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The LHCb experiment: status and physics program

The LHCb experiment: status and physics program. Clara Matteuzzi On behalf of the LHCb collaboration Università Milano-Bicocca and I.N.F.N. Milano. FPCP Paris, 2-6 June 2003. The LHCb experiment. LHCb is a forward one-arm spectrometer dedicated mainly to

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The LHCb experiment: status and physics program

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  1. The LHCb experiment: status and physics program Clara Matteuzzi On behalf of the LHCb collaboration Università Milano-Bicocca and I.N.F.N. Milano FPCP Paris, 2-6 June 2003 Clara Matteuzzi

  2. The LHCb experiment LHCb is a forward one-arm spectrometer dedicated mainly to study CP violation and rare B decays at LHC Check consistency of theStandard Model : precision measurements of angles and sides of the CKM triangle Search for New Physics : rare and SM forbidden decays of b particles Clara Matteuzzi

  3. 2008 LHCb 2007 now Bdpp BdJ/yKS BsJ/yf BsDsK The triangle Present status Consistency of the Standard Model (assumed to determine the vertex) and the direct measurement of sin2β from B-factories |Vcb| from BHcX decays A |Vub| from BHuln decays r2+h2 Bd-Bd mixing, Dmd(1-r)2+h2 Clara Matteuzzi

  4. New physics Db = 1: Decays through penguin Db = 2 : Oscillations through box through tree b d, s newparticles b d, s l or l d,s b newparticles b d, s l or l newparticles d,s b The Standard Model tree process not affected. Clara Matteuzzi

  5. (IP1,IP5) b at the LHC machine Luminosity locally controlled All types of b-hadrons Bu , Bd , Bs , Bc , Lb , Sb, Xb,... with large boost of the hadron Clara Matteuzzi

  6. b -physics at LHC Crucial tasks of a detector: triggering particle IDidentification of exclusive final states (K/p/p/e/m)tagging background rejection decay time resolution Clara Matteuzzi

  7. The LHCb detector layout Aperture ~ 15 – 300 (250) mrad 1.5 < | h | < 3.5 Inner Tracker • 3 stations 4 layers each • 320 μm thin silicon • 198μm readout pitch. • 130k readout channels. Ecal 70% modules produced Hcal (15% modules produced) • Shashlik type • (66layers 2mm Pb/4mm scintillator) • Transverse granularity 4,6,12 cm cells • ~6000 channels , 25Xo • σ/E ~ 10%/sqrt(E) Outer Tracker m chambers MWPCs ~1.41.2 m2 • Fe + scintillator tiles • 1468 cells, 5.6lI • σ/E ~ 75% / sqrt(E) ~65 m2 • 3 stations with4 double layers • 5mm straws tubes • Fast drift gas (signal within 50 ns) 75% Ar 15%CF410%CO2 • 50k readout channels. • Dipole magnet : • Warm trapezoidal coils • pole shape following the • acceptance •  Bdl = 4 Tm • P = 4.2 MW 40% Xo , 12% lI Clara Matteuzzi

  8. The LHCb Vertex Locator 21 stations • low occupancy • Si area : 0.32 m2 • #Xo : 0.18 • st : 43 fs • # channels : 172 k Clara Matteuzzi

  9. Tracking performance Average efficiency = 92 % Efficiency for p>5GeV >95% Momentum resolution: Dp/p=0.38% Ghost rate pT>0.5 GeV~ 7%. <N> = 27 tracks/event Mass resolution (~13 MeV) Proper time resolution (42 fs) for the decay channel Bs Dsp+ KKπ Clara Matteuzzi

  10. RICH 1 (25-300 mrad) 5cm aerogel 4m3 C4F10 TheRICHof LHCb • detectors with 3 radiators • (aerogel, C4F10, CF4) • cover momentum range: • 2 - 100 GeV K-p separation RICH 2 (15-120 mrad) 100 m3 CF4 Clara Matteuzzi

  11. Physics with Particle Identification BsDsK BsK+K- Purity=13% Purity=7.0% Purity=84% Efficiency=79% Purity=66% efficiency=88% Clara Matteuzzi

  12. subdetectors LHCb Trigger CalorimetersMuon Pile-up veto 40 MHz Level-0 pT of e, m, h ,g VELO Trigger Tracker Level-0 Impact parameter Rough pestimate ( ~20%) Level-1 1 MHz all the detector final statereconstruction Higher Levels 40 KHz data log 200 Hz Clara Matteuzzi

