1. Clara MatteuzziFPCP, Paris 2-6 june 2003 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

2. Clara MatteuzziFPCP, Paris 2-6 june 2003 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 the Standard Model : precision measurements of angles and sides of the CKM triangle Search for New Physics : rare and SM forbidden decays of b particles

3. Clara MatteuzziFPCP, Paris 2-6 june 2003 The triangle Consistency of the Standard Model (assumed to determine the vertex) and the direct measurement of sin2β from B-factories Present status |V cb | from B  H c X decays  A |V ub | from B  H u decays      B d -B d mixing,  m d      now 2007 2008 LHCb B d  J/  K S B d  B s  J/  Bs DsKBs DsK

4. Clara MatteuzziFPCP, Paris 2-6 june 2003 new particles  b = 1: Decays through penguin  b = 2 : Oscillations through box through tree new particles bd, s b new particles d,sb b b l or l or l The Standard Model tree process not affected. New physics

5. Clara MatteuzziFPCP, Paris 2-6 june 2003 b at the LHC machine E cm 14 TeV L(cm -2 s -1 ) 2 x 10 32 (10-100)  (bb) 500  b  (inel) 80 mb #bb-pairs 10 12 /year b fraction 5 x 10 -3 f 40 MHz t bunch 25 ns z primary 5 cm inter/xing 0.4 (2-20) (IP1,IP5) Luminosity locally controlled All types of b-hadrons B u, B d, B s, B c,  b,  b,  b,... with large boost of the hadron

6. Clara MatteuzziFPCP, Paris 2-6 june 2003 b - physics at LHC Crucial tasks of a detector: triggering particle ID identification of exclusive final states (K/  p/e/  ) tagging background rejection decay time resolution

7. Clara MatteuzziFPCP, Paris 2-6 june 2003 The LHCb detector layout 1.5 < |  | < 3.5 Aperture ~ 15 – 300 (250) mrad Hcal ( 15% modules produced )  Fe + scintillator tiles  1468 cells, 5.6 I  σ/E ~ 75% / sqrt(E)  Shashlik type (66layers 2mm Pb/4mm scintillator)  Transverse granularity 4,6,12 cm cells  ~6000 channels, 25 X o  σ/E ~ 10%/sqrt(E)Ecal 70% modules produced Dipole magnet : Warm trapezoidal coils pole shape following the acceptance  Bdl = 4 Tm P = 4.2 MW  chambers MWPCs 40% X o, 12%  I ~1.4  1.2 m 2 ~6  5 m 2  3 stations 4 layers each  320 μm thin silicon  198 μm readout pitch.  130k readout channels. Inner Tracker  3 stations with 4 double layers  5 mm straws tubes  Fast drift gas (signal within 50 ns) 75% Ar 15%CF 4 10%CO 2  50k readout channels. Outer Tracker

8. Clara MatteuzziFPCP, Paris 2-6 june 2003 The LHCb Vertex Locator  low occupancy  Si area : 0.32 m 2  #X o : 0.18   t : 43 fs  # channels : 172 k 21 stations

9. Clara MatteuzziFPCP, Paris 2-6 june 2003 Tracking performance Average efficiency = 92 % Efficiency for p>5GeV >95% Ghost rate p T >0.5 GeV ~ 7%. Mass resolution (~13 MeV) (~13 MeV) for the decay channel B s  D s  + KKπ Momentum resolution:  p/p=0.38% Proper time resolution (42 fs) resolution (42 fs) = 27 tracks/event = 27 tracks/event

10. Clara MatteuzziFPCP, Paris 2-6 june 2003 The RICH of LHCb 2detectors with 3 radiators (aerogel, C 4 F 10, CF 4 ) cover momentum range: 2 - 100 GeV RICH 1 5 cm aerogel 4 m 3 C 4 F 10 (25-300 mrad) K  separation RICH 2 100 m 3 CF 4 (15-120 mrad)

11. Clara MatteuzziFPCP, Paris 2-6 june 2003 B s D s K Purity= 66 % efficiency= 88 % Physics with Particle Identification B s K + K - Purity= 7.0 % Purity=13% Purity=84% Efficiency=79%

12. Clara MatteuzziFPCP, Paris 2-6 june 2003 LHCb Trigger Level-0 Higher Levels data log 40 MHz 1 MHz 40 KHz 200 Hz Calorimeters Muon Pile-up veto VELO Trigger Tracker Level-0 Level-1 all the detector p T of e, , h,  Impact parameter Rough p estimate ( ~20%) final state reconstruction subdetectors

13. Clara MatteuzziFPCP, Paris 2-6 june 2003 LHCb L1 trigger Performance in B decays  trigger robust and flexible  hadron trigger fundamental for hadronic final states for hadronic final states  trigger efficiencies L0xL1 20 % - 70% 20 % - 70%

