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Physics Potential of LHCb

Explore advanced studies in physics at LHC focusing on CKM parameters, CP measurements, rare B-decays, and search for new physics beyond the Standard Model. Discover requirements to detectors for high statistics and efficient trigger systems.

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Physics Potential of LHCb

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  1. Physics Potential of LHCb ADVANCED STUDIES INSTITUTE PHYSICS AT LHC 6 - 12 July 2003, Prague

  2. Physics Motivation • Precise determination of the CKM parameters through phase measurements • Search for New Physics beyond the SM by overconstraining the Unitarity Triangles • high precision CP measurements including • pure hadronic and multibody final states • measure CP in new decay channels • including Bs decays • look for rare and loop-suppressed B-decays • trigger and reconstruct many different channels • 2BdJ/ KS • 2+Bd D*  •  and  Bd    , Bs  K K • -2Bs Ds K • 2 BsJ/   Bd    Bd    other Bd  K*  Bd  K*  Bs   ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  3. b d, s d,s b Example for manifestation of New Physics u, c, t Bd : arg M12= 2 + bdNP CP in Bd  J/ KS sin (2 + bdNP) CP in Bd  D* sin (2 +  + bdNP) b d, s new particles u, c, t d,s b Bs : arg M12= 2 + bsNP CP in Bs  J/ sin (2 + bsNP) CP in Bs  DsK sin (2 +  + bsNP)   can be disentangled from New Physics effects ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  4. 1 yr LHCb 2007 now Bdpp BdJ/yKS BsJ/yf BsDsK Discovery potential with one year of LHCb 2007 |Vtd/Vts| B-factories and Tevatron  • and  poorly known |Vub/Vcb| 1 yr LHCb  ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  5. - • LHC: • pp collisions at s = 14 TeV • total ~ 100 mb  interaction rate ~ 2 x107/s • multiple pp interactions per bunch crossing • inel~ 80 mb, bb~ 500 b  S/B ~ 1% • forward production of bb, correlated bb angular production - – _ • ~1012 bb events per year with full efficiency at LHC start-up B production at LHC inelastic pp interactions per bunch crossing • LHCb: • single arm spectrometer •  12 mrad <  < 300 mrad (1.8 <  < 4.9) • efficient trigger and clean events, • minimize radiation damage •  work mostly with single interactions • at a nominal L~2x1032cm-2s-1 tunable! • (defocussed beams at LHCb IP) ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  6. Requirements to Detector BdK*g HIGH STATISTICS BdJ/y r 0 • efficient trigger for many B decay topologies leptonic final states  Muon System, ECAL+Preshower (e.g. J/ KS) hadronic final states  HCAL (e.g. , K, DsK etc.) high pt -particles with large impact parameter  Vertex Locator, Trigger Tracker • efficient particle identification  RICH (K separation between 1GeV<p<100GeV) • good decay time resolution  Vertex Locator (e.g. ~40fs for BsDs and B) • good mass resolution  Tracker and Magnet (e.g. 14MeV for BsDs, 18MeV for Bd) ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  7. Overview and Status of Detector • LHCb Letter of Intent  Feb 1996 • Technical Proposal approved  Sep 1998 • Technical Design Reports of all detector subsystems  2000–2002 • LHCb re-optimization & Trigger TDRs Sep 2003 • detector construction has started in 2002 Aperture: ~15–300 (250) mrad 1.8 < |  | < 4.9 40%Xo , 12% lI ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  8. 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 Status of Simulation VELO TT Magnet event from GEANT3 simulation T1-T3 • All numbers preliminary, final numbers in re-optimization TDR in September ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  9. Magnet • dipole • warm Al conductor • 4 Tm integrated field • 4.2 MW • 1450 t yoke • All components delivered • Underground assembly ongoing ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  10. Vertex Locator (VELO) • 21 stations, retractable during injection • sensitive area starts at only 8 mm • from beam axis • R/φ sensors (single sided, 45º sectors). • pitch ranges from 37 μm to 103 μm. • 220 μm thin silicon. • 180k readout channels stand-alone tracking! sensors r-sensors -sensors beam- pipe SCTA RF-box Beetle Al window ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  11. Impact Parameter Resolution impact parameter resolution vs pT Primary Vertex: z ~ 47m x ~ y~ 8 m average decay length: 1 cm for Bd track multiplicity vs pT ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  12. Proper Time Resolution measure Bs mixing with >5 up to 48 ps-1 (xs=75) in 1 year Proper time resolution for BsDs: ~ 44 fs ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  13. Main Tracker (TT, IT, OT) Inner Tracker • 3 stations with • 4 layers each • 320 thin silicon • 198 readout pitch • 130k readout ch. Outer Tracker ~65 m2 Trigger Tracker • 3 stations with • 4 double layers • 5mm straw tubes • 50k readout ch. ~1.41.2 m2 • 2*2 layers • 500 silicon • 198 r/o pitch • 144k readout ch. ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  14. Tracking Performance Ghost rate vs pTcut Efficiency vs p Ghost rate vs pcut Long Tracks Long Tracks Long Tracks average ghost rate ~ 9% for pT>0.5 GeV/c => ghost rate ~ 3%. for p>10 GeV => efficiency > 94% ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  15. Momentum and Mass resolutions <p> resolution B-tracks σ = 0.37% momentum resolution vs p mass resolution for BsDs Ds->KK  ~ 14 MeV/c2 ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  16. Particle Identification with RICH • Requirements: • Background suppression => high momentum hadrons in two-body B decays • B flavour tagging (identify K from bcs) => low momentum hadrons • RICH system divided into 2 detectors ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  17. RICH detectors RICH1 5cm aerogel n = 1.03 4 m3 C4F10 n = 1.0014 RICH2 100 m3 CF4 n = 1.0005 (construction started) Super-Structure Exit Window Entrance Window Mirrors Photon Detectors Magnetic Shielding ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  18. RICH performance [for selected Bs Ds(KKp) K] ( 2< p< 100 GeV )  separation between  and K hypothesis vs p ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  19. Background rejection with RICH BsKK Bs Ds K ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  20. Requirements: • Preshower (PS) and • Scintillator Pad Detector (SPD): • PID for L0 electron and photon trigger • electron,photon/pion separation by PS • photon/MIP separation by SPD • charged multiplicity veto by SPD • ECAL: • Et of electrons and photons for L0 trigger • (e.g. BJ/ Ks, B K*) • reconstruction of 0 and prompt  offline • particle ID • HCAL: • Et of hadrons for L0 trigger • (e.g. B, B DsK) • particle ID • L0 trigger => Calorimeters readout every 25ns Calorimeters Y~7m X~8.5m PS/SPD HCAL ECAL Z~2.7m ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  21. Calorimeters ECAL (70% delivered) 5952 channels, 25 X0 “shashlik” type modules 66 layers of 2mm Pb/ 4mm scintillator readout via WLS fibers Preshower (production started) 2.5 X0 lead converter sandwiched between two scintillator planes with 2x5952 scintillating pads HCAL (15% delivered) 1468 channels, longitudinal-tiles, 5.6  6mm master/4mm spacer, 3mm scintillator readout via WLS fibers ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  22. Calorimeters performance Energy resolution of series modules measured in testbeam HCAL ECAL  E E E GeV ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  23. m(0) ~ 9 MeV/c2 Performance on selected B+-0 Two resolved clusters One merged cluster m(0) ~14 MeV/c2 conversions combined reconstruction efficiency ~50% ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  24. Performance on selected B+-0 Two resolved clusters One merged cluster m(B+ -0) ~72 MeV/c2 m(B+-0) ~72 MeV/c2  ~75 fs  ~75 fs ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  25. ECAL E( ) /P nearest cluster Electron identification Preshower E-deposit Combined PID with Calorimeters and RICH [from selected BsJ/(ee)KS] physics performance: El. Eff. = 78% ;  mis-ID rate 1.0% • ~95% for electrons (within calo acceptance) BsJ/(ee)  misidentification rate ~0.7% ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  26. Muon system Requirements: Identify and trigger on muons from decay of B-mesons: B X In particular: BdJ/(+-) Ks ; BsJ/(+-)  ; Bs +- • 4 (1) stations with 4 (2) layers/station • stations M1+M2 for Pt measurement, • M2+M3 for trigger track seed, • M4+M5 for muon track finding • 435m2 of detector area, 1380 chambers • ~26k readout channels • hadron absorber thickness of 21  HCAL ECAL MWPC Muon Stations ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  27. ~90% for muons (within muon system acceptance)  misidentification rate ~1% Muon identification [from selected