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Status and Expected Performance of the LHCb Experiment

Status and Expected Performance of the LHCb Experiment. Pascal PERRET Laboratoire de Physique Corpusculaire Clermont-Ferrand Université Blaise Pascal – CNRS/IN2P3 France On behalf of the LHCb Collaboration. 6 th International Conference on Hyperons, Charm and Beauty Hadrons Chicago

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Status and Expected Performance of the LHCb Experiment

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  1. Status and Expected Performance of the LHCb Experiment Pascal PERRET Laboratoire de Physique Corpusculaire Clermont-Ferrand Université Blaise Pascal – CNRS/IN2P3 France On behalf of the LHCb Collaboration 6thInternational Conferenceon Hyperons, Charm and Beauty Hadrons Chicago 3rd July 2004

  2. OUTLINE • Introduction: Physics motivation • LHC • The LHCb experiment • Status of the experiment • Trigger • Physics prospects • Measurement of angle g • Summary and conclusions

  3. Bd0  J/yKS0 Bd0  DK*0 BS0  DSK Bd0  D* p,3p Physics motivation of LHCb SM predicts large CP violating asymmetries for B mesons, in many (often rare!) decays LHCb: dedicated b physics precision experiment of 2nd generation to study CP violation and rare b-decays • Much higher statistics • Access to all b-hadron species: Bd, Bu, Bs, Bc, Λb , … • Overconstrain the unitarity triangles (consistency checks) • Search for New Physics beyond the SM Unitarity Triangles Bd0  p+ p- Bd0  rp BS0  DS p a Bd * * VudVub VtdVtb g b * VcdVcb a * Bs VtdVud * VtbVub b+c New particles may show up in loop diagrams, overconstrain will allow to disentangle SM components from the new-physics ones g-c * c VtsVus b b t BS0  J/y f NP? High statistics is mandatory d d t

  4. Advantage of LHC LHC startup in spring 2007 • pp collisions at √s = 14 TeV, f=40 MHz, multiple pp interactions/bx • Clear objective is to get to 1033 cm-2 s-1 during 2007 operation • Increase luminosity to 1034 cm-2 s-1 in the next few years • total ~ 100 mb, visible ~ 65 mb, bb~ 500 µb, bb/visible = 0.8% • Forward production of bb, correlated LHCb • Single arm spectrometer • 12 mrad <θ< 300 mrad (1,9<η<4,9) • <L>LHCb = 2 x1032 cm-2 s-1 (tunable: controlled beam focus at LHCb IP) • Efficient trigger and clean events 100mb 230mb _  ~1012 bb events per year (107 s) with nominal LHCb luminosity at LHC start-up

  5. LHC Geneva CERN

  6. LHC Dipoles> 300/1200 delivered TI8 - MBIT Short Straight Sections Transfer line installed (2.6 km) 1st beam October TI8 - MBIBV QRL

  7. Efficient trigger for many B decay topologies Leptonic final state → Muon system, ECAL + Preshower Hadronic final state→HCAL High pt-particles with large impact parameter→VELO,TT Efficient particle identification π/K separation (1<p<100GeV) → RICH Good decay time resolution → VELO Good mass resolution → Tracker and Magnet BdK*g BdJ/y r 0 LHCb Requirements HIGH STATISTICS

  8. Muon Stations SPD/PS ECAL Tracking Stations Trigger Tracker Vertex Locator HCAL RICH II Magnet RICH I LHCb detector Construction well progressing 20 m Forward spectrometer (running in pp collider mode)

  9. LHCb status: Vertex Locator Vertex AND Tracking detector • 21 stations, retractable during injection • sensitive area starts at only 8 mm from beam axis • r/φ sensors (single sided, 45º r-sectors) • pitch ranges from 35 μm to 102 μm • 200 μm thin silicon • 180k readout channels 2 halves in a “Roman-pot” sensors 1m PV resolution:~8μm (x,y) and ~44μm (z) IP precision: ~40μm VELO mechanics

  10. LHCb status: Tracking system Tracking system and dipole magnet to measure angles and momenta: • dp/p ~ 0.37 %, • mass resolution ~ 14 MeV (for Bs DsK) • tracking efficiency ~ 94% (for p>10 GeV)  Magnetic field regularly reversed to reduce experimental systematics

  11. Magnet • Warm Al conductor • 4 Tm integrated field • Weight = 1500 tons • 4.2 MW • Assembly of yoke completed • Moving magnet into final position (July 04) • Field map measurements (2004-2005)

