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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 FPCP, 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 Clara Matteuzzi FPCP, Paris 2-6 june 2003 Present status The triangle Consistency of the Standard Model (assumed to determine the vertex) and the direct measurement of sin2β from B-factories |Vcb| from BHcX decays A |Vub| from BHuln decays r2+h2 Bd-Bd mixing, Dmd (1-r)2+h2 Clara Matteuzzi BdJ/yKS Bdpp BsJ/yf B s D sK FPCP, Paris 2-6 june 2003 New physics Db = 1: Decays through penguin b Db = 2 : Oscillations through box b d,s new particles d, s new particles b through tree d,s d, s b l or l d, s new particles l or b l The Standard Model tree process not affected. Clara Matteuzzi FPCP, Paris 2-6 june 2003 b at the LHC machine Ecm (IP1,IP5) 14 TeV L(cm-2 s-1) 2x s (bb) s (inel) 500 mb 80 mb #bb-pairs b fraction f t bunch z primary inter/xing 1012 /year 5 x 10-3 40 MHz 25 ns 5 cm 0.4 (2-20) Clara Matteuzzi 1032 (10-100) Luminosity locally controlled All types of b-hadrons Bu , Bd , Bs , Bc , Lb , Sb , Xb,... with large boost of the hadron FPCP, Paris 2-6 june 2003 b - physics at LHC Crucial tasks of a detector: triggering particle ID (K/p/p/e/m) identification of exclusive final states tagging background rejection decay time resolution Clara Matteuzzi FPCP, Paris 2-6 june 2003 Aperture Dipole ~ 15 –magnet 300 (250): mrad The 1.5 < | Outer Tracker LHCb detector layout trapezoidal coils h |•• Warm < 3.5 pole shape following Inner the Tracker acceptance 3 stations 4 layers each • Bdl = 4 Tm 3 stations with 4 double • P layers = 4.2 MW 320 μm thin silicon 5 mm straws tubes 198 μm readout pitch. Fast drift gas (signal within 50 ns) 130k readout channels. 75% Ar 15%CF410%CO2 50k readout channels. m chambers MWPCs ~65 ~1.41.2 m2 m 2 Ecal 70% modules produced Hcal (Shashlik 15% modules produced) type (66layers 2mm Pb/4mm scintillator) Fe + scintillator tiles Transverse granularity 4,6,12 cm cells 1468 cells, 5.6 lI ~6000 channels , 25 Xo 40% Xo , 12% σ/E lI ~ 75% / sqrt(E) Clara Matteuzzi σ/E ~ 10%/sqrt(E) FPCP, Paris 2-6 june 2003 The LHCb Vertex Locator low occupancy Si area : 0.32 m2 #Xo : 0.18 st : 43 fs # channels : 172 k s IP 21 stations 32 m m 17 m m + pT Clara Matteuzzi FPCP, Paris 2-6 june 2003 Tracking performance Average efficiency = 92 % Efficiency for p>5GeV >95% Ghost rate pT>0.5 GeV ~ 7%. Mass resolution (~13 MeV) for the decay channel Momentum resolution: Dp/p=0.38% <N> = 27 tracks/event Proper time resolution (42 fs) Bs Ds p+ KKπ Clara Matteuzzi FPCP, Paris 2-6 june 2003 The RICH of LHCb 2 detectors with 3 radiators (aerogel, C4F10, CF4) cover momentum range: 2 - 100 GeV K-p separation RICH 1 (25-300 mrad) Clara Matteuzzi 5 cm aerogel 4 m3 C4F10 RICH 2 (15-120 mrad) 100 m3 CF4 FPCP, Paris 2-6 june 2003 Physics with Particle Identification Bs Ds K Bs K+KPurity=13% Purity=7.0% Purity=66% efficiency=88% Clara Matteuzzi Purity=84% Efficiency=79% FPCP, Paris 2-6 june 2003 subdetectors Level-0 Calorimeters Muon Pile-up veto Level-1 VELO Trigger Tracker Level-0 Higher Levels all the detector data log Clara Matteuzzi LHCb Trigger 40 MHz pT of e, m, h ,g 1 MHz Impact parameter Rough p estimate ( ~20%) 40 KHz final state reconstruction 200 Hz FPCP, Paris 2-6 june 2003 