Higgs + 2 Jet Production: Loops and CP properties

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1 iggs + 2 Jet Production: Loops and CP properties Gunnar Klämke Institut für Theoretische Physik, Universität Karlsruhe SFB Meeting Aachen, February 21-23, 2007 iggs production at the LC /A + 2 jets production in gluon fusion W W as a signal channel Jet azimuthal angle correlations Probing CP properties Summary Gunnar Klämke, SFB Meeting Aachen, February 21-23,

2 iggs Production Channels at the LC gg (NNLO) σ(pp + X) [pb] s = 14 TeV NLO / NNLO t t t _ ' W V V gg/ _ tt _ (NLO) _ Z MRST W, Z _ t t [Krämer ( 02)] M [GeV] Gunnar Klämke, SFB Meeting Aachen, February 21-23,

3 Vector Boson Fusion p V W W τ m > 120 GeV p V τ + γ m < 140 GeV W m < 150 GeV γ [Eboli, agiwara, Kauer, Plehn, Rainwater, Zeppenfeld... ] Most measurements can be performed at the LC with statistical accuracies on the measured cross sections times decay branching ratios, σ BR, of order 10% (sometimes even better). Gunnar Klämke, SFB Meeting Aachen, February 21-23,

4 ow to distinguish gluon fusion and VBF? W ±, Z g vs. t W ±, Z g vector boson fusion gluon fusion Double real corrections to gg can fake VBF = we need to investigate the phenomenology of these two processes and understand the differences that can be exploited to distinguish between gluon fusion and VBF = derive cuts to be applied to enhance VBF with respect to gluon fusion. Measure W W and ZZ coupling = derive cuts to be applied to enhance gluon fusion with respect to VBF. Measure effective gg coupling or tt coupling Gunnar Klämke, SFB Meeting Aachen, February 21-23,

5 VBF signature p + µ J 2 J 1 ϕ J 1 θ 2 θ 1 p µ + ϕ ϕ jj e - J 2 e - η Characteristics: energetic jets in the forward and backward directions (p T > 20 GeV) large rapidity separation and large invariant mass of the two tagging jets iggs decay products between tagging jets Little gluon radiation in the central-rapidity region, due to colorless W/Z exchange (central jet veto: no extra jets with p T > 20 GeV and η < 2.5) Gunnar Klämke, SFB Meeting Aachen, February 21-23,

6 Diagrams for gg fusion with finite m t effects A, A, A, (a) (b) A, A, (c) A, plus crossed processes. In total 61 independent diagrams. [DelDuca, Kilgore, Oleari, Schmidt, Zeppenfeld (2001)] Implementation of pseudoscalar iggs (pp AjjX), including top and bottom loops + interference (Michael Kubocz, Diploma Thesis) Gunnar Klämke, SFB Meeting Aachen, February 21-23,

7 Gluon Fusion as a signal channel eavy uark loop induces effective gg vertex (m Q limit): CP even : CP odd : i m Q v L eff = α s 12πv Ga µν Gµν,a m Q v γ 5 L eff = α s 8πv A Ga µν G µν,a = α s 16πv A Ga µν Ga αβ εµναβ Azimuthal angle between tagging jets probes difference Use gluon fusion induced Φjj signal to probe structure of gg vertex Find cuts to enhance gluon fusion over VBF and other backgrounds paper ready for submission (KA-TP ) Gunnar Klämke, SFB Meeting Aachen, February 21-23,

8 Gluon fusion signal and backgrounds Signal channel (LO): pp jj in gluon fusion with W + W l + l ν ν, (l = e, µ) m = 160 GeV dominant backgrounds: W + W -production via VBF (including iggs-channel): pp W + W jj top-paar production: pp t t, t tj, t tjj [N. Kauer] QCD induced W + W -production: pp W + W jj applied inclusive cuts (minimal cuts) : 2 tagging-jets p T j > 30 GeV, η j < identified leptons p T l > 10 GeV, η l < 2.5 separation of jets and leptons η jj > 1.0, R jl > 0.7 process σ [fb] GF pp + jj VBF pp W + W + jj 75.2 pp t t 6832 pp t t + j 9518 pp t t + jj 1676 QCD pp W + W + jj 363 Gunnar Klämke, SFB Meeting Aachen, February 21-23,

9 Characteristic distributions Separation of VBF jj signal from QCD background is much easier than separation of gluon fusion jj signal jj 1/σ dσ/d η tagging jet rapidity separation signal VBF tt+jets QCD-WW [1/GeV] 1/σ dσ/dm jj dijet invariant mass signal VBF tt+jets QCD-WW η jj m jj [GeV] Gunnar Klämke, SFB Meeting Aachen, February 21-23,

10 Selection b-tagging for reduction of top-backgrounds. (CMS Note 06/014) (η, p T ) - dependent tagging-efficiencies (60% - 75%) with10% mistagging-probability selection cuts: p T l > 30 GeV, M ll < 75 GeV, M ll < 0.44 M W W T, R ll < 1.1, M W W T < 170 GeV, p T > 30 GeV M W W T = (E T + E Tll ) 2 ( p Tll + p T ) 2 1/σ dσ/d R ll [1/GeV] WW 1/σ dσ/dm T Signal VBF t t+jets QCD-WW R ll lepton-lepton R-separation WW [GeV] m T transverse mass of dilepton system Gunnar Klämke, SFB Meeting Aachen, February 21-23,

