Disentangling the Origins of New Gauge Bosons at the ILC S. Godfrey, Carleton University Workshop on Possible Parity Restoration at High Energy Jun , 2007, IHEP, Beijing

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 2 Outline Models of new physics Discovery and Identification at the LHC Z’ Discovery and identification at the ILC W’ Discovery and identification at the ILC Final Comments References: G. Weiglein et al. [LHC/LC Study Group] Phys. Rept. 426, 47 (2006) [hep-ph/ ] TESLA TDR hep-ph/ A. Leike, Phys. Rept. 317, 143 (1999) [hep-ph/ ] M. Cvetic and S. Godfrey, hep-ph/

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 3 Many Models of New Physics Extended gauge sectors Extra U(1) factors: Left-Right symmetric model: “Un-unified” Model: Little HiggsLittle Higgs TopcolourTopcolour Extra dimensions (ADD, RS, UED…): KK excitationsExtra dimensions (ADD, RS, UED…): KK excitations ADD: Graviton tower exchange effective operators: Randall-Sundrum Gravitons: Discrete KK graviton spectrumRandall-Sundrum Gravitons: Discrete KK graviton spectrum Ununified Extra Dimensions (UED)Ununified Extra Dimensions (UED) Many, many models

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 4 Left Right Symmetric Models Expect: Higgs Multipletswith an expanded Higgs sector, eg Extra Gauge Bosons:  depends on Higgs content of the model with  =1 for Higgs doublets and  =2 for Higgs triplets Will focus on phenomenology of gauge bosons see Mohapatra Raychaudhuri Martins Simoes Wu

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 5 The little Higgs models are a new approach to stabilize the weak scale against radiative corrections Little Higgs Arkani-Hamed et al hep-ph/ TeV 1 TeV 100 GeV New Strong Dynamics Global Symmetry Symmetries Broken Pseudo-Goldstone Scalars New Gauge Bosons related to SU(2): New Heavy Top cancels quadratic divergences Light Higgs SM vector bosons & fermions Han, Logan, McElrath, Wang, Phys.Rev.D67:095004,2003. [hep-ph/ ] Han, Logan, Wang, JHEP 0601:099,2006. [hep-ph/ ] Need to experimentally identify the little Higgs Mechanism Also need to identify the particular little Higgs model Study properties of

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 6 Un-Unified Model: Left handed Quarks and Leptons transform as doublets under separate SU(2) groups q R and l R are singlets under both SU(2) q and SU(2) l Parametrize by  - the mixing angle of charged gauge bosons 3 rd Family Model: Quarks and Leptons of 3rd family transform as doublets under a separate SU(2) h group Effective Rank 5 E 6 Model: Many Other Models: Georgi, Jenkins, Simmons, PRL 62, 2789 (1989) Barger, Rizzo PL B206, 133 (1988)

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 7 What do these models have in common? Spin 1 appear in many models: Z’ in string inspired models Z’, W’ in extended gauge sectors Z R, W R in left-right symmetric models Z KK,  KK, W KK, in theories with extra dimensions Z H, W H in Little Higgs Models Also possible higher spin states: Gravitons in theories with extra dimensions String resonances And scalar states: Radions Graviscalars They all have new s-channel structure at ~TeV scale

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 8 Likely that discoveries at the LHC will get us started But will need the ILC to discriminate between models Possible Routes: Direct Discovery Indirect discovery assuming specific models Indirect tests of New Physics via L eff Tools: Di-fermion channel Anomalous gauge boson couplings Anomalous fermion couplings Higgs couplings How do we discover the new physics?How do we discover the new physics? How do we identify the new physics?How do we identify the new physics?

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 9 Z’  production New Z’ Gauge Bosons at the LHC: [T. Martin] p p q b µ+µ+ µ-µ- , Z 0, Z’ Di-lepton Resonance Search Select 2 opposite sign high p T isolated leptons and examine invariant mass distribution If you find a peak: quantify its significance Measure its  x BR

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 10 If you don’t: Derive upper limit on  x BR Constrain models Di-lepton Resonance Search

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 11 SLH KK LH    Z’  production Discovery Limits for Z’ Gauge Bosons at the LHC [Godfrey hep-ph/ ]

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 12 LHC Discovers dilepton s-channel Resonance !! Eureka! May be seen very early: first weeks What is it? Many possibilities for s-channel resonance See Brooijmans

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 13 How do we distinguish them? Assume the LHC discovers a single heavy resonance Tools to determine what it is: Cross sections & Widths Angular Distributions Couplings (decays, polarization…)

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 14 LHC can give some information: Z’: Rizzo, hep-ph/ Invariant Mass Distributions: [Azuelos et al, hep-ph/ ] Z’  production

