Heavy Electroweak Resonances at the LHC

Transcription

1 Heavy Electroweak Resonances at the LHC (arxiv: Ongoing work) Brookhaven National Lab with Agashe, Davoudiasl, Han, Huang, Perez, Si, Soni LHC-08, KITP, Santa Barbara Apr. 2008

2 Motivation SM Hierarchy Problem: M Pl New dynamics? M EW Extra dimensions (Warped, Flat) Supersymmetry Strong dynamics Little Higgs AdS/CFT correspondence

3 Talk Outline Focus on heavy EW spin-1 resonances Warped (RS) model SU(3) QCD SU(2) L SU(2) R U(1) X bulk gauge group Heavy EW gauge bosons : 3 neutral (Z ) & 2 charged (W ± ) Precision electroweak observables require M Z, M W ± 2 TeV 1 Makes discovery challenging at the LHC What are general issues at the LHC?

4 Talk Outline Focus on heavy EW spin-1 resonances Warped (RS) model SU(3) QCD SU(2) L SU(2) R U(1) X bulk gauge group Heavy EW gauge bosons : 3 neutral (Z ) & 2 charged (W ± ) Precision electroweak observables require M Z, M W ± 2 TeV 1 Makes discovery challenging at the LHC What are general issues at the LHC? Not discussed here: KK Gluon (SU(3) QCD ) at LHC [Agashe et al, 06] [Lillie et al, 07] KK Graviton at LHC [Agashe et al, 07] [Fitzpatrick et al, 07]

5 Warped Model 5D Warped Space [Randall, Sundrum, 99] ds 2 = e 2k y (η µνdx µ dx ν ) + dy 2 Z 2 Orbifold - Planck (UV) Brane TeV (IR) Brane R : radius of Ex. Dim. k : curvature Hierarchy prob soln: 0 y πr y=0 UV TeV Brane Higgs : M EW ke kπr : Choose kπr 34 y=πr IR Bulk fields AdS/CFT Bulk Fermions explain flavor (FCNC s safe)

6 Constraints Precision Electroweak Constraints (S, T, Zb b) Bulk gauge symm - SU(2) L U(1) (SM ψ, H on TeV Brane) T parameter - log M Pl M EW enhanced [Csaki, Erlich, Terning - 02] S parameter - log enhanced Bulk gauge symm - SU(2) R Custodial Symm (AdS/CFT) [Agashe, Delgado, May, Sundrum - 03] T parameter - Protected 1 S parameter - log enhanced (with additional for bulk fermions) kπr Zb b shifted 3rd gen quarks (2,2) [Agashe, Contino, DaRold, Pomarol - 06] Zb b coupling - Protected Precision EW constraints M Z 2 3 TeV [Carena, Ponton, Santiago, Wagner - 06,07]

7 Gauge Sector Bulk Gauge group : SU(2) L SU(2) R U(1) X Three neutral gauge bosons: (W 3 L, W 3 R, X ) Two charged gauge bosons: (W ± L, W ± R )

8 Gauge Sector Bulk Gauge group : SU(2) L SU(2) R U(1) X Three neutral gauge bosons: (W 3 L, W 3 R, X ) Two charged gauge bosons: (W ± L, W ± R ) SU(2) R U(1) X U(1) Y : (W 3 L, W 3 R, X ) (W 3 L, B, Z X ) 1 Z X (g g 2 R W 3 x +gr 2 R g X X ) (, +) ; W ± R (, +) 1 B (g g 2 X W 3 x +gr 2 R + g RX ) (+, +) ; W ± L (+, +) Symm breaking by BC: Z X (, +) means Z X y=0 = 0 ; y Z X y=πr = 0

9 Gauge Sector Bulk Gauge group : SU(2) L SU(2) R U(1) X Three neutral gauge bosons: (W 3 L, W 3 R, X ) Two charged gauge bosons: (W ± L, W ± R ) SU(2) R U(1) X U(1) Y : (W 3 L, W 3 R, X ) (W 3 L, B, Z X ) 1 Z X (g g 2 R W 3 x +gr 2 R g X X ) (, +) ; W ± R (, +) 1 B (g g 2 X W 3 x +gr 2 R + g RX ) (+, +) ; W ± L (+, +) Symm breaking by BC: Z X (, +) means Z X y=0 = 0 ; y Z X y=πr = 0 SU(2) L U(1) Y U(1) EM : (W 3 L, B, Z X ) (A, Z, Z X ) By TeV brane Higgs

