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Some recent results from CDF David Stuart U.C. Santa Barbara October 24, 2005.

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Presentation on theme: "Some recent results from CDF David Stuart U.C. Santa Barbara October 24, 2005."— Presentation transcript:

1 Some recent results from CDF David Stuart U.C. Santa Barbara October 24, 2005

2 Tevatron 1 mile pp  pp+pp Eff ~ 10 7 /10 12 Repeat at 1Hz 36 “bunches” each protons/bunch antiprotons/bunch 40  m beam spot.

3 Integrated Luminosity

4 CDF is pursuing a broad physics program QCD QCD Top Top B B EWK EWK New physics New physics QCD QCD Top Top B B EWK EWK New physics New physics My interest is (mostly) in searches for new physics

5 Searching for new phenomena Why? SM is incomplete What? Higgs Supersymmetry Extra generations Extra forces Extra dimensions How? SM++ Why? SM is incomplete What? Higgs Supersymmetry Extra generations Extra forces Extra dimensions How? SM++

6 Searching for a Z’

7 Electron Identification Atypical Z  ee event A typical di-jet event

8 Electron Identification Tracking Detector Electromagnetic calorimeter Hadronic Calorimeter electron photon ++  0  2 photons Require little energy in hadron calorimeter Require little energy in hadron calorimeter

9 Electron Identification Tracking Detector Electromagnetic calorimeter Hadronic Calorimeter electron photon ++  0  2 photons Require little energy around the EM cluster Require little energy around the EM cluster

10 Electron Identification Tracking Detector Electromagnetic calorimeter Hadronic Calorimeter electron photon ++  0  2 photons Require a matching track

11 Electron Identification Tracking Detector Electromagnetic calorimeter Hadronic Calorimeter electron photon ++  0  2 photons Require a matching track

12 Electron Identification Tracking Detector Electromagnetic calorimeter Hadronic Calorimeter electron photon ++  0  2 photons Require a matching track

13 Electron Identification using a likelihood

14 Electron Identification using a likelihood

15 In fact, the electron id differs between “central” and “forward” electrons. In fact, the electron id differs between “central” and “forward” electrons. Reduced tracking in the forward region calls for new techniques. Reduced tracking in the forward region calls for new techniques.

16 Particle Tracking Coverage e+e+ e-e- antiproton proton e+e+ e-e- e-e- e+e+

17 Intermediate Silicon Layers

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19 B B

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22 Forward Electron Tracking Algorithm 1.Form 2 seed tracks, one of each sign, from calorimeter & beam spot

23 Forward Electron Tracking Algorithm 1.Form 2 seed tracks, one of each sign, from calorimeter & beam spot 2.Project into silicon and attach hits using standard silicon pattern recognition

24 Forward Electron Tracking Algorithm 1.Form 2 seed tracks, one of each sign, from calorimeter & beam spot 2.Project into silicon and attach hits using standard silicon pattern recognition 3.Select best  2 match

25 Plug Alignment COT Plug Align plug to COT using the subset of COT tracks which match plug electrons just above |  |=1. Then align silicon to the COT.

26 Plug Calorimeter Alignment Global Internal

27 Obtain ≈1mm resolution

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30 Results from central electrons

31 Results from central muons

32 Limits hep-ex/

33 More recent results

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35 M [GeV/c 2 ] e+e-e+e- Forward-Backward Asymmetry Angular Distribution: sensitive to interference cos 2  cos  p p  e+e+ e-e- Forward Backward + + 2

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37 Limits of about 845 GeV/c 2 for Z’ with SM couplings Next, we could look for other modes Z’      Z’  t t exclude other models Next, we could look for other modes Z’      Z’  t t exclude other models

38 Strong Gravity Geometrical factor generates TeV masses m  m 0  e  kR  where k is a scale of order the Planck scale. kR≈12 generates the observed hierarchy. Similarly, the graviton mass becomes  Pl  e  kR  ≈ 1 TeV Geometrical factor generates TeV masses m  m 0  e  kR  where k is a scale of order the Planck scale. kR≈12 generates the observed hierarchy. Similarly, the graviton mass becomes  Pl  e  kR  ≈ 1 TeV

39 Strong Gravity Coupling  k/M Pl Also  tt, WW, HH, ZZ

40 High Mass Diphoton Search Background is 2/3 dijets, 1/3 . Background is 2/3 dijets, 1/3 .

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42 Other di-boson modes in progress Several modes (eeee, ee, eejj) with potentially very low backgrounds; Z mass constraint rejects background, and SM Z bosons are low p T. Several modes (eeee, ee, eejj) with potentially very low backgrounds; Z mass constraint rejects background, and SM Z bosons are low p T.

