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Intae Yu

Recent Results on Heavy Flavor and Electroweak Physics at Hadron Colliders. Intae Yu. Sungkyunkwan University Focused Session @ KPS , Oct 21 th , 2011. Reference: EPS2011 talks & Lepton Photon 2011 talks. Accelerator Operation. LHC delivered 5.3 fb -1 (2011.10.18)

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Intae Yu

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  1. Recent Results on Heavy Flavor and Electroweak Physics at Hadron Colliders Intae Yu Sungkyunkwan University Focused Session @ KPS , Oct 21th, 2011 Reference: EPS2011 talks & Lepton Photon 2011 talks

  2. Accelerator Operation • LHC delivered 5.3 fb-1 (2011.10.18) • Inst. Lum = 2.4 ×1033 cm-2 s-1 (2011.7) • Tevatron has delivered 12 fb-1 during Run II ( ended on Sep 30, 2011) • Inst. Lum = 4 ×1032 cm-2 s-1 (2011.7)

  3. New Central calorimeters Solenoid Central muon Old Front end Trigger DAQ Offline Partially new TOF Endplug calorimeter Silicon and drift chamber trackers Forward muon Particle Detectors at Tevatron CDF Detector D0 Detector • CDF with better tracking and particle Identification (PID) • D0 with better calorimetry and lepton coverage

  4. Particle Detectors at LHC CMS Detector ATLAS Detector • CMS with better tracking and electromagnetic calorimetry • ATLAS with better hadron calorimetry

  5. LHCb Detector at LHC LHCb Detector • LHCb optimized for flavor physics • Dedicated heavy flavor trigger, precise vertexing, excellent PID (RICH) • LHCb operating luminosity (3×1032cm-2s-1) << LHC design luminosity • Reduce multiple interactions → less combinatorial background

  6. Heavy Flavor Production

  7. Quarkonium Production at LHC – J/ψ(nS), Υ(nS) J/ψ Upsilon • Large cross sections of quarkonium production • → Help to understand production mechanism (color singlet? octet?..) • Differential cross section measurement using 2010 data (~37 pb-1) • More to come using 2011 data (polarization, higher states,…)

  8. Quarkonium Production – X(3872) CDF 2.4fb-1 • Measurement of relative production of ψ(2S) and X(3872) at CMS • R = 0.087±0.017(stat)±0.009(syst) from 2010 data (~40 pb-1 ) • Mass measurement at LHCb • MX(3872) = 3871.96±0.46(stat)±0.10(syst) MeV/c2 from 2010 data • (3871.61±0.16(stat)±0.19(syst) MeV/c2 from CDF)

  9. Quarkonium Production – X(4140) 14±5 events • Narrow resonance in m(J/ψKK) – m(J/ψ) observed at CDF • in B+→J/ψφK+ decays with significance of ~ 3.8 • LHCb does not confirm this structure yet • → 2.4 difference from CDF result

  10. b-Quark Production at LHC • b production studies through various channels (dileptons, J/ψ,..) • Good agreements with Fixed Order NLL QCD predictions

  11. Bottom Baryons at Tevatron • Reconstruct Ξb-(0) through cascade decays • with , , and • Mass measurement of Ξb-(0) • M(Ξb0 ) = 5787.8±5.0(stat)±1.3(syst) MeV/c2 • M(Ξb0 ) - M(Ξb- ) = 3.1±5.6(stat)±1.3(syst) MeV/c2

  12. Bottom Baryons at LHCb • First observation of Λb →D0 p K- ( another mode for γ measurement) • Evidence of Ξb0 → D0 p K- ( consistent with CDF mass, ~2.6σexcess)

  13. B Decays

  14. Two-body Chamless B Decays at CDF • Two-body charmless B decays Sensitive to CKM angle γ significant contribution from penguin decays provides sensitivity to new physics (NP) • First evidence for Bs →π+π- • Br = (0.57±0.15(stat)±0.10(sys))×10-6 • Agree with pQCD estimates • First bounds for B →K+ K- • Br ∈ [0.05, 0.46] ×10-6 @ 90% CL

  15. Two-body Chamless B Decays at LHCb • Excellent PID using RICH at LHCb • Acp(B0 → Kπ) = -0.088±0.011±0.008 Consistent with world average -0.098±0.011 • Acp(Bs0 → Kπ) = 0.27±0.08±0.02 (0.39±0.17 @ CDF)

  16. B0 →K*μ+μ- Decays • Probe helicity structure in B0 →K*μ+μ- and search for NP especially forward-backward asymmetry (AFB) as a function of lepton invariant mass (q2) ~300 K*ll events • AFB consistent with SM @ LHCb can determine cross point sensitive to NP

