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LHCb Activities Edinburgh PPE Meeting

LHCb Activities Edinburgh PPE Meeting. M. Needham 12 th December 2012. Outline. Overview of LHCb Edinburgh activities. Introduction Hardware activities: HPDs Momentum scale calibration + mass studies ϕ s and Bd  J/ ψ K*. Then Dean will talk about charmless decays…. LHCb Detector.

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LHCb Activities Edinburgh PPE Meeting

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  1. LHCbActivities Edinburgh PPE Meeting M. Needham 12th December 2012

  2. Outline Overview of LHCbEdinburgh activities • Introduction • Hardware activities: HPDs • Momentum scale calibration + mass studies • ϕs and BdJ/ψ K* Then Dean will talk about charmless decays…

  3. LHCb Detector Muon System RICH Detectors Vertex Locator VELO pp collision Point ~ 1 cm B Calorimeters Tracking System

  4. LHCb running

  5. LHCb running More than 0.5 billion events with a triggered J/ψsignal candidate on tape

  6. HPD monitoring Dean/Stephen Edinburgh was responsible for testing and quality assurance of the LHCb RICH photodetectors. Now responsible for maintainance Unfortunately, vacuum of tubes degrades and leads to ion feedback (tubes ‘glowing’) Continous campaign of monitoring (which tubes need replacing during TS), replacing and repairing new tubes

  7. Photodetectors for the upgrade For planned LHCb upgrade in 2018 photodetectors will be replaced Candidate is Hammatsu R11265 MaPMT Being characterized in Edinburgh: Haofei/Stephen • Single photoelectron spectra • Gain variation • Cross-talk

  8. QCD @ LHCb • LHCb is more than triangles ! • Great testing ground for QCD studies • QCD is the physics of the LHC • Quarkonia cross-sections, probes of DPS, mass measurements…. • Unique measurements due to forward coverage of LHCb Today mention mass measurements

  9. Pre-warning to Atlas folks The next slides contains images of precision tracking. Phd students on other experiments are required to be accompanied by a supervisor

  10. Momentum scale calibration LHCb Not official Resolution improved by several MeV ! (~ 7 % relative) Phase spaced dependent momentum scale using B+ J/ψ K+ Matthew Needham

  11. b-baryon mass measurement Early 2011 paper: b-hadron masses: An unexpected journey Sequel, coming soon b baryon masses: The desolation of D0 LHCb Not official LHCb Not official LHCb Not official Matthew Needham LHCb Not official D0 did not see the Ωb

  12. D meson mass There and back again… Matthew Needham LHCb Not official LHCb Not official World best measurements…paper for winter conferences LHCb Not official

  13. Bs mixing -D B f  D _ Mixing Parameters B Flavour eigenstates mix to give physical statesBH and BL Observable phases= -2s =M- 2D In the Standard Model expected to be small s= - 0.04 radian Larger values possible in models of New Physics such as Supersymmetry and Little Higgs 13

  14. Measurement of ϕsin Bs J/ • High yield: (25 k signal events/1fb-1 at 7 TeV) • Vector-Vector final state: Admixture of CP eigenstates • Time dependent Angular analysis needed Transversity angles Ω = θ, ϕ, ψ CP Even CP Odd Rob Currie, Pete Clarke, Dianne Ferguson

  15. Measurement of ϕsin Bs J/ Mass distribution Unbinned maximum likelihood fit to mass, time and angles Resolution model from prompt J/ψ Peak. Resolution ~ 50 fs Time acceptance due to cuts in the trigger + reconstruction effects Angular acceptance for signal from simulation Mass sidebands or sWeight technique to determine angular distribution of background Mistag rate measured using B+ J/ψK+ calibration channel

  16. ϕsin BsJ/ Preliminary result presented on 2011 (1 fb-1) dataset for Moriond Final results for 2011 data being prepared: add lifetime biased triggers, same-sign kaon tag, 16

  17. ϕs: Last Christmas ambiguity Resolution Use few % S wave KK present in the sample K+K- P-wave: Phase of Breit-Wigner increases rapidly across ϕ(1020) resonance P wave S wave K+K- S-wave: Phase of Flatté amplitude for f0(980) relatively flat (similar for non-resonance) S - P wave [Y. Xie et al., JHEP 0909:074, 2009] Choose the solution with a decreasing trend of δs- δPvsmKK in the ϕ(1020) mass region Similar to Babar measurement of sign of cos(2β), PRD 71, 032005 (2007)

  18. ϕs: Ambiguity Resolution Background subtracted m(KK) Santa’s present last year Dataset used for the LP result (350 pb-1), open up m(KK) mass cut Perform analysis in four bins of m(KK) and extract phase dependence 1 σ 2 σ Solution I displays the expected decreasing trend

  19. ϕs: Ambiguity Resolution Data favour the Standard Model solution Paper published in PRL

  20. ϕsin BsJ/ Preliminary result presented on 2011 (1 fb-1) dataset for Moriond Final results for 2011 data being prepared: add lifetime biased triggers, same-sign kaon tag, 20

  21. ϕsin BsJ/ Go to paper (soon) ! 21

  22. BdJ/K* Thesis: Ailsa Sparkes Bd Bs Determination of polarization amplitudes CP asymmetries .. LHCb not official Key is understanding acceptance (slow pion from K*) + large sWave Aim for paper in the spring…. 22

  23. Summary • Wide range of activities in the group: not all covered today • LHCb is not just triangles • 5 published papers this year where LHCb-Edinburgh took a leading role • Another 6 coming early next year… Over to Dean….

  24. Backup

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