1 / 43

LHCb - The Future of Heavy Flavour Experiments

LHCb - The Future of Heavy Flavour Experiments. Beauty and Charm Decays: A Window on New Physics In honor of Sheldon Stone's 60th birthday May 20-21, 2006, Syracuse, NY. Franz Muheim University of Edinburgh. Outline. Physics Motivation UT triangles NP sensitivity

eitan
Download Presentation

LHCb - The Future of Heavy Flavour Experiments

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LHCb - The Future of Heavy Flavour Experiments Beauty and Charm Decays: A Window on New Physics In honor of Sheldon Stone's 60th birthdayMay 20-21, 2006, Syracuse, NY Franz Muheim University of Edinburgh

  2. Outline • Physics Motivation • UT triangles • NP sensitivity • LHCb experiment at LHC • B physics at Hadron Colliders • LHCb detector • Vertexing • RICH • Trigger • Status • Physics Programme • Bs oscillations and CP violation • CKM angle gamma • Rare decays • Sensitivities • LHCb Upgrade • Luminosity, Detector • Physics motivation • Conclusions F. Muheim

  3. Standard Model rho-eta fits • New Status including CDF Bs oscillation measurement - ms • Standard Model is very successful • 1.7discrepancy between Sin2 and Vub inclusive F. Muheim

  4. ? ? s s – Bs-Bsoscillations Motivation for Flavour Physics • Standard Model (SM) is a low-energy effective theory • Based on more fundamental theory manifest at a higher energy scale • Expect new particles and/or symmetries likely in the TeV region • How to probe New Physics (NP) ? • Discovery of new particles at energy frontier (LHC) • NP appears as virtual particles in loop processes leading to observable deviations from SM expectations in flavour physics and CP violation ( ) Supersymmetry New Physics Standard Model Bs  penguin decay F. Muheim

  5. P. Ball, Flavour in the LHC era workshop F. Muheim

  6. B-Physics at the LHC vs B-Factories F. Muheim

  7. Château Farges ATLAS Large Hadron Collider --- LHC Mont Blanc with a B-physics programme • LHCb dedicated for precision measurements of CP violation and rare decays in B hadrons • ATLAS/CMS optimized for high-pT discovery physics competitive for channels with leptons Lake Geneva F. Muheim

  8. n = # of pp interactions/crossing n=0 LHCb ATLAS/CMS n=1 Luminosities at LHC • LHC interaction points • 40 MHz pp interaction rate, bunch crossing every 25 ns • cross sectionsinel = 80 mb • Luminosity • Starting luminosity L = 1032 to 1033 cm-2s-1 • Design luminosityL = 103 cm-2s-1 • ATLAS/CMS • run at highest available luminosity • expect L<21033 cm–2s–1n < 5 for first 3 years • n = 25 at L=1034 cm–2s–1 • LHCb • Luminositytuneable by adjusting beam focus • run at L ~ 21032 cm–2s–1(max. 51032 cm–2s–1) • little pile-up (n = 0.5) • less radiation damage • Luminosity will be available for 1st physics run 10 fb–1 / year at low L 30 fb–1 total at low L 2 fb–1 / year 10 fb–1 in 5 years 1 year = 107 s F. Muheim

  9. Dipole magnet VELO ~1 cm B LHCb Experiment collision point Crucial for B physics: • optimised geometry and choice of luminosity • Trigger efficient in hadronic & leptonic modes • excellent tracking and Vertexing (m, ) • excellent particle ID - RICH F. Muheim

  10. 1 MHz (full detector readout) LHCb Trigger L0 efficiency 10 MHz (visible bunch crossings) Level-0 (Hardware) High pT - , , e, , hadron + pileup synchronized (40 MHz), 4 s latency HLT (PC farm ~2000 CPUs) Confirm Level-0 Associate tracks with minimum impact parameter and pT , e, h,  alleys Inclusive/exclusive selections ≤ 2 kHz (storage media) F. Muheim

  11. BsDs proper time resolution st ~ 40 fs VELO – Silicon Vertex Detector VELO – Silicon Vertex Detector • VELO – Vertex Locator • laid out as a series of R and Φsilicon detector stations • 0.8 cm to the beam line, situated inside beam vacuum vessel • Detached Vertex Trigger • Allows to select B-meson verticesHigh efficiency for all decay modes • Gives excellent proper time resolutionVital for resolving Bs oscillations F. Muheim