  17. Bs Mixing Phase • CPV phase φs in Bs → J/ψφ probes NP Earlier CDF results show some deviation (~ 2σ) from SM 0.8σfrom SM 1σfrom SM • Analysis is under progress using ~ 350 pb-1 @ LHCb Sensitivity to be improved by including CP-eigenstate Bs → J/ψf0(980)

  18. Dimuon Charge Asymmetry at D0 • D0 reported the anomalous like-sign charge asymmetry using 6.1fb-1 • , • Absl= (-0.957±0.251(stat)±0.146(syst)) × 10-2 3.2σfrom SM 3.9σfrom SM • Updated results from D0 (impact parameter dependent analysis) • Absl= (-0.787±0.172(stat)±0.093(syst)) × 10-2

  19. Search for New Physics in Bs System • Absland CPV phase φs in Bs → J/ψφ have interesting connections. • , , • Absland φs measurements are consistent

  20. Bs/Bd → μ+μ- at CDF • SM rate is small and well understood. NP can enhance the rate. • Updated CDF analysis : improved Neural Network (NN) and more data • Br(Bd → μ+μ-) < 6×10-9 @ 95% CL (SM prediction 1.1×10-10 ) • Br(Bs → μ+μ-) ∈ [0.46,3.9]×10-8 @ 90% CL (SM prediction 3.2×10-9 ) • Assuming signals, Br(Bs → μ+μ-) = 1.8+1.1-0.9×10-8 (~ 2.8σ)

  21. Bs/Bd → μ+μ- at CMS • Cut-based Analysis • 1.14 fb-1 • No excess observed • Br(Bd → μ+μ-) < 4.6×10-9 @ 95% CL • Br(Bs → μ+μ-) < 1.9 ×10-8 @ 95% CL ( CDF 1.8×10-8 )

  22. Bs/Bd → μ+μ- at LHCb • Boost Decision Tree (BDT) out of 9 kinematical and topological variables • Train BDT on MC, Calibrate on data (sidebands, B→hh) • Br(Bd → μ+μ-) < 5.2×10-9 @ 95% CL • Br(Bs → μ+μ-) < 1.5 ×10-8 @ 95% CL (CMS/LHCb Combined: 1.1×10-8 , CDF: 1.8×10-8 )

  23. Top Physics

  24. Top Quark Production at LHC • Top quark pair production via gluon fusion at LHC At Tevatron, quark-antiquark annihilation dominates • Top events are classified by the W decay modes

  25. Top Quark Production at LHC • Measurements of the cross section agree with QCD predictions l+jets dilepton

  26. Single Top Production • Single top production via electroweak interaction t channel Wt channel s channel • t channel contribution is dominant at LHC. • Measure single top production in each channel using event structures

  27. Single Top Production • Multivariate methods are used to discriminate signals from backgrounds and other single top events.

  28. Top Quark Mass • Tevatron combination gives an uncertainty below 1 GeV • New electroweak fit constraints on Higgs mass (< 161 GeV/c2 @95% CL)

  29. Top-AntiTop Charge Asymmetry • NLO QCD predicts an asymmetry for produced via annihilation Top quark is emitted along the direction of incoming quark Exchange of new particles can modify the asymmetry forward-backward asymmetry center - forward asymmetry

  30. Top-AntiTop Charge Asymmetry at Tevatron • CDF measured the and Δy dependence of the asymmetry Larger asymmetry observed in high mass and large rapidity difference • No clear mass dependence in D0 data

  31. Top-AntiTop Charge Asymmetry at LHC • LHC results are consistent with SM prediction • Different variables : ATLAS (Δy), CMS (Δη)

  32. Electroweak Physics

  33. Vector Boson Production • First measurements of W/Z production at LHC • Systematic uncertainties dominate

  34. Z Differential Cross Sections • Z Pt distributions sensitive to radiative effects • Z angular distributions sensitive to production processes

  35. W Charge Asymmetry • W charge asymmetry depending on PDF of u and d quarks at Tevatron • W charge asymmetry sensitive to quark and anti-quark densities at LHC

  36. W Mass • W mass measurement requires deep understanding of the detector (especially lepton momentum and missing Et) • ΔMW= 23 MeV (world average) → ~12 MeV (expected from Tevatron Run II combined) → ?? MeV (LHC) • Challenges at LHC : pile-up, PDF, energy calibration, etc → W Pt distribution, Z mass measurements

  37. Summary • LHC experiments, especially LHCb, begin to produce physics results comparable to or better than Tevatron results on heavy flavor frontier. • During the Tevatron run II (2002~2011), CDF and D0 contributes significantly to understanding heavy flavor and EW physics. • LHC accelerator has delivered 5/5/1 fb-1 to CMS/ATLAS/ LHCb experiments respectively. • Some anomalies in dilepton charge asymmetry and top pair charge asymmetry are observed although their significances are not large yet • More interesting results will be expected from LHC by 2012 when the size of data is increased by several times.

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