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LHCb results

LHCb Collaboration: 755 M embers, from 55 Institutes in 15 Countries. LHCb results. Evgeny Gushchin (INR RAS) for the LHCb collaboration. Outline. Introduction LHC as B-factory LHCb is B-meson experiment for search NP in CPV and rare decays Experimental technique and key performances

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LHCb results

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  1. LHCb Collaboration: 755 Members, from 55 Institutes in 15 Countries LHCb results Evgeny Gushchin (INR RAS) for the LHCb collaboration

  2. Outline • Introduction • LHC as B-factory • LHCb is B-meson experiment for search NP in CPV and rare decays • Experimental technique and key performances • Physics program and selected Results • Conclusion XV Lomonosov conference, Moscow

  3. Search for New Physics beyond SM at LHC Search for new particles with observable masses produced directly in pp collisions AND/OR i.e. Higgs, Supersymmetry As virtual contribution of new heavy particles i.e. to loop and box diagrams in FCNC :i.e. it can change values, phases and/or Lorentz structure of couplings. • measurable as deviation from SM precise prediction for heavy quark processes, i.e. for B,D mesons: • in rare decays • in CP violation phase (mixing and decay) • Very good detector: • Selective/efficient trigger • PID • Excellent mass and time resolution • Very good statistics: • Very large bb-production LHCb @ LHC!!! XV Lomonosov conference, Moscow

  4. LHC as B - factory • Very high luminosity – 2.4*1033(nominal-1034)cm-2sec-1 • High production cross-section (@3.5TeV): • ~300µb ( pp  bb X) and ~6.1mb ( pp  cc X) • But also ~65 mb for minimum-bias • Annual yield (in LHCb) – > 1011BB-pair and 20xDD. Tevatron: instant luminosity reached ~4*1032/cm2/s and total L~11/fb. Cross-sections bb is 3 times lower than at LHC. In LHCb: ~1 of 200 collisions with b-quark ! ~1 of 10 - with c-quark ! All b-species: B+ : B0 : B0s : Λ0b : Bc 40%:40%:10%:10%:0.1% To reduce L0 rate > 10 MHz to 2-3 kHz VERY selective trigger is necessary! Trigger on low pT tracks with efficient PID B-pairs are produced mainly in forward and backward directions: Single-arm spectrometer covering ~4% of open angle has ~40% acceptance. XV Lomonosov conference, Moscow

  5. LHCb detector LHCb is forward spectrometer optimized for studies of CPV and B-meson rare decays LHCb key performances: Vertex/proper time resolution : VELO PID: RICH, Calorimeter, Muon system Mass resolution: Tracker ~4Tm p-p interaction point XV Lomonosov conference, Moscow

  6. LHCb detector and trigger efficiency HARDWARE PT PT PT SOFTWARE Detector subsystems are ~99% efficient! Trigger has very high selection efficiency! Muon trigger (J/) eff ~ 95% Hadron trigger (D0) eff ~ 60% XV Lomonosov conference, Moscow

  7. 1.638 ± 0.011 1.525 ± 0.009 1.525 ± 0.009 1.477 ± 0.046 1.391 ± 0.038 Vertex / Time resolution LHCb lifetime measurements using 36 pb-1 of 2010 data – world class! Both statistical and systematical errors are expected to be significantly improved with 2011 data! LHCb-CONF-2011-001 [ps] PDG [ps] Vertex Locator (VELO) provides excellent proper time resolution of ~50 fs XV Lomonosov conference, Moscow

  8. LHCb-CONF-2011-027: masses [MeV/c2] 5279.17 ± 0.29 5279.50 ± 0.30 5279.50 ± 0.30 5366.30 ± 0.60 5620.2 ± 1.6 6277 ± 6 Mass resolution Mass resolution is based on precise momentum measurement with LHCb magnet and tracker: Δp/p<0.5% up to 100 GeV/c With 2010 data! PDG [MeV/c2] World-best mass measurements! 11151±115 events =10.50±0.10 MeV/c2 816±30 events  = 6.96±0.25 MeV/c2 Bu+ J/ψ K+ Bs0 J/ψ φ 2010 L=35 pb-1 2010 L=35 pb-1 XV Lomonosov conference, Moscow

