→lljj: large V+jets MET control V+jets ZZ→4l low statistics Phys. Rev. D83, 112008 (2011) CMS is working on ZZ→4l ZZ->2l2j (angular analysis) ZZ→lljj hep-ex arXiv:1203.0718 ZZ->2l 1j (jet merging) Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 11

  12. VV scattering: fully leptonic CMS AN 2007-005 Only background VV+jets, very low xsec Number of events for 20 fb-1 (fully MC based, no systematics, 14 TeV) N sign. N back. CMS ZZ->4e, 4m ATLAS ZZ->2l2n N sign. N back. CERN-OPEN-2008-020 6.4 3.0 500 GeV 2.2 1.9 500 GeV >1 TeV 0.1 0.2 N sign. N back. ATLAS ZW->lllv 500 GeV 5 8 CMS ZW->mmmv N sign. N back. 0.4 1.4 1.1 TeV >1 TeV 0.9 0.8 Latest results: B~ 6 S~ 10 Example: ggF Higgs 300 GeV hep-ex arXiv:1202.1415 B~ 80 S~ 200 • resom(ll) as expected • improved reco-id efficiencies 14 TeV, 30 fb-1 (egele ID: TDR time 85-90% -> today 95%) CERN-OPEN-2008-020 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 12

  13. VV scattering:semileptonic CMS AN 2007-005 Semileptonic is most promising: reasonable signal yield (fully MC based, no systematics, 14 TeV) Number of events for 20 fb-1 N sign. N back. ATLAS N sign. N back. CMS N sign. N back. CMS CERN-OPEN-2008-020 500 GeV 6.2 16 337 20759 500 GeV 62 3415 500 GeV ZV -> lljj 13 800 GeV 17 WV -> lnjj 45 3281 >1 TeV 5 4.8 1.1 TeV 348 >1 TeV 9.2 HIG-11-027 Z->jj mass for H->ZZ->2l2q For recent inclusive Higgs search: • more sophisticated analysis developed • (btag categories, angular analyses, • m(jj)=mZkinematic fit) • data driven background Improved JES: mjjreso from 20-25% to 10-15% ! Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 13

  14. V+jets PRL 106,171801 (2011) • Control region (eg, Z→jj sidebands) has very low stat for M(lljj)~1 TeV • Improving theoretical tools(Blackhat, Madgraph, …) • test them where we have statistics • rely on them to extrapolate at higher energy -> Angular analysis to boost sensitivity -> angular correlations in Z+jets!! Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 14

  15. V+jets measurements • QCD measurement (jet pT>20-30 GeV): hep-ex arXiv:1201.1276 syst. dominated by jet scale + PileUpremoval, but good status at LHC -> LHC: very high statistics even at high multiplicity -> differential distributions →Tevatron: angularvariables D0 novel measurement: angular correlations have much lower systematics Implication of LHC results for TeV-Scale physics 15

  16. Jet merging AkT 0.6 • Issue under study for EXO searches • (boosted top, gravitons) www.pha.jhu.edu/groups/particle-theory/seminars/talks/F11/talk.khron.pdf WW scattering (1.1 TeV resonance) @14 TeV approx DR 0.8 (CA) → MX>600 GeV DR 0.5 (Akt) → MX>900 GeV • Handles to distinguish V->jwrtto jets from QCD (Z+jets): • jet radiation (sub-jet structure) -> pruning Z+jets • jet mass X->ZZ->2l2q signal Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 16

  17. Any news from experiments? HIG-12-008 No dedicated analysis yet (low lumi) -> but arriving to VV scattering in 2 ways higher mass BSM search for VV resonance @ 1 TeV (DY production) ->studying same final states as VV scattering higher sensitivity VBF dedicated search -> characterization of tag jets signature Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 17

  18. Fermiophobic-like • WHY? Ex of (light) composite higgs: LCH at LHC by J.R. Espinoza First LHC to Terascale Workshop (Sept 2011) • “State of the art” • gg at low mass, • WW at high mass • NO dedicated VBF analysis yet for ZZ !! HIG-12-008 HIG-12-008 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 18

  19. First look at tag jets FWD jet • Starting to face issues related with tag jets topology and jet vetoing -> very relevant for VV scattering: no color flow -> jet veto FWD jet • control of VV background in jet-multiplicity bins -> theoretical systematics (no control regions for ZZ, WW at high mass) • Z prodution in VBF: a candle for jet tagging and jet veto efficiency? -> (after feasibility) real data analysis ongoing • MC tools to describe FWD jets and gap events -> related with description of UE, MPI and QCD at wide angle -> many useful measurements can be done NOW to constraint FWD jets modeling -> TO BE REVIEWED THIS YEAR WITH MUCH HIGHER PU Implication of LHC results for TeV-Scale physics 19 S.Bolognesi (JHU)

  20. WW backgr. in jet multiplicity bins • Exclusive computation have huge errors due to higher pertubative orders ex for H signal: different treatments of the uncontrolled higher-order O(α3s) terms i.e., different NNLO expansions • Inclusive xsec (σ≥Njets), as source of perturbative uncertainties Higgs xsec WG: hep-ex arXiv:1201.3084 -> uncert. on σN = σ≥N − σ≥N+1 with error propagation Uncertainty from MC@NLO scale variation (2nd jet from PS) + ALPGEN comparison Acceptance evaluated in each exclusive jet bin (uncert~5%) + PDF uncertainty (~2%) Implication of LHC results for TeV-Scale physics 20 S.Bolognesi (JHU)