11 Results process σ [fb] events/30 fb 1 GF pp + jj VBF pp W + W + jj pp t t pp t t + j pp t t + jj QCD pp W + W + jj Σ backgrounds S/ B 16.2 for 30 fb 1 Gunnar Klämke, SFB Meeting Aachen, February 21-23,

12 General tensor structure of the V V coupling SM iggs coupling to vector bosons: L SM V µ V µ (V = Z, W) Tensorstructure: g µν γ, Z, W, g 1-loop induced CP-even coupling: L eff V µν V µν (V = Z, W, g) Tensorstructure: 1 2 g µν ν 1 µ 2 1-loop induced CP-odd coupling: L eff V µν Ṽ µν (V = Z, W, g) Tensorstructure: ɛ µνρσ 1ρ 2σ γ, Z, W, g 2, ν 1, µ p General VV vertex with scalar formfactors a 1, a 2, a 3 : T µν ( 1, 2 ) = a 1 g µν + a {z } 2 [ 1 2 g µν µ {z 2 ν 1 } ] SM (V BF ) CP even (GF ) + a 3 ɛ µνρσ 1ρ 2σ {z } CP odd (GF ) In VBF: a 1 present for SM iggs; a 2, a 3 for anomalous W W /ZZ coupling. In gluon fusion: only a 2, a 3 present. Must distinguish a 1, a 2, a 3 experimentally. Gunnar Klämke, SFB Meeting Aachen, February 21-23,

13 Azimuthal angle distribution and iggs CP properties Kinematics of jj event: Define azimuthal angle between jet momenta j + and j via ε µνρσ b µ + jν + bρ jσ = 2p T,+p T, sin(φ + φ ) = 2 p T,+ p T, sin φ jj φ jj becomes signed φ jj is a parity odd observable φ jj is invariant under interchange of beam directions (b +, j + ) (b, j ) φ jj distribution allows to extract the complete information about the tensor structure of the V V coupling. [Figy, ankele, Klämke, Zeppenfeld (hep-ph/ )] Gunnar Klämke, SFB Meeting Aachen, February 21-23,

14 Signals for CP violation in the iggs Sector 1/σ dσ/d Φ jj pp jj m = 160 GeV CP-even CP-odd CP-mixed jj in gluon fusion mixed CP case: a 2 = a 3 pure CP-even case: a 2 only pure CP odd case: a 3 only Φ jj Position of minimum of φ jj distribution measures relative size of CP-even and CP-odd couplings. For = Minimum at α and π α a 2 = d sin α, a 3 = d cos α, Gunnar Klämke, SFB Meeting Aachen, February 21-23,

15 Φ jj -Distribution in the presence of backgrounds Fit to Φ jj -distribution with function f( Φ) = N(1 + A cos[2( Φ Φ max )] B cos( Φ)) events events Signal VBF t t+jets QCD-WW Φ jj Φ jj L = 300 fb 1 ( η jj > 3.0) CP-even CP-odd A = ± A = ± Φ max = 5.8 ± 15.3 Φ max = 93.7 ± 5.1 fit of the background only : A = ± and Φ max = 64 ± 25 ( mean values of 10 independent fits of data for L = 30 fb 1 ) Gunnar Klämke, SFB Meeting Aachen, February 21-23,

16 Φ jj -Distribution: CP violating case events Φ jj CP-mixture: eual CP-even and CP-odd contributions (a 2 = a 3 ) A = ± Φ max = 45.6 ± 7.3 Gunnar Klämke, SFB Meeting Aachen, February 21-23,

17 Summary Gluon fusion is a copious source of jj events at the LC Full one-loop calculations are available for uark-loop induced jj and Ajj production, including CP-even CP-odd interference and finite uark mass effects For m = 160 GeV and dominant decay W W the gluon fusion induced signal at the LC is visible above backgrounds. The CP properties of the gg vertex can be obtained from jet-angular correlations A modified definition of the azimuthal angle resolves ambiguities in CP-mixtures Gunnar Klämke, SFB Meeting Aachen, February 21-23,

18 Backup slides Gunnar Klämke, SFB Meeting Aachen, February 21-23,

19 Total cross section for SM iggs & m t limit Total cross section: Large top mass limit ok provided m < m t Transverse momentum: Large top mass limit ok provided p T,j < m t (inclusive cuts: p T j > 20 GeV, η j < 5, R jj > 0.6 ) Gunnar Klämke, SFB Meeting Aachen, February 21-23,

20 Results for pseudoscalar iggs AQQ vertices given by m b v γ 5 tan β and m t v γ 5 1 tan β Interference of top and bottom loops Can simulate CP violation in the iggs sector: a + ibγ 5 coupling to top and bottom Inclusive cuts Inclusive cuts σ [pb] 2 10 tanβ=1, m =175 GeV t tanβ=50, m =4.4 GeV b tanβ=7, t+b 10 σ [pb] tan β = 1, IC 0 A, m = 175 GeV t m 0 SM, m t = 175 GeV m A [GeV] m iggs [GeV] top & bottom loop for different tan β CP-odd vs. CP-even iggs Gunnar Klämke, SFB Meeting Aachen, February 21-23,