10 KK States Kaluza-Klein (KK) expansion: A(x, y) = 0 f n(y) A (n) (x) A (n) KK tower with mass m n. Equivalent 4D theory Gauge Boson Zero modes: A (0), Z (0) ; W (0) L First KK modes: A (1), Z (1), Z (1) X Z ; W (1) L, W (1) R EWSB mixes : Z (0) Z (1) ; Z (0) Z (1) X ; Z (1) Z (1) X W (0) L W (1) L ; W (0) L W (1) R ; W (1) L W (1) R Mass eigenstates : Zero modes: A, Z ; W ± First KK modes: A 1, Z 1, Z X1 Z ; W L1, W R1 W ±

11 Representations (Custodial protection for Zb b) Fermions ( tl ζ Q L = (2, 2) = L b L T L t R : (1, 1) OR (1, 3) b R : (1, 1) OR (1, 3) Higgs Σ = (2, 2) ) [Agashe, Contino, DaRold, Pomarol - 06] For these Reps Zb b coupling - Protected [Agashe, Contino, DaRold, Pomarol - 06] Precision EW constraints M Z 2 3 TeV [Carena, Ponton, Santiago, Wagner - 06,07]

12 Wave functions Bulk field EOM gives profiles in extra-dimension Fermion bulk mass (c parameter) controls localization h f 1 χ t R f 0 q 3 Compute overlap integral of f (y) g(y) to get 4D couplings I +, = [dy]gψ 2 f (++),( +) A (+, +) ; Z (+, +) ; Z X (, +)

13 Z ANALYSIS

14 Z couplings Z overlap with Higgs ξ Z overlap with fermions: Compared to SM Define: ξ kπr 5 Q 3 L t R other fermions I + 1 ξ 1 ξ I 1 ξ 0 Z couplings to h enhanced (also V L - Equivalence Theorem!) Z couplings to t R enhanced Z couplings to χ suppressed ψ L,R γ µ[ ( eqia 1 µ + g Z T 3 L sw 2 ) T Q IZ1 µ + ( g Z T 3 R s 2 ) ] T Y IZX 1 µ ψ L,R

15 EWSB induced Z W + W coupling Z (1) V (0) V (0) is zero by orthogonality but induced after EWSB W + = Z Z (1) Z Z (1) W + W + W (1)+ Z (1) W (1) W + W W W W Even though ξ ( v M KK ) 2 suppressed can be overcome by ( M KK m Z ) 2 (from long. pol. vectors) Hence important to keep

16 Z decays [Agashe, Davoudiasl, SG, Han, Huang, Perez, Si, Soni - arxiv: [hep-ph]] Z W + Z W Z h t, b, l Z t, b, l + Γ(A 1 W L W L ) = e2 κ 2 192π M 5 Z m 4 W Γ( Z 1, Z X 1 W L W L ) = g 2 L c2 W κ2 192π M 5 Z m 4 W ; κ kπr c ( ; κ kπr c ( Γ( Z 1, Z X 1 Z L h) = g 2 Z κ2 192π M Z ; κ kπr c, Γ(Z f f ) = (e2, g 2 Z ) 12π ( κ 2 V + κ 2 ) A MZ. m W M W ± 1 ) 2, m Z (M Z1, M ZX 1 ) ) 2,

17 Total Widths M Z = 2TeV A 1 Z 1 Z X 1 Γ (GeV)

18 Z Branching Ratios

19 Z Branching Ratios (Contd.)

20 Z production at the LHC q q Z

21 LHC Channels pp Z W + W Fully leptonic : W lν ; W lν Semi leptonic : W lν ; W (j j) pp Z Z h m h = 120GeV : Z l + l ; h b b m h = 150GeV : Z (j j) ; h W + W (j j) lν pp Z l + l Clean but needs high luminosity pp Z t t, b b [Djouadi, Moreau, Singh - 07] KK gluon pollution