  12. Tracking chambers (TT, IT, OT) 320 µm thick sensors 410 µm thick sensors Inner Tracker • 3 stations with 4 layers each • 198 μm readout pitch • 130k readout ch. • 1.3% of sensitive area → 20% of all tracks beam pipe ~1.2x.4 m2 T1 to T3 OT Outer Tracker Trigger Tracker • 3 stations with 4 double layers • 5mm straw tubes • 50k readout ch. IT • Level-1 trigger • KS, low-p tracks TT • 2*2 layers • 410 μm silicon • 198 μm r/o pitch • 144k readout ch. ~6x5 m2 ~1.4x1.2 m2

  13. Tracking chambers (TT, IT, OT) OT Outer Tracker • 3 stations with 4 double layers • 5mm straw tubes • 50k readout ch. Production started

  14. Two RICH detectors for charged hadron identification RICH Aerogel and C4F10 RICH-1: 25-300 mrad RICH-2: 15-120 mrad CF4 BsK+K- p=13%  ε(K→K)=88%; ε(π→K)=3% p=84% ε=79% Provide > 3 σπ–K separation for 3 < p < 80 GeV

  15. RICH RICH2 super structure ready Exit/entrance windows ready 80 mm Photon detector: Hybrid Photodiodes (1024 pixels- LHCb development) ordered RICH 1 : 168 HPD RICH2 : 262 HPD

  16. Calorimeter: SPD,PS,ECAL,HCAL • Identification: electrons, hadrons and neutrals (γ,π0) Readout every 25 ns (L0 trigger) • SPD,PS (2.5X0), ECAL(25X0): 5962 channels (Pb/scintillator) • HCAL(5.6λ): 1468 channels (Iron/scintillator) e 2 resolved clusters h σm(π0γγ) ~ 10 MeV/c2  Conversion (2 merged clusters: ~ 15 MeV/c2) • ECAL: E/E =8.3%/E  1.5% • HCAL: E/E =75%/E  10% (ee) = 95%, (e) = 0.7%

  17. SPD - PS 200 64APMT • PS/SPD modules: ~ 25% completed • Assembly SuperModules: start September

  18. ECAL - HCAL • HCAL modules: ~ 60% completed Installation start December • ECAL modules: 100% completed Installation start November (shashlyk type)

  19. Muon System Muon identification, also used in first level of trigger • 1380 MWPC chambers • Chambers in M2-M5: 4 layers • in M1: 2 layers • x and y projectivity to Interaction Point • 435 m2 • 26 k readout channels • hadron absorber thickness of 20  m  µ id. efficiency ~ 94% for pion misidentification rate <~1%

  20. Muon System FoamPanel Production Automated wiring machine • Production started • 5 sites • ~5% ready Final chamber assembly

  21. Trigger µ: pT >1.1 GeV e: ET >2.8 GeV g: ET >2.6 GeV h: ET >3.6 GeV • sbb ~ 500 mb, < 1% of inelastic cross-section • Use multi-level trigger to select interesting events: high pTelectrons, muons or hadrons vertex structure and pT of tracks full reconstruction HCAL trigger dominates ~ 200 Hz to tape    L0 L1 HLT MUON trigger dominates 30–60%efficiency ECAL trigger dominates

  22. Trigger 40 MHz L0 = synchronized hardware trigger Calorimeter Muon Pile-up Level-0: pT of m, e, h, g 4 µs 1 MHz Vertex Trigger Tracker Level-0 objects Level-1: Impact parameter pT ~ 20% 1 ms 1 800 CPU asynchronous SW trigger 40 kHz HLT: Final state Reconstruction Full detector Information commercial hardware flexible (L1↔HLT) scalable →easy upgrade 200 Hz output

  23. Simulation • MC Pythia 6.2 tuned on CDF and UA5 data, QQ, GEANT3 • 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: • without using MC true information VELO Magnet TT RICH1 • 2003: 67M events produced • 10M inclusive bb events (4 mn of data taking!) • Used for expected physics performance quoted here • 2004: 180M events simulation and analysis in a distributed way (Grid) • Started in May (already ~50M events produced), 3000 jobs/day • Pythia, EvtGen, GEANT4 T1 T2 T3

  24. Efficiencies, event yields and Bbb/S ratios Nominal year = 1012 bb pairs produced (107 s at L=21032 cm2s1 with bb=500 b) Yields include factor 2 from CP-conjugated decays Branching ratios from PDG or SM predictions