14. Clara MatteuzziFPCP, Paris 2-6 june 2003 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 Simulated bb events

15. Clara MatteuzziFPCP, Paris 2-6 june 2003 Event yield in LHCb ChannelYield B0  B0   27 k B 0  K    115 k B s  K  K  35 k Bs DsBs Ds 72 k Bs Ds-K+Bs Ds-K+ 8 k B s  J /      109 k B s  J /  e - e   19 k B 0  J /      K S 119 k B 0  K 0   20 k 1 year = 2 fb -1 ( L = 2x10 32 cm –2 s -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

16. Clara MatteuzziFPCP, Paris 2-6 june 2003 Measuring  4 ways of determining   Time dependent analysis of B s  D + s K  ( tagged )  Rate difference between B -  D o K - and B +  D o K + (untagged) model independent  Rate measurements in K o   and K     (Fleisher-Mannel)  or rates in K o   and asymmetry in K    (Neubert-Rosner, Beneke et al)    Measure time dependent asymmetries in (Fleischer,Martinelli) B o     and B s  K  K  symmetric d s dependence on hadronic assumptions in the different calculations

17. Clara MatteuzziFPCP, Paris 2-6 june 2003 with B s  D s ± K +  (  ) ~ 10 0 for  m s = 20 ps –1  (  ) ~ 12 0 for  m s = 30 ps –1 Measuring   must be separated from (~15 times larger Br) D s mass resolution (GeV) B s vtx resolution (mm)  gets    (needs 2  from B s –>J/Ψ Φ )  hadronic trigger, K/π separation, proper time resolution are fundamental  In one year of data (2 fb -1 ) 8k D s K and 72k D s π expected sensitivity: depending on amplitudes, strong phases, γ, Δm s, ΔΓ/Γ B s  D s –  + measure B s oscillations Δm s up to ~ 60 ps -1 B s  D s –  +

18. Clara MatteuzziFPCP, Paris 2-6 june 2003 Study of B 0 s  J/    Must be separated from prompt J/Ψ production (possible with 0.1 < B/S < 0.4 at 90% CL ) prompt J/  (  ) background B 0 s  J/  (  )  signal  K + K – )  CP asymmetries determine –2δγ (very small in Standard Model but sensitive to New Physics). And also Δm s and ΔΓ s

19. Clara MatteuzziFPCP, Paris 2-6 june 2003 Study of B 0 s  J/    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 (  ) (ee) σ(2δγ) ~ 2 0 for  m s = 20 ps –1 expected sensitivity:  K + K – ) also B 0 s  ΦΦ (under study in LHCb) B 0 s  η c Φ probe δγ B 0 s  J/Ψ η

20. Clara MatteuzziFPCP, Paris 2-6 june 2003 Measuring  with B (s)   K   K K σ(γ) ~ 3 0 for x s = 20  Relies on hadronic trigger, excellent K/π separation, mass resolution  Select B candidates with p T, IP/σ, L, mass cuts  Combinatorial bb bckgr. can be rejected (S/B > 1) 92% purity 96% purity98% purity B0 B0  B 0  K    B 0 s  K  K 

21. Clara MatteuzziFPCP, Paris 2-6 june 2003 Present estimate of LHCb Physics reach ChannelYieldPrecision  B d  J /  K s 119 k  0.6 o  B s  D s K B d  , B s  KK 8 k 27 k, 35 k  10 o  3 o  Bd  Bd   27 k  5 o - 10 o  B s  J /  128 k  2 o |V td /V ts  B s  D s  72 k  m s up to 58 ps  rare decays B d  K   20 k 1 year data 2 fb –1 These numbers are being updated, and more channels studied, in the re-optimization of the LHCb detector to be concluded in September 2003

22. Clara MatteuzziFPCP, Paris 2-6 june 2003 Conclusions The present of b- physics is already very rich The future : Next generations of dedicated experiments at hadron machines will have order of 10 12 bb pairs per year with dedicated trigger and particle ID 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 B-factories (BaBar, Belle, CLEO), Tevatron, + (LEP, SLC) LHCb installation starts in 2005 data taking starts in 2007

23. Clara MatteuzziFPCP, Paris 2-6 june 2003 Back-up slides

24. Clara MatteuzziFPCP, Paris 2-6 june 2003 LHCb TRIGGER channel L0 (%)  e h  all L1(%)Total (%) 905 30 3 7 36 24 4 8 5 37 2 6 28 30 47 7 9 55 3 93 52 44 82 61 73 43 65 33 51 68 23 29 27 31 B 0 s  J/  (  )  B 0 s  J/  (ee)  B 0 s  D s K B 0 d  K*  B0d  + –B0d  + –