  12. Ring Imaging Cherenkov Detectors • Charged particle Identification • LHCb has 2 RICHdetectors with 3 radiators • Allows clean separation of different Bh+h modes • Not possible elsewhere at hadron colliders. Tevatron CDF data Bd signal BsKK signal Bd signal F. Muheim

  13. Installation Status Muon system Calorimeter ECAL, HCAL RICH2 Dipole Magnet RICH1 F. Muheim

  14. RICH Detectors RICH 2 RICH 1 RICH 2 RICH 1 HPDs F. Muheim

  15. LHC Status LHC tunnel • LHC start • July 2007 • 1st beam in late 2007 • Physics operation in 2008 LHC dipole Cryogenic servicesline F. Muheim

  16. a ~Vtd ~Vub* ~Vub* ~Vtd ~Vts g  g b • and g ~Vcb g-2 g LHCb Physics Programme Rare decays - very sensitive to NP • Radiative penguin e.g. Bd K* g, BsΦ g • Electroweak penguin e.g. Bd K*0m+m- • Gluonic penguin e.g. BsΦΦ, BdΦKs • Rare box diagram e.g. Bs m+m- B production , Bc , b-baryon physics Charm decays Tau Lepton flavour violation F. Muheim

  17. Bs Oscillations • Precision measurement of ms • is one of the first goals of LHCb physics programme • Expect 80k Bs Ds-p+ events per year (2 fb–1) with t ~ 40 fs • S/B ~ 3 derived from 107 fully simulated inclusive bb events  5 observation for ms < 68 ps–1 with 1 year/ 2 fb–1 ms< 40 ps–1 in ~1 month /0.25fb–1 Distribution of unmixed sample after 1 year (2 fb–1) assuming ms = 20 ps-1 CDF measurement F. Muheim

  18. fs and DGs from BsJ/ • CP Violation in Bs mesons • Interference between Bs mixing and decay • BsJ/ is the Bs counterpart of B0J/ KS • Bsweak mixing phase s is very small in SMs = –arg(Vts2) = -2 ≈ –22 ≈ –0.04 sensitive probe for New Physics • J/ final state contains two vectorsAngular analysis needed to separate CP-even and CP-odd amplitudesFit for sin s, s and CP-odd fraction (using external ms value) • sSensitivity • at ms = 20 ps–1 • Expect 125k BsJ/ signal events per 2 fb–1 (1 year) with S/Bbb > 3 • Expected precision (sin s) ~ 0.031 • Small improvement s by adding pure CP modes, e.g.J/, J/’, c • (sin s) ~ 0.013 for 10 fb-1 (first 5 years) ~3  evidence for s≈ –0.04 (SM) • Bs Lifetime difference s/s • Expected sensitivity (s/s) ~ 0.011 usingBsJ/ events • Similar sensitivity in untagged semileptonicBsDs-l+ eventsExpect 700k events per 2 fb–1 F. Muheim

  19. With RICH g from Bs DsK • Two tree decays(bc and bu) of O(3) • Interference via Bs mixing • Weak phase of Vub = e-ig for bu diagram • Theoretically clean • Insensitive to New Physics • Large background~20 • from Cabibbo allowed decay • need RICH, residual background ~10% • Expect 5.4 k events in 1 year • S/Bbb > 1 at 90% CL Vub Vcb F. Muheim

  20. Both DsK asymmetries (after 5 years, ms = 20 ps–1) Ds–K+: info on  + ( + s) Ds+K–: info on  – ( + s) g from Bs DsK • Fit the 4 tagged time-dependent rates: • Extract  + s, strong phase difference , amplitude ratio • Bs Ds  events used in fitto constrain other parameters (mistag rate, ms, s …) • Sensitivity for g • s(g) ~ 14in 2 fb-1or 1 yearfor ms = 20 ps–1 • Precision statistically limited • 8-fold ambiguity can be resolved ( 2-fold) if s large enough, or using B0  D together with U-spin symmetry (Fleischer) F. Muheim

