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High mass bump searches in Drell-Yan spectrum at CDF

High mass bump searches in Drell-Yan spectrum at CDF. By Tracey Pratt. CDF Detector Drell-Yan & Signatures for New Physics Present Limits and Run II reaches First Run II Data Future Plans. April 02. Supervisor: Todd Huffman, Oxford University Advisor: Kaori Maeshima, FNAL

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High mass bump searches in Drell-Yan spectrum at CDF

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  1. High mass bump searches in Drell-Yan spectrum at CDF By Tracey Pratt • CDF Detector • Drell-Yan & Signatures for New Physics • Present Limits and Run II reaches • First Run II Data • Future Plans April 02 Supervisor: Todd Huffman, Oxford University Advisor: Kaori Maeshima, FNAL Presented work by Tracey Pratt, Oxford and Koji Ikado, Waseda University

  2. pp collisions CDF at Fermilab CDF CDF Main Injector Tevatron D0

  3. CDF Run I and Run II overview Run I consisted of Run 1a (88/89) and Run 2b (92-95) In total 110pb-1 of data was collected Centre of mass energy 1.8 TeV Since the shutdown in 1996, the Tevatron and CDF have undergone major upgrades Run II started in June 2001 Centre of mass energy 2 TeV

  4. Barrel Muon Chamber CDF Detector - what’s new Silicon Microstrip Tracker Old Partially New New Muon System Time-of-Flight Central Calorimeter Plug Calorimeter Solenoid

  5. p q q p */ Z qq */ Z l+l- l+ l- Drell-Yan (DY) • The Drell-Yan process probes the parton distribution • functions (pdfs) of the protons at the scale Q2 = M*/ Z2 • Low background at high dilepton invariant mass • Distinctive signatures: • two oppositely charged leptons produced • have a high transverse momentum • are isolated • originate from a single interaction point • For */Z production :  q fq q(x1)q(x2)

  6. New Physics Searches with DY Looking for deviations to the Standard Model at high invariant mass • New Gauge Bosons (Z') • Extra Dimensions • Quark-lepton Compositeness • Technicolor (T , T )

  7. d2/dMdy 101 100 10-1 10-2 10-3 10-4 Z and   only 0 100 200 300 400 Invariant Mass in GeV/c2 Run I Drell-Yan (DY) • AFB smaller than SM • AFB dips beyond 200 GeV/c2 X88/89 CDF Run 1 dileptons (ee+ 4pb-1) o 92-95 CDF Run 1 dimuons (107.4pb-1)

  8. Run 1 Z' limits set limits for Z' ll, with 110pb-1, in both dielectron and dimuon channels CDF Run I (110pb-1), for MZ > 600 GeV/c2(Z ).BR(Z ->ll) is 40 fb. which excludes MZ withStandard Model coupling < 690 GeV/c2 (Phys. Rev. Lett.79: 2192-2197, 1997))

  9. Run II Extrapolated limits Extrapolating from Run I, with 2 fb-1, the predicted Z' mass reach could be extended to 900 GeV/c2 with s =1.8 TeV assuming Standard Model couplings and to about 1000 GeV/c2 with s =2.0 TeV

  10. New parameters: • First graviton excitation mass: m1 • A Ratio: k/MPl Extra Dimensions ADD model ***references • New parameters: • String Scale: Ms = MPl(4+n) • A Factor:  ( = ±1) RS model L.Randall and R.Sundrum, Phys. Rev. Lett. 83,3370 (1999), Phys. Rev. Lett. 83,4690 (1999) Graviton Exchange - modifies the rate and angular distribution of high-mass Drell-Yan events

  11. 10 -2 10 -4 10 –6 10 -8 d/dM (pb/GeV) K/MPl 1 0.7 0.5 0.3 0.2 0.1 RS model 200 400 600 800 1000 1200 Mll (GeV) SM prediction Quantum Gravity Model for Ms values CDF results for dimuon samples ADD model and RS model limits 700 GeV KK graviton Run I Compactification scales R-1 (TeV)  0.9 Run 1 at 95% C.L., 1.2 Run II,6.7 LHC (one large extra dimension) (hep-ph/9905311) Effective Planck Scale lower limit (95% C.L.) 0.9-1.5 TeV Run I 1.3-2.5 TeV Run IIa, 1.7-3.5 TeV LHC Range corresponds to number of extra dimensions n=7-2. (hep-ph/9909218)