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 FPCP, Paris 2-6 june 2003 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 FPCP, Paris 2-6 june 2003 Event yield in LHCb 1 year = 2 fb Yield calculated taking into account : -1 (L = 2x1032 cm–2s-1) Channel Yield B0 p+p- 27 k B0 K+ p- 115 k B s K+ K- 35 k L0 and L1trigger efficiencies (including pile-up veto) Bs Ds-p+ 72 k Reconstruction efficiencies (tracking, calorimeters, PID) Bs J/y (m-m+ )f 109 k Bs J/y (e-e+ )f 19 k B0 J/y(m-m+) KS 119 k Geometrical acceptance, detection efficiency, material Selection cuts efficiency to identify the final state Bs Ds-K+ B0K0* g 8k 20 k more background simulated events are necessary to optimize selection criteria vs background rejection Clara Matteuzzi FPCP, Paris 2-6 june 2003 Measuring g 4 ways of determining g Time dependent analysis of BsD+sK- (tagged) Rate difference between B-DoK- and B+DoK+ (untagged) model independent Rate measurements in Kop and Kp (Fleisher-Mannel) or rates in Kop and asymmetry in Kpo (Neubert-Rosner, Beneke et al) . Measure time dependent asymmetries in (Fleischer,Martinelli) Bop+p- and BsK+K- symmetric d s dependence on hadronic assumptions in the different calculations Clara Matteuzzi FPCP, Paris 2-6 june 2003 Measuring must be separated from (~15 times larger Br) Bs Ds g –p+ with Bs Ds±K+ Bs vtx resolution (mm) 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 Ds π Ds mass resolution (GeV) expected sensitivity: Dms = 20 ps–1 for Dms = 30 ps–1 s(g) ~ 100 for s(g) ~ 120 depending on amplitudes, strong phases, γ, Δms, ΔΓ/Γ Bs Ds–p+ measure Bs oscillations Clara Matteuzzi Δms up to ~ 60 ps-1 FPCP, Paris 2-6 june 2003 Study of B0 s J/y f (mm K+K–) 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 with 0.1 < B/S < 0.4 at 90% CL ) prompt J/y(mm) background Clara Matteuzzi B0s J/y(mm) f signal FPCP, Paris 2-6 june 2003 Study of B0 s J/y f (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) expected sensitivity: σ(2δγ) ~ 20 for also B0s ΦΦ B0s J/Ψ η Dms = 20 ps–1 B0s ηcΦ probe δγ (under study in LHCb) Clara Matteuzzi FPCP, Paris 2-6 june 2003 Measuring g with B(s) p p, 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) 92% purity B0 p+p- 96% purity B0 K+p- σ(γ) ~ 30 for Clara Matteuzzi 98% purity B0s K+K- xs = 20 FPCP, Paris 2-6 june 2003 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 2 fb–1 1 year data Channel b Bd J/y Ks g Bs Ds K Bd pp, Bs KK Yield Precision 119 k s(b) 0.6o 8k 27 k, 35 k s(g) 10o s(g) 3o a 2dg Bd p+p- 27 k s(a) 5o- 10o Bs J/y f 128 k s(2dg) 2o |Vtd/Vts| Bs Ds p 72 k Dms up to 58 ps-1 rare decays Bd K* g 20 k Clara Matteuzzi FPCP, Paris 2-6 june 2003 Conclusions The present of b-physics is already very rich B-factories (BaBar, Belle, CLEO), Tevatron, + (LEP, SLC) The future : Next generations of dedicated experiments at hadron machines will have order of 1012 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 LHCb installation starts in 2005 data taking starts in 2007 Clara Matteuzzi FPCP, Paris 2-6 june 2003 Back-up slides Clara Matteuzzi FPCP, Paris 2-6 june 2003 LHCb TRIGGER channel L0 (%) m e h g B0s J/y(mm) f 90 5 30 3 B0s J/y(ee) f 7 36 24 4 B0s Ds K 8 5 37 2 6 28 30 47 B0d K* g 7 9 55 3 B0d p + p– Clara Matteuzzi all 93 52 44 82 61 L1(%) Total (%) 73 68 43 23 65 29 33 27 51 31 FPCP, Paris 2-6 june 2003