BsJ/()KS] Bs  J/() physics performance:  Eff. = 86%  mis-ID rate 1.0% ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  28. pile-up B BsDsK Signal Min. Bias Trigger strategy 40 MHz  Level-0 Calorimeters Muon System Pile-up veto pT of  , h, e,  1 MHz  Level-1 Vertex Locator Trigger Tracker Level-0 objects impact parameter rough pT (~20%) 40 KHz  High-Level Full detector information final state reconstruction 200 Hz  Output ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  29. commercial hardware • flexible (L1 HLT) • scalable  easy upgrade Trigger implementation L0 = synchronized hardware trigger L1 = CPU based, asynchronous software trigger, common design with High-Level Triggerand DAQ ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  30. L0 efficiency (%) on ‘selected’ events e, m h all B->pp 8 16 51 57 Bs->DsK 10 12 44 52 Bs->J/y(ee)KS 6 35 23 48 Bs->J/y(mm)f 89 9 21 90 Bs->K*g 10 70 34 76 L1 and L0xL1 efficiencies (%) L1 L0xL1 B->pp 60 34 Bs->DsK 56 29 Bs->J/y(ee)KS 44 21 Bs->J/y(mm)f 71 64 Bs->K*g 46 35 Trigger performance • fast (40MHz) • robust and flexible (does not rely on a single sub-detector) • triggers on many B decay topologies including hadronic and neutral final states preliminary ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  31. det :detection eff. (incl. geom. acc. in 4 and all material effects) • rec/det: reconstruction efficiency on detected events (track finding eff., neutral cluster rec.) • sel/rec: efficiency of offline selection cuts on reconstructed events (rejecting background) • trig/sel: combined L0+L1 efficiency on offline selected events (including pile-up veto rate reduction) • B/S from 10 million incl. bb back. Channel e tot Yield B/S B0 p+p- 0.71% 27 k <0.7 B0 K+ p- 0.96 % 139 k 0.10±0.03 Bs K+ K- 1.02 % 38 k <0.3 Bs Ds-p+ 0.31 % 87 k 0.55±0.15 Bs Ds-K+ 0.62 % 6.1 k<4.2 Bs J/y (m-m+ )f 1.67 % 100 k <0.3 166 k 0.61±0.09 B0  J/y (m-m+) KS 1.07 % B0 p 0.03 % 4 k <7 B0 K0* g 0.16 % 35 k <0.7 0.22 % Bs f  9.4 k <2.4 1 year = 2 fb -1 L = 2x1032 cm–2s-1 Event reconstruction and yields preliminary tot = edet* erec/det* esel/rec* etrig/sel= 12.2% * 91.6% * 19.6% * 32.6% = 0.71% ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  32. p+ p- B0 Knowledge of flavour at birth is essential for the majority of CP measurements B0 D K- l b Bs0 s b sources for wrong tags: Bd-Bd mixing (opposite side) b  c  l (lepton tag) conversions… s K+ u u εtag [%] ωtag [%] εeff [%] Combining tags Bdp p 41 35 4 Bs K K 48 33 6 Flavour tagging tagging strategy: • opposite side lepton tag ( b l) • opposite side kaon tag ( b  c  s ) (RICH, hadron trigger) • same side kaon tag (for Bs) • vertex charge tagging (for charged B) preliminary effective efficiency: eff= tag(1-2tag)2 ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  33. “gold-plated” decay channel at B-factories for measuring the Bd- Bd mixing phase • needed for extracting  from B   and Bs  K K, or from B  D* • in SM 0, non-vanishing value (0.01) could be a signal of Physics Beyond SM • precision measurement important  from B J/ Ks ( see talk by Jeroen Van Hunen) in 1 year: () ~0.6 B J/() Ks (untagged) in 1 year: expected signal events 166 k expected background 101 k ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  34. “gold-plated” decay channel for hadron machines, measuring the Bs- Bs mixing phase • in SM s= -2 = -22 expected to be (0.03) • large CP asymmetry would signal Physics Beyond SM • also needed for extracting  from B   and Bs  K K, or from Bs Ds K  from Bs  J/  ( see talk by Jeroen Van Hunen) J/  is not a pure CP eigenstate • 2 CP even, 1 CP odd amplitudes contributing • need to fit angular distributions of decay final states as function of proper time • requires very good proper time resolution M(KK)= 15 MeV/c2 = 38 fs in 1 year: s (dg) ~ 3.5o with input values: etag: 40% , wtag: 35% , Dms=20/ps t = 1.5 ps , DG/G = 0.1 , A = sin(-2dg) = 0.03 ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  35. Measure time-dependent CP asymmetries to extract and  from B    and Bs  K K ( see talk by Angelo Carbone) • relies on “U-spin” symmetry assumption (ds), which is the only source of theoretical uncertainty [R.Fleischer, Phys.Lett. B459, 306 (1999)] • determination of  and test of U-spin symmetry using measurements of  from Bs J/  and from B  J/ KS • sensitive to New Physics contribution by comparing withobtained from Ds K • hadron trigger • K/ separation • mass resolution (~18 MeV/c2) • proper-time resolution B0s KK B0  ~ 40 fs B0s KK ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  36.  