  9. Particle Identification photon/electron/hadron PID – SPD/PRS/ECAL/HCAL Muon PID – Muon system Hadron PID – RICH1 and RICH2 X 0 (no conversions) E= 7.2 MeV/c2 RICH PID absolutely necessary to identify charged hadrons in B  hh XV Lomonosov conference, Moscow

  10. LHCb operation LHCb collected ~37 pb-1 in 2010 and already ~ 700 pb-1 recorded in 2011 By end of 2011 LHCb hopes to collect 1 fb-1 • LHC reached nominal peak luminosity of 2.4*1033 cm-2s-1 with number of bunches is ~1300 from ~2600. • LHCb recording >1pb-1/hour running at • L~3.5*1032 cm-2sec-1 in auto-leveling mode • GPD luminosity is  4 times higher than LHCb LHC performs well! ~30 pb-1 for LHCb in 29 h in single fill ! dL/dt ~ 100 pb-1/week ! LHCb luminosity auto-leveling • Visual average number of vertexes per BX now is ~3 times larger than nominal µ =0.4 (in 2010 ~6 larger) • 1 PV gives ~30 tracks/rapidity unit • Higher µ means higher track multiplicity, that is dangerous for reconstruction 2010 2011 nominal µ =0.4 nominal µ =0.4 XV Lomonosov conference, Moscow

  11. LHCb physics program and key measurements LHCb is optimized for study of CP-violation and rare decays in B-mesons. LHCb physics program includes measurements: • CP-violation in B+,B0,Bs • Prospects for -angle measurement • Tree-level processes (B  DX), • Loop processes (charmless B decays) • Direct CP-violation (B  K) • Mixing induced CPV ( s) • Rare decays &NP • Bd → K*µµ • Bs → µµ • … • Quarkonia studies • Physics with charm • Soft QCD • Electroweak physics (W,Z) More studies are presented today in LHCb talks by Vladislav Balagura, Pavel Krokovny and Dasha Savrina Highlights in this talk      XV Lomonosov conference, Moscow

  12. -angle measurements • CKM – matrix is measured very precisely. • Great jobs done by B-factories and others. • Less constrained -angle : • combinated “trees” & “loops”:  = (67±4)° • from “trees” only:  = (73+22-25)° • Prospects for -measurementswith “trees”: • (based on Gronau-London-Wyler & Atwood-Dunietz-Soni methods • + time-dependent + Dalitz-plot analysis ) • To combine Bs Ds±K±, B0 DK*0 and B±DK± • ()~5° with 2 fb-1 • BsDs-K+ (Ds+K-) decays • under study, time-dependent analysis (Acp   - M) • M– Bs mixing phase well constrained in Bs→Ј/ψФ • - at first step ∆ms measurement using BsDs • B±DK± decays using common mode for D0&D0  K+- • Modemore suppressed for D0 and favored for D0 • maximizes interference: D0  K+- (DCS) and D0 K+- (CF) • But total branching very small (~10-7) • Preliminary: evidence for suppressed ADS mode at 4.0 with 343 pb-1. • Ratio to favored mode: “trees” PLB270,75(1991); PRL78,3257(1997) World-class measurement! World average (without LHCb): 1.6 ± 0.3 -0.58 ± 0.21 XV Lomonosov conference, Moscow

  13. Measurement of ∆ms World-class measurement! • ∆ms – mixing frequency in Bs • Used ~1381 B0s decays from 2010 data: • Combining the 4 decays allows suppress decay-specific features • To be used in time-dependent CPV studies Likelihood scan for ∆ms LHCb-CONF-2011-005, CERN-PAPER-2011-010 World average: ∆ms = 17.77 ± 0.10 ± 0.07 ps-1 XV Lomonosov conference, Moscow