22 pp Z W + W l ν l ν 2 ν s cannot reconstruct event Diff c. s. [pb/gev] e-04 1e-05 1e-06 1e-07 1e-08 Di-lepton invariant mass 2TeV Z 3TeV Z SM WW SM τ τ Diff c. s. [pb/gev] e-04 1e-05 1e-06 1e-07 1e-08 Transverse mass 2TeV Z 3TeV Z SM WW SM τ τ 1e M ll 1e M T M eff p Tl1 + p Tl2 + /p T M TWW 2 pt 2 ll + Mll 2 L needed: 100 fb 1 (2 TeV) ; 1000 fb 1 (3 TeV)

23 pp Z W + W l ν j j jj opening angle 2TeV Z θ jj Jet-mass Z no Smr SM no Smr Z w/ Smr SM w/ Smr M jet (GeV) j j Collimation implies forming m W nontrivial : use jet-mass In our study: Jet-mass after Parton shower in Pythia [Thanks to Frank Paige for discussions] To account for (HCal) expt. uncert. Smearing by δe = 80%/ E ; δη, δφ = 0.05 Tracker + ECal (2 cores?) have better resolutions [F. Paige; M. Strassler] L needed: 100 fb 1 (2 TeV) ; 1000 fb 1 (3 TeV)

24 pp Z Z h l + l b b (m h = 120 GeV) Diff c.s. [pb/gev] e-04 1e-05 1e-06 1e-07 Z h invariant mass 2TeV Z 3TeV Z SM Z b SM Z b B Diff c.s. [pb/gev] e-04 1e-05 1e-06 1e-07 1e-08 1e-09 Z p T 2TeV Z 3TeV Z SM Z b SM Z b B 1e M Zh (GeV) 1e p TZ (GeV) How well can we tag high p T b s? For ɛ b = 0.4, expect R j 20 50; R c = 5 Two b s close : R bb 0.16 L needed: 200 fb 1 (2 TeV) ; 1000 fb 1 (3 TeV)

25 pp Z Z h : Z j j ; h W + W j j l ν (m h = 150 GeV) Diff c.s. [pb/gev] 1e-04 1e-05 1e-06 1e-07 1e-08 M inv and M T 2TeV Z M inv 2TeV Z M T 3TeV Z M inv 3TeV Z M T M TZh qp 2TZ + m 2Z + q p 2 T h + m 2 h 1e-09 1e M inv, M T (GeV) M Z = 2 TeV m h = 150 GeV Basic p T, η cos θ M T M jet # Evts S/B S/ B Z hz l /E T (jj) (jj) SM W j j SM W Z j SM W W j M Z = 3 TeV m h = 150 GeV Z hz l /E T (jj) (jj) SM W j j # events above is for 2 TeV : 100 fb 1 3 TeV : 300 fb 1

26 pp Z l + l M Z = 2 TeV Basic p T l M ll # Evts S/B S/ B Signal SM ll SM WW # events above is for 2 TeV : 1000 fb 1 Experimentally clean, but needs a LOT of luminosity

27 W ± ANALYSIS (ongoing)

28 W ± width W ~ L 1 + (i) W ~ R 1 + (i) W ~ L 1 + (ii) W ~ R 1 + (ii) W + X X Width [GeV] M W [GeV]

29 W ± BR BR(W ~ L 1 + X X) BR(W ~ R 1 + X X) 1 t L b - W + h T L b - χ L t - L Z W + u d - ν e e + 1 T L b - χ L t - L Z W + t L b - W + h u d - ν e e M W [GeV] M W [GeV]

30 W ± t b lνb b Signal c.s. 1fb Bkgnd is single top + QCD W b b... AND... t t : hadronically decaying top can fake a b b-jet Event Jet Cluster (diff) t-jet Event Jet Cluster (diff) pt i /pttot b Evt 2 pt i /pttot t Evt deta dphi deta dphi b-jet Event Jet Cluster (diff) t-jet Event Jet Cluster (diff) pt i /pttot b Evt 4 pt i /pttot t Evt deta dphi deta dphi

31 W ± t b lνb b Jet Mass : ConSiz=0.4, VetoFrac= Jet Mass (GeV) b-jet t-jet Jet Mass : ConSiz=1.0, VetoFrac=0.2 : 2 TeV b-jet t-jet Jet Mass (GeV) Jet-mass cut: cone size 1.0 and 0 < j M < % of top fakes b L needed: 100 fb 1 (2 TeV)