  21. B   (95% CL) p/K p/K Bd/s d Bd/s p/K p/K Bs KK(95% CL) g()  from B and BsKK • Measure time-dependent CP asymmetry • Adir and Amix depend onCKM angle, mixing phasesd and s, and ratio of penguin-to-tree amplitudes (d ei) • U-spin symmetry (d s) • Assume d=dKK and =KK • 4 measurements and 3 unknowns (, d and )usingdfrom Bd-> J/ KS and sfromBs-> J/f) • Extract angle  • LHCb sensitivities • Event yields - 1 year data set, 2fb-126k B and 37k BsKK • Precision - () ~ 5 R. Fleischer, PLB 459 (1999) 306 • Sensitive to New Physics in penguins • Uncertainty from U-spin assumption F. Muheim

  22. A1 = A(B0 D0K*0): bc transition, phase 0 A2 = A(B0 D0K*0): bu transition, phase + A3 = 2 A(B0 DCPK*0) = A1+A2, because DCP=(D0+D0)/2 g from B0 D0K*0 • Dunietz variant of Gronau-London-Wyler method (GLW) • Two colour-suppressed diagrams with |A2|/|A1| ~ 0.4 interfering via D0 mixing • Measure 6 decay rates (self-tagged + time-integrated): • LHCb expectations for 2 fb–1 (=65, =0) Sensitivity () ~ 8in 2 fb-1 F. Muheim

  23.  from B±  DK± • Two interfering tree processes in charged B decay • Decays common to D0 and D0 • Interference effects depend on 3 parameters– b→u , b→c interferencerB – the amplitude ratio betweend two diagrams (0.1 – 0.2)δB – a CP conserving strong phase difference • i) Cabbibo favoured self-conjugate D decays e.g. D0 Ks, KsKK, KKππDalitz analysis Sensitivity () ~ 5 in 2 fb-1 • ii) Cabbibo favoured/doubly Cabbibo suppressed D decayse.g. D0 K, KADS method Colour allowed Colour suppressed F. Muheim

  24.  from B±  DK± ADS method • based on Atwood-Dunietz-Soni [Phys. Rev. Lett. 78, 3257 (1997)] • Measure relative rates of B–  DK– and B+  DK • Two interfering tree B-diagrams, one colour-suppressed (rB ~0.15) • Two interfering tree D-diagrams, one Doubly Cabibbo-suppressed (rDKp ~0.06) • Self-tagging – advantageous for LHCb • No proper time measurement required • 3 observables, 4 rates, but only 3 ratios 5 parameters (g, dB, dDKp, rB, rDKp) rDKpknown • Sensitivity • () ~ 5 in 2 fb-1 Events per 2 fb-1 F. Muheim

  25. s, s, Bs,d→μ+μ- at LHC • Very rare FCNC decay • in SM low uncertainty • BR(Bs→μ+μ-) = (3.5 ± 0.9)  10–9 • BR(Bd→μ+μ-) = (1.0 ± 0.5)  10–10 • Very sensitive to New Physics: • Large enhancement in Higgs mediated SUSY processes • Decay is one of the most sensitive SUSY probes • Complementary to direct SUSY searches at LHC F. Muheim

  26. M0 [GeV] 1 year Bs+ – signal (SM) b, bbackground Inclusive bb background Mass resolution LHCb 2 fb–1 17 < 100 < 7500 18 MeV/c2 ATLAS 10 fb–1 7 < 20 75 MeV/c2 CMS (1999) 10 fb–1 7 < 1 48 MeV/c2 Excluded! Bs,d→μ+μ- at LHC • New Physics Sensitivity • For BR at SM value M0, M½ > 1500 GeV • Competitive with direct searches • Current Results • dominated by Tevatron • New limit from CDF&D0 at FPCP 2006BR(Bs→μ+μ-) < 8 10-8 @ 90% CL • LHC expectations • Will observe decay down to SM level • LHCb will face competition from ATLAS/CMS F. Muheim

  27. Rare FCNC decay Inclusive branching fraction well known in SM BR(B→Xsμ+μ-) = (1.59 ± 0.11)  10–6 Exclusive decays better at LHCb Di-lepton invariant mass s BR - well controlled in region outside resonances -J/ and ’ Bd→K*0μ+μ- • Forward-backward asymmetry AFB(s) • Asymmetry angle - B flight direction wrt + direction in +- rest-frame • Sensitive probe of New Physics • Deviations from SM by SUSY, graviton exchanges, extra dimensions • AFB(s0) = 0 - predicted at LO without hadronic uncertainties • Zero points0 and integral at high ssensitive to Wilson coefficients AFB(s) for B0K*0+- BR(s) for B0K*0+- F. Muheim