  14. Direct CP asymmetry measurement in B0d,s→K LHCb with L=320pb-1 of 2011 data already has done: B0→K - the most precise single measurement and first 5σ observation at hadron machine! B0s→K - the first evidence of CP-violation in Bs decay! Raw asymmetry (has to be corrected for detector and production asymmetry) LHCb-CONF-2011-042 Acp(B0→Kπ) = -0.088±0.011(stat) ±0.008(syst) To be compared with world average: -0.098+0.012-0.011 Acp(Bs→Kπ) = 0.27±0.08(stat) ±0.02(syst) First LHCb result (with 37pb-1 data of 2010) LHCb-CONF-2011-011 Acp(B0→K+π־)= -0.074±0.033(stat) ±0.008(syst) Acp(B0s→K־π+)= -0.15±0.19(stat) ±0.02(syst) HFAG: Acp(B0→K+π־)= -0.098+0.012-0.011 CDF: Acp(B0s→K־π+)= 0.39±0.15(stat) ±0.08(syst) XV Lomonosov conference, Moscow

  15. LHCb result on fs/fd Very important for absolute branching measurements like Bs The ratio of fragmentation fractions fs/fd is measured by LHCb: • In hadronic decays, via relative abundance of B0s→D־s+ to B0→D־K+ and B0→D־+ LHCb-PAPER-2011-006, submit. To PRL • In semileptonic decays LHCb-CONF-2011-028 • And combined result LHCb-CONF-2011-034 XV Lomonosov conference, Moscow

  16. Quarkonium studies LHCb quarkonium physics program is rich and promising: • Heavy quarkonium states • give impact to theory (NRQCD..) • exotic states: molecular type state, tetraquark (?) • + Related production studies – test QCD models in forward region • Highlights : X(3872), X(4140), χc, χb • New exciting results are expected in future: • (2S) and (3S) production • J/ polarization (pT,y) • X(3872) quantum numbers and precise mass • Z±(4430) confirmation and Zb existence • New states? See also Vladislav’s talk today XV Lomonosov conference, Moscow

  17. Production studies at LHCb Many new results for flavour production were obtained with 2010 data: • pp  b b X • pp  J/ X • pp  F X W,Z • (1S) Bc+ • c • pp  J/ J/ X Test QCD model (tetraquark?) LHCb-PAPER-2011-007 LHCb-CONF-2011-012 LHCb-CONF-2011-016 LHCb-CONF-2011-017 Test QCD model in Forward region LHCb-CONF-2011-020 LHCb-PAPER-2011-013 first observation in p-p collisions XV Lomonosov conference, Moscow

  18. Mass measurement X(3872) (LHCb-CONF-2011-021) 2010 data MX(3872) = 3871.96 ± 0.46(stat) ± 0.10 (syst) MeV/c2 X(3872) production cross-section (LHCb-CONF-2011-043) To test molecular state mass precision has to be <0.1 MeV/c2 – in prompt. Quantum numbers have to be identified in B-decays. Search for X(4140) CDF observed a 5σ peak in the B+→J/ψ φ K+ channel. Candidate for exotic bounds state CDF arXiv:1101.6058 Preliminary (LHCb-CONF-2011-045) LHCb does not confirm presence of X(4140) LHCb with 376 pb-1: 364 ± 20 of B+→J/ψ φ K+ sample after φ –mass cut. ~3.2 times more than CDF with 6fb-1. Fit (LHCb): 7 ± 5 events Scaled from CDF data : 39 ± 9 ± 6 events X(3872) J/ +- Unknown quantum numbers. Not excluded conventional charmonium state c2(1D), but predicted mass is far bellow. Can be exotic state: molecular 1++ (D*D0 most popular) or tetraquark. XV Lomonosov conference, Moscow