43 What else could lead to high p T Z bosons?

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46 Z bosons from GMSB Weak coupling could lead to long life.

47 Z bosons from a 4 th generation quark Weak coupling, V tb’ <<1, could lead to long life.

48 Search for displaced Z’s Search strategy Select dimuons from a Z Require a good vertex measurement (verify efficiency with J/  ’s) Opening angle cut Require p T >30 for Z Aim for simple selection to limit model dependence. (aka, X  YZ) Search strategy Select dimuons from a Z Require a good vertex measurement (verify efficiency with J/  ’s) Opening angle cut Require p T >30 for Z Aim for simple selection to limit model dependence. (aka, X  YZ)

49 Search for displaced Z’s Search strategy Select dimuons from a Z Require a good vertex measurement (verify efficiency with J/  ’s) Opening angle cut Require p T >30 for Z Aim for simple selection to limit model dependence. (aka, X  YZ) Search strategy Select dimuons from a Z Require a good vertex measurement (verify efficiency with J/  ’s) Opening angle cut Require p T >30 for Z Aim for simple selection to limit model dependence. (aka, X  YZ)

50 Search for displaced Z’s Search strategy Select dimuons from a Z Require a good vertex measurement (verify efficiency with J/  ’s) Opening angle cut Require p T >30 for Z Aim for simple selection to limit model dependence. (I.e., X  YZ) Search strategy Select dimuons from a Z Require a good vertex measurement (verify efficiency with J/  ’s) Opening angle cut Require p T >30 for Z Aim for simple selection to limit model dependence. (I.e., X  YZ)

51 Search for displaced Z’s Expect 1.1  0.8, observe 3 A posteriori inspection consistent with background hypothesis. Expect 1.1  0.8, observe 3 A posteriori inspection consistent with background hypothesis.

52 And now for something completely different… While the prospect of a discovery that can lead us to the theory beyond the SM is exciting, the most probable answer in each such measurement is Data - Background = 0. It is appealing to better measure the SM properties along the way.... So, let me tell you about a measurement where we don’t already know the answer. While the prospect of a discovery that can lead us to the theory beyond the SM is exciting, the most probable answer in each such measurement is Data - Background = 0. It is appealing to better measure the SM properties along the way.... So, let me tell you about a measurement where we don’t already know the answer.

53 We can calculate this But what we measure is this p p p p

54 Parton distribution functions u d u u u d p q q p u ≈ 2d, plus much going on in the sea that is incalculable. But, we can measure it. u ≈ 2d, plus much going on in the sea that is incalculable. But, we can measure it.

55 u/d ratio causes an asymmetry in W production

56 Asymmetry in W production complicated by unknown p z Use lepton asymmetry Which convolves production asymmetry with V-A decay.

57 Production asymmetry largest in forward direction, but so is decay asymmetry We use our forward tracking algorithm to probe the |  |>1 region.

58 Electron with E T > 25 GeV Missing E T > 25 GeV 50 < M T < 100 GeV/c 2 No other EMO with E T > 25 GeV to suppress DY and QCD Calorimeter seeded silicon track: We are less worried about acceptance/purity here and more worried about charge identification: # hits >= 4  2 < 8  2 > 0.5 W Event Selection

59 Observed asymmetry (before any corrections) Observed asymmetry (before any corrections)

60 Charge mis-identification Measured with same vs opposite sign electrons from Z  ee Large uncertainty in the forward direction, due to poisson fluctuations, Is the dominant systematic uncertainty Measured with same vs opposite sign electrons from Z  ee Large uncertainty in the forward direction, due to poisson fluctuations, Is the dominant systematic uncertainty

61 Backgrounds Correct for Z  ee (lost leg) W    e QCD fakes Correct for Z  ee (lost leg) W    e QCD fakes

62 Fully corrected asymmetry A(-  ) = -A(  ), with  2 = 9.5/11 dof

63 We can enhance the sensitivity to the production asymmetry We can enhance the sensitivity to the production asymmetry Ideally, we’d reconstruct the W’s direction to avoid the decay smearing… Since we can’t, we instead use the electron’s kinematics: For  e =1.8, e.g., look at y W and x of u quark. Different E T electrons probe different x regions. Ideally, we’d reconstruct the W’s direction to avoid the decay smearing… Since we can’t, we instead use the electron’s kinematics: For  e =1.8, e.g., look at y W and x of u quark. Different E T electrons probe different x regions.

64 We can enhance the sensitivity to the production asymmetry We can enhance the sensitivity to the production asymmetry

65 Compare to existing pdf fits CTEQ6.1m MRST02 PRD 71,

66 The End… …but more to come.

67 Auxiliary slides

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70 What else could lead to high p T Z bosons?

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