  28. Expected Signal Yield 4400 events in 1 year/2fb-1 Background/Signal Full simulation, 11 M b-bbar MC B/S ~ 0.2 – 2.6 AFB zero point sensitivity s0 = 4.0±1.2 GeV2in 1 year s0 = 4.0±0.5 GeV2 in 5 years 13% error on C7eff/C9eff AFB in Bd→K*0μ+μ- AFB after 5 years AFB after 1 year F. Muheim

  29. Sensitivity Summary Sensitivity Comparison ~2013 LHCb 10 fb-1 vs Super-B factory 5 ab-1 • Based on 10 fb-1 • Bs mesons • Precision measurements • Oscillations(ms,) < 0.01 ps-1 • CP violation (s) ~ 0.013 • Lifetime difference • stat(s/s) < 0.01 • CKM angle  • Reduce error on  by factor 5 ( ) ~ 30 in best mode • Bs→Ds+K- • B0→D0K*0 • B+→D0K+ ADS, Dalitz • Rare Decays • AFB in Bd→K*μ+μ- • Bs→μ+μ- • B→K*, Bs→  • Charm Physics • CP violation • D0 oscillations • Under study • Lepton Flavour Violation • B and D, e.g. B,D→μe, μ • Tau decays, e.g. + →μ+μ-μ+ Bs Common No IP Neutrals,  LHCb andB-factoriesare complementary F. Muheim

  30. LHCb Upgrade • LHCb Operation • Increase luminosity adjabatically to ℒ ~ 5 x1032 cm-2s-1 • LHCb detector can cope, could/should be done anyway • Upgrade LHCb to run at 10 times nominal Luminosity • ℒ ~ 2 x1033 cm-2s-1 • Multiple interactions per beam crossing increases to n ~ 4 • Does not require LHC luminosity upgrade (SLHC) • Detector Considerations • to operate LHCb above5 x1032 cm-2s-1 • Vertex detector (VELO) requires replacing after 6 to 8 fb-1 • Existing Front-End electronics limits L0 Trigger output to 1.1 MHz • Muon (Hadron) L0 trigger does (does not) scale with luminosity • LHCb Upgrade Ideas • Replace VELO with a radiation tolerant vertex detector Strips and/or pixels, remove RF foil (closer to beam  5mm) • Improve trigger by adding first level displaced triggerImplementation in FPGAs • Replace inner most region of RICH photo detectors • Increase/decrease size of Inner/Outer Tracker • Replace inner most region of ECAL with crystal calorimeter • Replace all Front-End electronics with 40 MHz read-out • Initial studies to operate LHCb at 2 x1033 cm-2s-1 after 2011 have started F. Muheim

  31. Physics Case for LHCb Upgrade Sensitivity Comparison ~2020 LHCb 100 fb-1 vs Super-B factory 50 ab-1 • 100 fb-1 data sample • run 5 yrs at ℒ ~ 2 x1033 cm-2s-1 • Estimates scaled with luminosity • trigger improvements not included • CP Violation in Bs Mesons • SM prediction s = -0.040 • s precision statistically limited • to 3 evidence with 10 fb-1 • ~10 measuement with 100 fb-1 • b->s transitions • Very sensitive to New Physics • 2.6 discrepancy in average ofS(b->s) = sind -sin2 • Best b->s penguin mode for LHCb • Bs→  • Expected yield 1.2 k events per 2 fb-1 • If you measure S() ≠ s (SM)clear signal for New Physics • S() precision statistically limited • With 100 fb-1estimate S() = 0.040 • Similar precision for Bd→ KS Bs Common No IP Neutrals,  LHCb andSuper-B factoryare complementary F. Muheim