  19. Production of χcJ/  • P-wave charmonium state • ECAL only detection of photons: with/without conversion • States separation is done by fit of mass-spectrum with both states χc1χc2 • 209k χc with 35.6 pb-1 (2010) LHCb-CONF-2011-020 Test NRQCD: colour singlet + colour octet Discrepancy at low pT Observation of b (1S)  • In order to interpret measurements of the  production and polarization the feeddown from higher bottomonium states has to beunderstood. • According to Pythia MC, ~ 40% of (1S) come from ­ b. • A clear signal for b production is seen. • The photon is reconstructed only with the calorimeter info. • Can not do a separation of the states yet. XV Lomonosov conference, Moscow

  20. CP-violation phase in Bs-mixing: Bs→Ј/ψФ • Dominant contribution – tree-level diagram • Contribution from “penguin” is small (10-3 – 10-4) • Interference between direct decay and decay via mixing gives CPV phase: s= M -2D • In Standard Model s  2 s = -2arg(VtsVtb*/VcsVcb*)  - 0.0363 ± 0.0017 rad • Search for New Physics in mixing: s= sSM+sNP See also Pavel’s talk today Expecting world best measurements s, Δms soon! Year 2011: Year 2010: Nsig=836 ± 60 LHCb-CONF-2011-006: data from 2010 L=36 pb-1 Standard Model value, probability = 22%(1.2σ) Results for 2011 data with much larger statistics are coming very soon -> expecting world best measurement of s! “Toy” Monte-Carlo using 2010 data as distribution function, but for 10xlarger statistics XV Lomonosov conference, Moscow

  21. Other channels relevant for s measurement “Penguin” diagram dominated can help to control penguin effect in Bs→Ј/ψФfor s extraction: • Bs→ФФ • Bs→K*K* - The first observation ! Can help to extractsand  • Bs→Ј/ψK* • Bs→K+K־- Most precise lifetime measurement ! Box diagram dominated can be used fors measurement: • Bs→Ј/ψf0(980) - The first observation !CP-odd eigenstate • Bs→Ј/ψf2’(1525) -The first observation ! LHCb-CONF-2011-019 LHCb-CONF-2011-025 LHCb-CONF-2011-018 Phys. Lett. B 698 (2011) 115 LHCb-CONF-2011-035 XV Lomonosov conference, Moscow

  22. Search for NP in rare decays:Bd → K*µµ See also Dasha’s talk today • The most known observable sensitive to NP is AFB • Current status: no evidence of zero-crossing point AFB(q2) predicted in SM • LHCb can reach precision for ZCP Δq2 < 0.5 GeV2 at 2 fb-1 LHCb with 309 pb-1achieved (preliminary) the most precise measurement to date LHCb-CONF-2011-038 Results are consistent with SM prediction for forward-backward asymmetry AFB, longitudinal polarization FL and differential brunching fraction dBF/dq2: Statistical errors are dominated now and will be improved with more data. Systematical error is also expected to be improved with more statistics. BaBar [PRD 79 (2009)], Belle [PRL 103 (2009)], CDF [PRL 106 (2011)] XV Lomonosov conference, Moscow

  23. Prospect:Bs,d → µµ Golden mode: Bs,d → µµ With ~300 pb-1 of LHCb data at SM level after selection: ~3.2 Bs → µµ and ~0.32 Bd → µµ events • Ultra rare decays (FCNC and helicity suppressed) • SM predicts (via box and penguin diagrams): BR(Bs → µµ) = (3.2 ± 0.2) · 10 -9 BR(Bd → µµ) = (1.1 ± 0.1) · 10 -10 CDF reported the observation: BR(Bs → µµ) = (1.8 +1.1-0.9) · 10 -8 arxiv: 1107.2304 Prospect on the base of 37 pb-1 (2010): • ~2 fb-1 will reach exclusion at SM level • Observation will need more statistics • LHCb presents preliminary result with 300 pb-1 • LHCb-CONF-2011-037: • BR(Bs0→ µµ) = 1.3 (1.6) · 10 -8 at 90%(95%)C.L. • BR(B0→ µµ) = 4.2 (5.2) · 10 -9 at 90%(95%)C.L. • Combining with preliminary result with 37 pb-1 • PLB 699(2011) 330,[hep-ex/1103.2165] • BR(Bs0→ µµ) = 1.2 (1.5) · 10 -8 at 90%(95%)C.L. • Combining with CMS observation • LHCb-CONF-2011-047: • BR(Bs0→ µµ) = 0.9 (1.1) · 10 -8 at 90%(95%)C.L. • Excess seen by CDF is not confirmed! Most-precise measurement! ~1 fb-1 allows a considerable constrain on MSSM XV Lomonosov conference, Moscow