  12. Compositeness Compositeness Quark-lepton contact interaction was searched for in Run I in the dimuon and dielectron channels, by looking for an excess of dileptons compared to the Drell-Yan prediction. Run Ib dielectron data set the limits on the compositeness scale to - > 3.8 TeV and + > 2.6 TeV. In Run II we expect to be able to explore up to limits of approximately 5 TeV. (Where +/- corresponds to the constructive / destructive interference with the dominant up-quark contribution to the cross-section.) (Phys. Rev. Lett.79: 2198-2203, 1997))

  13. Run II Run II officially began on March 1st 2001 Started taking “physics quality” data from June 2001 • CDF Upgrade improvements for Drell-Yan measurements • Dielectron channel • New plug calorimeter • Dimuon channel • Increased muon chamber coverage • Improved Dimuon Background Rejection in run II

  14. Time-Of-Flight (ToF) Detector in CDF 216 scintillator bars located just outside the COT Expected time resolution is  100 ps.

  15. ToF Cosmic-Ray Rejection For high mass dimuon sample the dominant background at high invariant mass is from cosmic rays Tupper – Tlower ~ 2L/c for CR dimuons ~ 0 for interaction dimuons as for dielectrons Above plots are from uncalibrated ToF. Calibration work is in progress. Expected time resolution is  100 ps.

  16. Run II data Run II officially began on March 1st 2001 Started taking “physics quality” data from June 2001 Z Zee

  17. Total Luminosity So Far ~2 week shutdown in June to install 2 new stochastic cooling tanks in the pbar accumulator, aim is to give us higher luminosity and a smaller transverse pbar beam size

  18. Future Plans It is hoped that approximately 50-70 pb-1 data will be collected by Summer 2002 And  150 pb-1 by end of 2002. We hope to find new physics or set new limits using the dilepton channels.

  19. The END That’s All Folks!

  20. Run 1 limits on Z' production

  21. CDF Run II Detector  = 1.0  = 1.5  = 2.0  = 3.0 ToF Silicon Tracker Fiber Tracker Drift Chamber Scintillator EM Cal. Hadronic Cal. Solenoid Coil Toroid Steel Shielding Key:

  22. CDF Upgrades for Run II New Silicon tracking System: SVX II: 5 layers, 96cm, r-phi and r-z ISL: 2 additional layers, covers |eta| < 2 L00 : (Addition of stereo capability to SVX, 3D Vertex and ~ 2 more acceptance) New central drift chamber: (And strengthened COT stereo capabilities, maintain Run 1 track eff and resolution) Improved and integrated tracking system New deadtimeless Trigger (track trigger moved to Level 1 and use Silicon info at L2) Improved Calorimeter: resolution, efficiency and coverage New Plug calorimeter, out to || = 2. Extra Muon coverage Luminosity monitor Electronics Higher center of mass energy Addition of a ToF detector

  23. SM prediction Quantum Gravity Model for Ms values CDF results for dimuon samples ADD model ADD model: Effective Planck Scale lower limit 0.9-1.5 TeV Run I (at 95% C.L.) 1.3-2.5 TeV Run IIa and 1.7-3.5 TeV LHC Range corresponds to number of extra dimensions n=7-2. (hep-ph/9909218)

  24. 10 -2 10 -4 10 –6 10 -8 d/dM (pb/GeV) 1 0.7 0.5 0.3 0.2 0.1 RS model 200 400 600 800 1000 1200 Mll (GeV) RS model Extra Dimensions Tevatron 700 GeV KK graviton K/MPl RS model: Compactification scales R-1 (TeV)  0.9 Run 1 at 95% C.L., 1.2 Run II,6.7 LHC (one large extra dimension) (hep-ph/9905311)

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