  21. Z in VBF as a candle? • VBF Z production as reference: feasibility study at parton-level @ 10 TeV hep-ex arXiv:1001.4357 Z+qq (4 pb) : signal (~5%) isolated “a posteriori” with partonic cuts -> 2700 events @ 15 fb-1 irreducible background -> 45% eff for VBF-specific cuts -> 23% tighter cuts against Z+jetsQCD (2700 pb) S/B improved of a factor 100: 600/78k events @ 15 fb-1 (S/sqrt(B)~ 2) • Observation feasible but to use as reference need high lumi and to know Z+jets with high precision • Central jet veto suppress only 10% of Z+jets(~useless!) Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 21

  22. Jet veto • 3rd jet not well modeled by PS, • central veto De btw Pythia and Herwig ~ 40% ->POWHEG NLO: remaining uncertainty ~% hep-ex arXiv:1107.1641 Higgs xsec WG: hep-ex arXiv:1201.3084 • Check with dijet events + rapidity gap (in low PU) (at large pTjet/pTveto or Dy -> fixed order fails) • NP effects<2% (pTveto > LQCD) • HEJ all-order resummation for wide-angle emissions of similar pT -> fails for pT jet>>pTveto • POWHEG+Pythiagood agreement with data -> differences btw Herwig and Pythia • Similar study in ttbar events ! hep-ex arXiv:1203.5015 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 22

  23. FWD jets modeling • energy lost from jets due to hadronisation • Non-perturbative effects: • energy added to jets from UE • FWD jet spectrum (|h|3.2-4.7) with low PU events central + forward jet hep-ex arXiv:1202.0704 NLO+NP and Powheg+Pythia catch the dependence, not the xsec Herwig does a better job than pythia Pythia Z2 tuned to LHC UE • useful also to commission our detector -> especially in view of PU Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 23

  24. Summary • Start studying VV-scattering related issues in different frameworks: • high mass general X->VV search (Higgs SM or BSM, eg graviton) exercising the reconstruction and identification of same final states improve V+jetscontrol studying jet merging • tag jets and jet veto understanding VV in jet multiplicites testing FWD jets modeling and jet vetoing in data Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 24

  25. BACK-UP:prospects for VV scattering: latest news S.Bolognesi (Johns Hopkins University) on behalf of CMS and ATLAS Implications of LHC results for TeV-Scale physics – CERN, March 2012

  26. PDF+as Di-boson background qq qq→ZZ NLO + gg→ZZ scale qq

  27. Signal: jet counting • if background depends on Njets • Analysis in exclusive jet bins (ex, WW+0,1,2 jets) • for VBF → theoretical uncert in jet bins to be combined with correlations different treatments of the uncontrolled higher-order O(α3s) terms • varying renormalization and factorization scales in the fixed-order predictions for each exclusive jet cross section σN i.e., different NNLO expansions (results as 100% correlated) • inclusive xsec (σ≥Njets), as source of perturbative uncertainties σN = σ≥N − σ≥N+1 with error propagation LHC To Terascale Physics WS 41 S.Bolognesi (Johns Hopkins University)

  28. WW same sign Final state with largest effects from unitarity violation 10 TeV 60 fb-1 Eur.Phys.J.C71:1514,2011. 10 TeV 60 fb-1 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 15

  29. Higgs-like resonance in VBF • RE-DO all the analyses in VBF mode • Today only WW→lnln. Expectations for next year: summer2011 • lumi> 10 fb-1 VBF yields in 2012 ~ 0.5 gg yields of 2011 summer results, • s(vbf) ~ 0.1×s(gg) • 0.5 effic. VBF cuts with much less background: HIG-11-011 • ZZ→4l will be still limited by statistics • WW→lnln will improve S/B (signal/10, WW*as2) • semileptonic final states will havereasonable signal yields + much lower backgroundthan inclusive analysis Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 24

  30. Looking forward to VV scattering Same issues (as Higgs search and) as expected in VV scattering search • fully leptonics: much lower stat, much cleaner 14 TeV, 60 fb-1 qqmmmm uncertainty on VV+2jproduction • semileptonic: larger yields, huge background V+jetscontrol high VV mass -> boosted V -> jet merging • first look at fully hadronicfinal state ongoing SUSY-like discriminators (eg, Razor) 14 TeV, 60 fb-1 qqqqmm Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 3

  31. Historical references • CMS model independent-approach Higgs resonance @ 500 GeV most conservative scenario: SM with no Higgs (mH->inf) CMS AN 2007-005 • ATLAS ChiralLagrangian withPade’ unitarization • -> higher xsec with resonance peak CERN-OPEN-2008-020 14 TeV !!!! xsec ~ 100 fb Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 13

  32. ATLAS-CONF-2012-018 Comparing to recent results 14 TeV, 60 fb-1 B~ 2000 S~ 300 B~ 20 S~ 2 VBF H->WW->lnjj (electron channel) 14 TeV, 60 fb-1 (muon channel) HIG-11-027 H->ZZ->lljj B~ 5000 S~ 80 VBF 14 TeVvs recent inclusive results ggF (2btag) B~ 20 S~ 8 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 14

  33. Jet pruning • Remove all parts of the jet which aresoft and wide angle • QCD jets mass substantially decreased -> lower backgrounds Boosted objects mass reconstruction improved X->ZZ->2l2q signal Z+jets • RS Graviton • MG 1500 GeV • CA 0.8 Implication of LHC results for TeV-Scale physics S.Bolognesi (JHU) 18

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