32 W ± Z W and W h W ± Z W : Fully leptonic L : 100 fb 1 (2 TeV) ; 1000 fb 1 (3 TeV) Semi leptonic L : 300 fb 1 (2 TeV) (SM W /Z + 1j large)

33 W ± Z W and W h W ± Z W : Fully leptonic L : 100 fb 1 (2 TeV) ; 1000 fb 1 (3 TeV) Semi leptonic L : 300 fb 1 (2 TeV) (SM W /Z + 1j large) W ± W h: m h 120 : h b b What is b-tagging eff? m h 150 : h W W Use W jet-mass to reject light jet L needed: 100 fb 1 (2TeV) ; 300 fb 1 (3TeV)

34 Conclusions LHC : pp Z W + W, Z h, l + l, (t t, b b) pp W ± t b, Z W, Z h, lν (ongoing work) t t bkgnd sneaks in Probing electroweak KK sector challenging, but possible Warped model with SU(2) L SU(2) R U(1) X Z : A 1, Z 1, Z X 1 W ± : W L, W R Thanks to: Colleagues at BNL : Bill Kilgore, Frank Paige CalcHEP (help from Alaxender Belyaev) Pythia (help from Steve Mrenna, Peter Skands) MadGraph (help from Rikkert Frederix) Bridge (help from Matt Reece)

35 BACKUP SLIDES

36 Z Overlap Integrals Z overlap with Higgs ξ Z overlap with fermions: Define: ξ kπr = 5.83 QL 3 t R other fermions I ξ + 0.2ξ ξ + 0.7ξ ξ 0.2 I 0.2ξ ξ Compared to SM Z couplings to h enhanced (also V L - Equivalence Theorem!) Z couplings to t R enhanced Z couplings to χ suppressed ψ L,R γ µ[ ( eqia 1 µ + g Z T 3 L sw 2 ) T Q IZ1 µ + ( g Z T 3 R s 2 ) ] T Y IZX 1 µ ψ L,R

37 Widths & BR s (For M Z = 2TeV) A 1 Z 1 Z X 1 Γ(GeV) BR Γ(GeV) BR Γ(GeV) BR tt bb ūu dd l + l W + L W L Z L h Total

38 pp Z W + W l ν l ν Cross-section (in fb) after cuts: 2 TeV Basic cuts η l < 2 M eff > 1 TeV M T >1.75 TeV # Evts S/B S/ B Signal WW ττ TeV Basic cuts η l < < M eff < < M T < 5 # Evts S/B S/ B Signal WW ττ # events above is for 2 TeV : 100 fb 1 3 TeV : 1000 fb 1

39 pp Z W + W l ν j j M eff p Tjj + p Tl + /p T M TWW 2 pt 2 jj + mw 2 Diff c.s. [fb/gev] M WW and M TWW 2TeV Z M TWW 2TeV Z M WW SM M WW 1e M WW, M TWW (GeV)

40 pp Z W + W l ν j j Cross-section (in fb) after cuts: M Z = 2 TeV p T η l,j M eff M TWW M jet # Evts S/B S/ B Signal W+1j WW M Z = 3 TeV Signal W+1j WW # events above is for 2 TeV : 100 fb 1 3 TeV : 1000 fb 1

41 pp Z Z h l + l b b (m h = 120 GeV) Cross-section (in fb) after cuts: M Z = 2 TeV Basic p T, η cos θ Zh M inv b-tag # Evts S/B S/ B Z hz b b ll SM Z + b SM Z + b b SM Z + q l SM Z + g SM Z + c M Z = 3 TeV Z hz b b ll SM Z + b SM Z + b b SM Z + q l SM Z + g SM Z + c # events above is for 2 TeV : 200 fb 1 3 TeV : 1000 fb 1

42 pp Z t t Diff c.s. [pb/gev] e-04 1e-05 1e-06 1e-07 Top p T 2TeV Z 3TeV Z SM tt Diff c.s. [pb/gev] e-04 1e-05 1e-06 t t invariant mass 2TeV Z 3TeV Z SM tt 1e p Tt (GeV) 1e M tt (GeV) M Z = 2 TeV Basic p T > < M tt < 2100 Signal SM t t M Z = 3 TeV Basic p T > < M tt < 310 Signal SM t t