  24. Conclusion • In 2010-2011 LHCb collected more than 700 pb-1 of rich data demonstrating: • Very good performance of trigger and data taking • Ability to work efficiently in hadronic environment • Ability to work with much larger luminosity than nominal (2 L -instant luminosity and 6 - PV av. number)! • With 2010 data LHCb already has got competitive results with B-factories and Tevatron • LHCb provided many world-class measurements: • First observations of many B-decay modes • Production of heavy flavour quarks and quarkonium states • World-best single measurement of direct CPV in B0s→K • World-class measurements of CPV phase s, ∆ms • Most precise measurements of rare decays Bd → K*µµ, Bs → µµ • Expecting ~1 fb-1 of data this year and many most-precise measurements very soon! • LHCb searches for New Physics with unprecedented precision! XV Lomonosov conference, Moscow

  25. Thank You! XV Lomonosov conference, Moscow

  26. BACK-UP XV Lomonosov conference, Moscow

  27. LHCb prospects for upgrade LHCb sensitivities for key observables CERN-LHCC-2011-001 XV Lomonosov conference, Moscow

  28. First observations of B-decays in LHCb • Bs  DK* LHCb-CONF-2011-008 • B  DK CS-mode, can be used for -measurements LHCb-CONF-2011-024 • B  (2s) LHCb-CONF-2011-014 – mixing CP • Bs J/K* penguin-suppressed LHCb-CONF-2011-025 • Bs K*barK* time-dependent CP LHCb-CONF-2011-019 • PLB 698(2011)14 • Bs J/ f0(980) mixing phasePLB 698(2011)115 • Bs J/ f2’(1525) mixing phase LHCb-CONF-2011-035 • Bc J/  first observation LHCb-CONF-2011-040 XV Lomonosov conference, Moscow

  29. Search for NP effects in Bd → K*µµ • In SM via FCNC (box and penguin diagrams) • Helicity structure is sensitive to right-handed and new scalar operators • The most known observable sensitive to NP is AFB • Current status: no evidence of zero-crossing point AFB(q2) predicted in SM • LHCb can reach precision for ZCP Δq2 < 0.5 GeV2 at 2 fb-1 XV Lomonosov conference, Moscow

  30. LHCb analysis and results Bd → K*µµ Analysis strategy: Events selection using Boosted Decision Tree (composition of topological and kinematical observables) Correction for non-uniformity of reconstruction and selection MC check with control channels Validation using Bd→Ј/ψK* Fit the angular observables LHCb with 309 pb-1achieved (preliminary) the most precise measurement to date BaBar [PRD 79 (2009)], Belle [PRL 103 (2009)], CDF [PRL 106 (2011)] Results are consistent with SM prediction for forward-backward asymmetry AFB, longitudinal polarization FL and differential brunching fraction dBF/dq2: Statistical errors are dominated now and will improved with more data. Systematical error is also expected to be improved with more statistics. XV Lomonosov conference, Moscow

