Presentation is loading. Please wait.

Presentation is loading. Please wait.

Exotica: Overview of the Searches for New Vector Boson High Mass States Cory Fantasia PY898 03/30/09.

Similar presentations


Presentation on theme: "Exotica: Overview of the Searches for New Vector Boson High Mass States Cory Fantasia PY898 03/30/09."— Presentation transcript:

1 Exotica: Overview of the Searches for New Vector Boson High Mass States Cory Fantasia PY898 03/30/09

2 The Exotic: Z′ W′ RS Graviton

3 3 Particles Z′ W′ RS Graviton

4 Z′ Models Sequential Standard Model (SSM)  Same Coupling Strength as SM Z  Simplest extension of SM  Basis for this talk Littlest Higgs E6 and SO(10) Grand Unifying Theories Kaluza-Klein Excitation of SM Z

5 Z′ - Tevatron Dilepton channel  Z′ → ee  Z′ → μμ  Z′ → ττ  Z′ → t tbar With 450 pb -1 CDF limits SSM Z′ to 825 GeV  Dielectron / dimuon channels most powerful  Other models are less strict on mass

6 Search Z′ → μμ Channel will offer first glimpse of signal Using first data assumptions  Misalignment  Larger uncertainties

7 Decay Modes - Z′ Z′ → ee Z′ → μμ Z′ → WW  Harder to utilize

8 Background Z′ Photons  Require track QCD Jets  Require isolation  Require > 90% of energy to be in ECAL  Require hits in muon system Require oppositely charged leptons Drell-Yan (irreducible) – find mass peaks

9 Discovery

10 Z′ →WW Peak resolution more difficult Clearest channel  WW → eν jj  Allows for discrimination between two W’s  Aids in background suppression Background  W + jets

11 Discovery - Z′ → WW Using Cuts  |η| < 2 for jets  ET of W > M(Z′)/3  Reconstructed W’s good mass values (|diff| < 15) Assumes coupling falls off like 1/m(Z′) fb -1

12 3 Particles Z′ W′ RS Graviton

13 W′ Sequential Standard Model Same couplings as W  Makes signal more difficult to extract  MET is now a factor

14 W′ - Tevatron Results Using W′ → eν or W′ → t bbar Minimum mass set to 788 GeV using 205 inv pb -1  Set with leptonic decays

15 W′ → μ ν Require single muon Isolation >13 hits along track Largest source of background is SM W  Must use reconstructed mass peak

16 Discovery Discovery potential with 1 fb -1 up to 3.5 TeV

17 W′ → e ν Largest source of background comes from SM W decays  Use similar cuts to resolve mass peak  Isolated, tracked

18 W′ → WZ → 3l + ν Resolution (with no cuts) decreases with increasing mass W′ still visible past 2 TeV with 300 fb -1 W ′ → WZ → 3l + ν  Opposite signed leptons form Z  Leaves lepton + MET to form W

19 Background WZ → 3l + ν  Mass peak distinction ZZ → 4l  1 lepton missed (shows up as MET) tt → Wb Wb  b quark yields a lepton plus 2 from W’s  b lepton won’t be isolated

20 W′→ WZ Discovery 300 fb -1 Using worst case model to obtain 5 sigma assuming coupling falls off like 1/m(W′) 2

21 W′ (Higgsless) W′ Z → WZZ → jj4l Remove reconstructed Z mass (oppositely charged leptons) Remaining WZ mass shows peak

22 Cuts - W′ Z → WZZ → jj4l Require large (>4) η separation between jets  Reduces gluon jet background E j > 300 GeV p Tj > 30 GeV p Tl > 10 GeV

23 Discovery - Higgless Larger cross section of WZjj offers chance of quicker discovery as the mass of the W′ increases

24 3 Particles Z′ W′ RS Graviton

25 Motivation?  Explain Weakness of Gravity Difference between Planck mass and TeV Scale  Unify Gravity with other forces

26 Theory Lisa Randall and Raman Sundrum 15 Orders of Magnitude between M planck and TeV scale Expand Universe to 5 th Dimension  Scales ~ e -kπR  kR ~ 11  k ≡ curvature of new dimension  R ≡ is the size of the dimension

27 Theory TeV Brane → Planck Brane  SM interactions exist on TeV Brane Can propagate in 5-D  SM particles fixed between these branes  Since Higgs is on TeV Brane, the closer a SM particle lies to TeV Brane the larger its mass  “Naturally” form mass hierarchy

28 Production c ≡ k/M planck  Dominate factor is graviton interactions

29 Discrimination – RS Spin 2 particle  Different angular distribution  Use θ * Angle between quark and lepton G → ee  High energy electron jets

30 End Caps are Critical for Discrimination

31 Signal over Background E > 100 GeV Isolated 2 Hit Track > 90% of energy in ECAL

32 Discovery CMS c = 0.01 (green) c = 0.02 (blue) c = 0.05 (pink) c = 0.1 (red) With similar cuts  Isolated  High Energy

33 Discovery CMS Depending on the coupling parameter discovery could come with 1 fb -1

34 Conclusions Z′ muonic decay offers best hope seeing signal early  Subsequent use of electron decay for confirmation and refinement of signal W′ searches will require more work  MET in the final state RS Graviton offers exciting answers but will need a more careful analysis


Download ppt "Exotica: Overview of the Searches for New Vector Boson High Mass States Cory Fantasia PY898 03/30/09."

Similar presentations


Ads by Google