from B    and Bs  K K input values sensitivity in 1 year BS K K B   ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  37. 1y 2y 3y 4y years 1 2 3 4 () 5.5 3.3 2.6 2.2  from B    and Bs  K K unique solution graphical solution in (d,)-plane • d = 2from B  J/ KSand s = 2 fromBs J/  • d,(d’,’)paramatrize P over T amplitude ratio of decay transitions in Bd  (Bs K+K-) • exact U-spin symmetry =>d =d’;=’ • 3 unknowns and 4 measurements 4 years 95% confidence region for d and  for =60 , d=d’=0.4 , =’=140 , d=51 , s=0 ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  38. 2 time dependent asymmetries from 4 decay rates: Bs (Bs)  D-sK+, D+sK- • only 2 tree-diagram-like topologies of same magnitude contribute • large interference effects expected [bc and bu diagrams (3)] • needs supression of (20) times higher Bs Ds background K or + Bs0 K+ Ds∓ 144 m  440 m 47m expected sensitivity in 1 year: () ~ 150 for Dms = 20 ps–1 () ~ 200 for Dms = 30 ps–1 - 2 from Bs  Ds K ( see talk by Richard White) important: hadron trigger, PID, proper-time resolution •  sensitivity depends on • relative amplitudes • strong phase difference • values of , ms,, s/s ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  39. g W b u,c,t s ( see talk by Galina Pakhlova) B0 K0* and Bs   In SM: • loop-suppressed bs transitions • BR( B0 K*0 ) = (4.30.4) 10-5 • expected direct CP violation <1% for B0 K*0  • expected CP violation in mixing ~0 for Bs   sensitive to New Physics m~ 64 MeV/c2  ~ 60 fs Preliminary study: • for BK 0* (ACP ) < 0.01 for one year LHCb • for Bs  sensitivity study ongoing B K  Bs KK  In one year expect triggered and reconstructed 35k eventsB0 K0* (K+p-) g ; S/B>1.4 9.4k events Bs (K+K+)  ; S/B>0.4 ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  40.  invariant mass resolution B0 K0*  ( see talk by Jose Helder Lopes) • BR( B0 K*0) = (1.20.4) 10-6 • within SM measure |Vts| • forward-backward asymmetry sensitive to New Physics, largely independent of hadronic uncertainties FBA angle between B momentum and +in the dilepton center-of-mass system FBA resolution In one year expect 4.4k eventsB0 K0*   triggered and reconstructed with S/B >0.45 Preliminary study: •  (ACP ) ~ 0.02 for one year LHCb • sensitivity study for AFB ongoing ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  41. precision measurement of mass, life-time • possible CP withBc  J/D, Bc  DsD, DD, ... • LHCb acceptance ~30% p (GeV) Preliminary study: s(ppBc) ~300 nb 109 Bc/ year Bc  J/y p (BR ~10-2) e ~ 3%18k events/year, S/B ~10 Background from B J/y X and prompt J/y reduced cutting on the distance between primary vertex and Bc vertex M( J/y(mm) p) GeV/c2 Bc mesons CDF: mBc= 6.4  0.4 GeV, tBc~ 0.5 ps ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  42. Present estimate of expected 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 preliminary channel parameters(1 year)depending onLHCb specific features Bd J/y KSb0.6for sin(2b)=0.79lepton trigger Bdp+ p-g~5.5U-spin summetryhadron trigger, RICH BsKKhadron trigger, RICH,  Bs Ds Kg ~15-20xs,DGs/Gs, dT1,T2hadron trigger, RICH,  Bs J/y dg ~3.5xs, CP+/CP-,d1,2lepton trigger,  Bs Ds pxs <75s>5hadron trigger, Bd K* mm4.4keventsmuon trigger,RICH Bd K* g 35keventsphoton trigger, RICH Bs    9.4k events photon trigger, RICH,   ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

  43. Summary and Conclusion • LHCb can study many different B-meson decay modes with high precision • particle identification capability • excellent mass and decay-time resolution • LHCb can fully exploit the large B-meson yields at LHC from the start-up • flexible, robust and efficient trigger • required luminosity of 2x1032 is low and locally tuneable • LHCb detector will be ready for data taking in 2007 at LHC start-up • detector production is on schedule • installation of magnet is ongoing • installation of detectors will start end of next year  Soon LHCb will offer an excellent opportunity to • determine precisely the CKM parameters through phase measurements • spot New Physics beyond the SM by overconstraining the Unitarity Triangles ADVANCED STUDIES INSTITUTE: PHYSICS AT LHC

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