  31. CP-violation in Bs mixing: Bs→Ј/ψФ See also Pavel’s talk today • Dominant contribution – tree-level diagram • Contribution from “penguin” is small (10-3 – 10-4) • Interference between direct decay and decay via mixing gives CPV phase: s= M -2D • In Standard Model s  2 s = -2arg(VtsVtb*/VcsVcb*)  - 0.0363 ± 0.0017 rad • Search New Physics in mixing: s= sSM+sNP • LHCb relevant results: • LHCb-CONF-2011-001: • Lifetime measurements of b →Ј/ψX • LHCb-CONF-2011-005: from Bs→Ds • Δms = 17.63 ± 0.11(stat) ± 0.04(syst) • Flavour tagging studies: • LHCb-CONF-2011-002: • Bs→Ј/ψФ: • Γs = (0.680 ± 0.034stat ± 0.027syst) ps-1 • ΔΓs = (0.084 ± 0.112stat ± 0.021syst) ps-1 • LHCb-CONF-2011-003: • Tagging efficiency measurements • LHCb-CONF-2011-004: • Time dependent analysis B0→Ј/ψKs DecayD MixingM • Strategy to measure s : • Trigger and select Bs→Ј/ψФ events • measure proper time • Measure transversity angles of final decay products to disentangle CP -odd and –even states • Tag initial flavor • Fit s with other unknown parameters XV Lomonosov conference, Moscow

  32. Expecting world best measurements s, Δms soon! CP-violation phase results: Bs→Ј/ψФ LHCb-CONF-2011-006: data from 2010 L=36 pb-1 Year 2011: Year 2010: Nsig=836 ± 60 Standard Model value, probability = 22%(1.2σ) Results for 2011 data with much larger statistics are coming very soon -> expecting world best measurement of s! “Toy” Monte-Carlo using 2010 data as distribution function, but for 10xlarger statistics XV Lomonosov conference, Moscow

  33. Rare decays: Bs,d → µµ • Ultra rare decays (FCNC and helicity suppressed) • SM predicts (via box and penguin diagrams): BR(Bs → µµ) = (3.2 ± 0.2) · 10 -9 BR(Bd → µµ) = (1.1 ± 0.1) · 10 -10 With ~300 pb-1 of LHCb data at SM level after selection: ~3.2 Bs → µµ and ~0.32 Bd → µµ events CDF reported the observation: BR(Bs → µµ) = (1.8 +1.1-0.9) · 10 -8 arxiv: 1107.2304 • LHCb presents preliminary result with 300 pb-1 • LHCb-CONF-2011-037: • BR(Bs0→ µµ) = 1.3 (1.6) · 10 -8 at 90%(95%)C.L. • BR(B0→ µµ) = 4.2 (5.2) · 10 -9 at 90%(95%)C.L. • Combining with preliminary result with 37 pb-1 • PLB 699(2011) 330,[hep-ex/1103.2165] • BR(Bs0→ µµ) = 1.2 (1.5) · 10 -8 at 90%(95%)C.L. • Combining with CMS observation • LHCb-CONF-2011-047: • BR(Bs0→ µµ) = 0.9 (1.1) · 10 -8 at 90%(95%)C.L. • Excess seen by CDF is not confirmed XV Lomonosov conference, Moscow

  34. Prospect: Bs,d → µµ Prospect on the base of 37 pb-1 (2010): ~2 fb-1 will reach exclusion at SM level Observation will need more statistics ~1 fb-1 allows a considerable constrain on MSSM XV Lomonosov conference, Moscow

  35. Other channels relevant for s • “Penguin” diagram dominated: Bs→ФФBs→K*K* Bs→Ј/ψK* Bs→K+K־ LHCb-CONF-2011-018 Most precise lifetime measurement of Bs→K+K־ Can be used to put constrains ons and ΔΓs LHCb-CONF-2011-019 The first observation of Bs→K*K* Can help to extractsand  LHCb-CONF-2011-025 Assuming all events are from K*→K for mass |M(K)-M(K*)|<150 MeV Can help to control penguin effect in Bs→Ј/ψФfor s extraction XV Lomonosov conference, Moscow

  36. Other channels sensitive for s • Box diagram dominated: Bs→Ј/ψf0(980) Bs→Ј/ψf2’(1525) CP odd eigenstate Phys. Lett. B 698 (2011) 115 The first observation of Bs→Ј/ψf0(980) Statistics of 2010 ~34 pb-1 LHCb-CONF-2011-035 Can be used fors measurement The first observation of Bs→Ј/ψf2’(1525) Statistics of 2010 ~34 pb-1+ 125 pb-1 of 2011 XV Lomonosov conference, Moscow

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