  32. Conclusions • Heavy Flavour Physics in 2006 • The CKM mechanism is very successful in describing the data • New Physics will manifest itself as corrections to the SM • Require precision measurements to over-constrain UT triangles • LHCb experiment • Will exploit the large rates of B-mesons at the LHC • Construction of LHCb detector and accelerator well underway • Will be ready for physics in 2007 • LHCb physics programme • Exploit the Bs systemPrecision measurements of Bs mass and lifetime difference Measure CP violation in Bs mesons • Reduce error on CKM angle by a factor 5 • Probe New Physics in rare B meson decayswith electroweak, radiative and hadronic penguin modes • Hopefully find the unexpected F. Muheim

  33. Backup Slides F. Muheim

  34. Heavy Quark Flavour Structure Table from G. Isidori F. Muheim

  35. LHC Experiments LHCb with a B-physics programme • LHCb dedicated for precision measurements of CP violation and rare decays in B hadrons may be the only B-physics experiment running after the B factories unless new projects (Super-B, LHCb upgrade) are approved • ATLAS/CMS optimized for high-pT discovery physics competitive for channels with leptons CMS ATLAS F. Muheim

  36. b-b angular correlation 100mb 230mb b Production at the LHC PT vs pseudo-rapidity • Momentum pB and decay length L • larger in forward region • <pB> ~ 100 GeV/c • Mean B meson flight path <L> ~10 mm sB F. Muheim

  37. Flavour Tagging • LHCb • Most powerful tags - opposite kaon, bcs, (Bd) and same side kaon (Bs) • Combined D2 ~ 7.5% (Bs) or ~ 4.5% (B0) • Neural network approach leads to ~9% and 5% • Comparison • CDF/D0 achieved ~1.5%/2.5% (Bd) and ~4% (Bs ) • B factories achieved ~ 30% F. Muheim

  38. sin(2) with B0J/ KS • CPV in interference of mixing and decay • Measure time dependent CP asymmetry • 1st Analysis for LHCb • Test proper timereconstruction • Test tagging performance • Using control channelse.g B+  J/K+ and B0  J/K*0 • Dependent on how event is triggered - on signal or on rest of the event • Sensitivity • Expect ~240k signal events/year stat(sin(2)) ~ 0.02 • Can also push further the search for direct CP violation in term  cos(mdt) F. Muheim

  39. m2(0–) +– 00 –+ m2(0+) Combined discriminant variable Angle from Bd 0–+ decays • Dalitz plot analysis (Quinn Snyder method) • Bd0–+ selection based on multivariate analysis • Use resolved and merged 0 • Expect 14k events per year, B(bb)/S < 1 • Toy MC study: • 11-parameter likelihood fits performed in time-dependent Dalitz space • B/S = 0.8 (flat and resonant bkg) gen=106° 1 year () ~10° F. Muheim

  40. Additional Observables • Angular correlations • 3 angles l,K* and  • 4-dim decay amplitude • Transversity amplitudes • A┴,A║,A0 for full description • Sensitive to left and right-handed currents • Expect large effectsfor New Physics Kruger&Matias hep-ph/0502060 F. Muheim

  41.  from B±  DK± ADS method • based on Atwood-Dunietz-Soni [Phys. Rev. Lett. 78, 3257 (1997)] • Measure relative rates of B–  DK– and B+  DK • Two interfering tree B-diagrams, one colour-suppressed (rB ~0.15) • Two interfering tree D-diagrams, one Doubly Cabibbo-suppressed (rDKp ~0.06) • Self-tagging, i.e. good for LHCb • No proper time measurement required • Event yields 30k, 1k, 30k, 1k in 2 fb-1 • 3 observables, 4 rates, but only 3 ratios 5 parameters (g, dB, dDKp, rB, rDKp) rDKpknown • Sensitivity • () ~ 5in 2 fb-1 F. Muheim

  42. B → Xs μ+μ- • FCNC diagrams • Well known SM BR BR(B→Xsμ+μ-) = (1.59 ± 0.11)  10–6 • Observables • Branching fraction BR • Forward-backward asymmetryAFB • Sensitive to New Physics • Deviations from SM by SUSY, graviton exchanges, extra dimensions ... • At hadron colliders • Inclusive decays are difficult to access preferred by theory • Exclusive decays affected by hadronic uncertainties • Channels under study • Bd→K*0μ+μ- • B+→K+μ+μ- • Λb→Λμ+μ- • Bs→μ+μ- F. Muheim

  43. LHCb Sensitivities with 2 fb-1 F. Muheim

More Related