  13. LHCb L1 trigger Performance in B decays • trigger robust and flexible • hadron trigger fundamental for hadronic final states • trigger efficiencies L0xL1 20 % - 70% Clara Matteuzzi

  14. Simulated bb events MC Pythia 6.2 tuned on CDF and UA5 data Multiple pp interactions and spill-over effects included Complete description of material from TDRs Individual detector responses tuned on test beam results Complete pattern recognition in reconstruction Clara Matteuzzi

  15. Event yield in LHCb 1 year = 2 fb -1 (L = 2x1032 cm–2s-1) • Yield calculated taking into account : • Geometrical acceptance, detection efficiency, material • L0 and L1trigger efficiencies (including pile-up veto) • Reconstruction efficiencies (tracking, calorimeters, PID) • Selection cuts efficiency to identify the final state more background simulated events are necessary to optimize selection criteria vs background rejection Clara Matteuzzi

  16. Measuring g 4 ways of determining g • Time dependent analysis ofBsD+sK- (tagged) • Rate difference between B-DoK- and B+DoK+ (untagged) model independent • Rate measurements in Kopand Kp (Fleisher-Mannel)or rates in Kopand asymmetry in Kpo (Neubert-Rosner, Beneke et al). • Measure time dependent asymmetries in (Fleischer,Martinelli) Bop+p-and BsK+K-symmetric d s dependence on hadronic assumptions in the different calculations Clara Matteuzzi

  17. Measuringg withBs Ds±K+ Bs vtx resolution (mm) Bs Ds–p+ • must be separated from • (~15 times larger Br) • hadronic trigger, K/π separation, proper time resolution are fundamental • gets g2dg • (needs 2dg from Bs–>J/Ψ Φ ) • In one year of data (2 fb-1) • 8k Ds K and 72k Dsπ Dsmass resolution (GeV) expected sensitivity: () ~ 100 for Dms = 20 ps–1 () ~ 120 for Dms = 30 ps–1 depending on amplitudes, strong phases,γ, Δms, ΔΓ/Γ Bs Ds–p+ measure Bs oscillations Δmsup to~ 60 ps-1 Clara Matteuzzi

  18. B0s J/()  signal prompt J/() background (mm K+K–) Study of B0s J/ • CP asymmetries determine –2δγ (very small in Standard Model but sensitive to New Physics). And also Δms and ΔΓs • Must be separated from prompt J/Ψ production (possible with0.1 < B/S < 0.4 at 90% CL ) Clara Matteuzzi

  19. expected sensitivity: σ(2δγ) ~ 20 for Dms = 20 ps–1 Study of B0s J/ (mm K+K–) • Needs angular analysis to disantangle CP-odd and CP-even states • In one year of data (2 fb-1) • 109k J/Ψ Φ and 19k J/Ψ Φ • (mm) (ee) also B0sΦΦ B0s J/Ψ η B0s ηcΦprobeδγ (under study in LHCb) Clara Matteuzzi

  20. 92% purity 96% purity 98% purity B0 K B0s KK B0  Measuringg with B(s) pp,K p,K K • Relies on hadronic trigger, excellent K/π separation, mass resolution • Select B candidates with pT, IP/σ, L, mass cuts • Combinatorial bb bckgr. can be rejected (S/B > 1) σ(γ) ~ 30 for xs = 20 Clara Matteuzzi

  21. Present estimate of LHCb Physics reach These numbers are being updated, and more channels studied, in the re-optimization of the LHCb detector to be concluded in September 2003 1 year data 2 fb–1 Clara Matteuzzi

  22. Conclusions The present of b-physics is already very rich The future : Next generations of dedicated experiments at hadron machines will have order of 1012bb pairs per year with dedicated trigger and particle ID B-factories (BaBar, Belle, CLEO), Tevatron, + (LEP, SLC) LHCb is a unique opportunity to measure precisely angles and sides of the CP triangle and to understand the origin of CP violation in the SM and beyond LHCb installation starts in 2005 data taking starts in 2007 Clara Matteuzzi

  23. Back-up slides Clara Matteuzzi

  24. LHCb TRIGGER B0s J/()  B0s J/(ee)f B0s Ds K B0d K* g B0dp+p– Clara Matteuzzi

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