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 15 Forward Backward Asymmetries Dittmar, Nicollerat, Djouadi, hep-ph/ LHC can resolve to some extent Han, Logan, Wang, JHEP 0601:099,2006. [hep-ph/ ]

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 16 What about the ILC? Advantages of ILC Precision well defined energy well known initial state High luminosity Excellent particle ID Clear event signatures Polarization of e-, e+ gives helicity information e  and  options also being considered New resonances lead to new s- and t-channel contributions ILC is the ideal facility to measure this

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 17 M Z’ =750 GeV Z  Z LR Z ALR e + e -  ff -e f +

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 18 Many observables: Sensitive to flavour Sensitive to helicity

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 19 Numerous difermion observables 18 di-fermion observables:

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 20 Discovery vs Exclusion 2  Exclusion Limits (95% C.L.) 2  vs 5  Limits

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 21 Dependence on measurement precision [From TESLA TDR]

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 22 95% C.L. bounds L=1 ab -1  L=0.2%, P - =0.8, P + =0.6,  P=0.5% Extraction of Z’ couplings assuming M Z’ is known from LHC Z’ Identification Note sign ambiguity S. Riemann: TESLA TDR & LHC/LC Study

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 23 What else can we learn? Godfrey, Kalyniak, Tomkins hep-ph/

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 24 The Importance of Polarization No polarization Only electron electron & positron

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 25 What happens for higher mass?

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 26 How does it change with more observables?

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 27 What happens with higher energy?

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 28

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 29 If the Z’ is too heavy Or if couplings to quarks small The distance from the SM helps determine the model and the mass Measurement at several  s to disentangle mass and couplings L=1ab -1 L=50fb -1 What happens if Z’ not detected at LHC? S. Riemann

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 30 Off Resonance: Interference of exchange of virtual graviton KK states with SM amplitudes Leads to deviations in dependent on both  and s/M H Indirect Signatures for Gravitons SM Hewett, hep-ph/ Can use multipole moments to distinguish spin 2 from spin 1 Rizzo: hep-ph/

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 31 Search and Identification of W’ Limits from LHC up to ~5.9 TeV assuming SM strength couplings But very model dependent In e + e - consider two processes:

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 32 Search and Identification of W’ Left-Right Symmetric Model: Un-Unified:

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 33 In e + e - : Search and Identification of W’ Kinematic cuts to reflect detector acceptance: Radiative Bhabba-scatter with e lost down beam: Where mrad is minimum angle for veto detector SG, Kalyniak, Kamal, Leike, PR D61, (2000)

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 34 Sensitive to W’ but also to Z’ Peaks are due to Z’ +

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 35 d  / dE  depends on W’ model sensitivity to W’ LRM SSM(W’+Z’) KK eLeL eReR

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 36 Limits not competitive with LHC But if LHC discovers them can measure their couplings

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 37 Constraints on Couplings: Z’ Constraints on Couplings: Z’ Includes systematic errors

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 38 Constraints on Couplings: W’e Constraints on Couplings: W’e

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 39 Varying M W’

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 40 No Z’ in process to complicate picture Sensitive to both q and l couplings Can enhance t-channel exchange by imposing cut that q is collinear to beam Can then approximate with simpler process Results are consistent with exact calculation Convolute with either WW or backscattered laser spectrum SG, Kalyniak, Kamal, Doncheski, PR D63, (2001)

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 41 SM, LR UUM KK SSM M W’ =750 GeV Backgrounds: 2 jets with one lost down the beam Can be eliminated with: SM

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 42 Exclusion Limits for W’ using e  qq At  s=500 GeV, in general not competitive with LHC LR model already ruled out by Tevatron Higher limits from e  mode argument for e  collider At  s=1 TeV KK, UUM, and SSM competitive or surpass LHC e+e-e+e- ee

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 43

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 44 Constraints on W’ couplings from e  qq Assume W’ discovered at LHC Results for backscattered laser mode 95% C.L. contours SSM KK LR SM KK SSM LR

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 45

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 46Summary Extra gauge bosons are a feature of many theories of physics Beyond the Standard Model If the LHC discoveries such a state the ILC will be an extremely powerful tool for disentangling it’s origins Depending on M Z’ the ILC would be able to determine the origins of the Z’ and determine if it arose from Parity Restoration at high energy Precision measurements of ILC crucial for this: Many independent observables give high resolving power Polarization to study different helicities

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 47 SM Interference of exchange of virtual graviton KK States with SM amplitudes Eg. A LR Hewett, hep-ph/

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 48 Measuring Little Higgs Parameters M H not known from LHC s’ fixed J. Conley, M.P. Le, J. Hewett

S. Godfrey, Carleton University Disentangling the Origins of New Gauge Bosons at the ILC 49 Follows del Aguila, Cvetic and Langacker, PR D48 R969 (1993) Godfrey & Cvetic, [hep-ph/ ]