  25. bfrom B0 J/ Ks • The ‘gold plated’ channel at B-factories • Precision measurement of this parameter is very important =sin 2b =37% tag=45% eff≈3% B/S=0.8 =0 in SM • LHC(b) will bring a lot of statistics to this channel, which can be used to look into higher order effects, and fit Adir In one year with 240k events: s (sin 2b ) ~ 0.02 Background-subtracted BJ/()KSCP asymmetry after one year Comparing with other channels may indicate NP in penguin diagrams Similar sensitivity ATLAS/CMS

  26. ms from BsDs-(KK)+ =30% tag=55% eff≈9% B/S=0.3 • If NP is present … • Fully reconstructed decay: • Excellent momentum resolution, decay length resolution ~200 µm • Proper time resolution ~40fs Expected unmixed BsDs samplein one year of data taking (fast MC) In one year with 80k events: can observe >5 oscillation signal ifms < 68 ps1 well beyond SM prediction (14.8-26ps1) Once a Bs–Bs oscillation signal isseen, the frequency is precisely determined: (ms ) ~ 0.01 ps-1 ATLAS/CMS: ms < 30 ps1

  27. cfrom Bs J/y f • Bs counterpart of the golden mode B0 J/y KS • measures the phase of Bs mixing • Is not CP eigenstate (VV decay). Angular analysis needed to separate CP-even and CP-odd contributions (fromtransversity angle distribution): needs fit to angular distributions of decay final states as a function of proper-time (good proper-time resolution is essential) • In SM expected asymmetry  sin 2c= very small ~ 0.04 sensitive probe for new physics • Reconstruct J/y m+m- or e+e-, f  K+K- In one year with 120k events: s (sin 2c) ~ 0.06, s( DGs/ Gs) ~ 0.02

  28.  from B and BsKK • In both decays large b d(s) penguin contributions to bu • Measure time-dependent CP asymmetries in B and BsKK decays: ACP(t)=Adir cos(m t) + Amix sin(m t) • Exploit U-spin flavour symmetry for P/T ratio [Fleischer] • Use measure of c from B0 J/y fand bfrom B0 J/ Ks • 4 measurements (CP asymmetries) and 3 unknowns (, d and )  can solve for  • Good p/K identification 37 k Bbb/S=0.3 26 k Bbb/S<0.7 B BsKK In one year : s (g) = 4-6 deg U-spin symmetry assumed; sensitive to new physics in penguins

  29.  from B DK* and B DK* • B DCPK*: interference between 2 tree diagrams • Application of Gronau-Wyler method [Dunietz]: √2 A2 √2 A2 A3 2 A3  A1 = A1 • Measure 6 decay rates (following three + CP-conjugates) • No proper time measurement or tagging required • assumes DCP = (D + D )/2 In one year : s (g) = 7-8 deg =65o, =0 sensitive to new phase in DCP state

  30.  from Bs Ds K+ • Interference between 2 tree diagrams (again) via Bs mixing • Measure -2cfrom time-dependentrates:BsDs K(b  c) andBsDsK(b  u) (+ CP conjugates) • Use 2cfrom Bs J/y f • Mistag extracted from BsDs sample 5.4 k B/S<1 Bs Dsπ is background for Ds KBranching ratio ~ 12  higher In one year : s (g) = 14-15 deg The two Bs-Bs asymmetries after 5 years of data No theoretical uncertainty;insensitive to new physics in B mixing

  31. Interest in over-constraining the CKM UT New physics in angle  measurement ? 1.Bs  DsK 2.B , Bs KK 3.B  DK*  not affected by new physics  affected by possible new physics in penguin  affected by possible new physics in D-D mixing Extract the contribution of new physics to the oscillations and penguins Determine the CKM parameters A,, independent of new physics

  32. Other physics at LHCb • New physics in b  s penguin processes • B0 K*g, B0f KS ,Bs ff, KK, fg, … • Bs0 J/y h, Bs0 J/y h, , … • Direct CP violation:Bu K*r(v), ... • Rare decays • Bs m+m- ,B0d K*0m+m- (cf talk from S. Viret) • Bc physics • Lifetime, mass, branching fractions • g measurements from Bc D Ds difficult! • b baryons • …

  33. Conclusion • LHCb is dedicated to the study of b physics • a devoted trigger • excellent vertex and momentum resolution • excellent particle identification • Access to all b-hadron species: Bu, Bd, Bs, Bc , Lb … • LHCb detector will be ready for data taking in 2007 at LHC start-up • Construction of the experiment is progressing well • installation of detectors starts this year • Already in year one, LHCb will have competitive measurements on b, g, c, Dms and other parameters LHCb offers an excellent opportunity to spot New Physics signals beyond the Standard Model very soon at LHC

  34. Are Penguins New Physics Guards? NP NP

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