1. B Physics at the LHC 1 Ulrich Uwer Heidelberg University Flavor Physics in the LHC Era Singapore, November 2010 b s Disclaimer: Due to time-constraints only LHCb

2. Quark Flavor Mixing 2 http://ckmfitter.in2p3.fr/ Within uncertainties, flavor changing data described by SM: There are several 2…3  tensions! New Physics effects only appear as corrections to leading SM terms.

3. “New Physics” in B-decays 3 bs u, c, t bs X Y bq q bW bq X q bY  Precision measurement of loop-suppressed effects: very high statistic and access to unexplored B s system Standard Model New Physics + + W

4. LHCb Search Strategies for NP 4 Explore FCNC transitions with large sensitivity to NP, especially b  s transitions (poorly constrained by current data) B s mixing phase  s Penguin and other rare decays: B s , B 0  K * , B s   but also CP violation in D decays Improve CKM elements and challenge the SM by over- constraints: Precise determination of angle  Compare tree versus loop results measurements w/ NP discovery potential Precision CKM metrology Slide by U.Egede

5. Outline 5 LHCb experiment Detector performance Results on flavor production Towards a measurement of  Exploring the B s sector Rare FCNC processes

6. B Production at LHC 6 bb bb  Cross sections predictions (PYTHIA)  s = 7, 10, 14 TeV  B ±, B 0, B s, B c,  b … (40% 40% 10% 10% from LEP)  20x larger charm production  Design L ~ 2 x 10 32 cm -2 s -1 (tuned) ~ 10 12 bb events / year (2 fb -1 ) 15 kHz bb-events in LHCb  inel ~ ( 0.89, 0.95, 1 )  80 mb  bb ~ ( 0.44, 0.67, 1)  ~500  b ~250  b bb Production p p b b Gluon-Gluon-Fusion: bb

7. Key requirements for b Physics at LHC 7 b Hadron BsBs -- K-K- ++ -- -- ++ K-K- K-K- 7 mm Excellent vertex resolution: to resolve fast B s oscillation. Background reduction:Very good mass resolution Good particle identification (K/  ) High statistics:Efficient trigger for hadronic and leptonic states t = /  c  t  40 fs

8. LHCb Detector 8 Muon System  /h separation Trigger Calorimeter h/e/  / separation Trigger Tracking-System RICH Detectors p/K/  Vertex Detextor

9. LHC Operation 9 Peak lumi ~2  10 32 cm -2 s -1 Delivered int. lumi: O(50 pb -1 ) Bunches/colliding: 368/344 Commissioning of 50 ns spacing Preparation for bunch trains End Aug Excellent performance: 3.5 TeV + 3.5 TeV 2010 lumi goals reached: Heavy Ion run since ~1 week Expect >1 fb -1 in 2011 March 30th

10. LHCb Data-taking 10 LHCb: Recorded: 37.7 pb -1 (eff.~90%) Design lumi w/ only 344*) bunches:  Large pileup, very busy events *) nominal: 2800 bunches Peak Lumi = 1.7  10 32 cm -2 s -1 Interactions / crossing

11. Typical Event at =2.5 11

12. First B candidate (single interaction) 12 First B + → J/ψ (μ + μ – ) K +

13. Vertex resolution 13 6 cm Both Velo halves move at every fill: nominal position of sensor: 8 mm to beam axis! Impact parameter resolution (x): Primary vertex resolution:  x  15  m  y  15  m  z  76  m Module and sensor alignment better than 5  m. Fill-to-fill variations < 5  m.

14. Tracking 14 LHCb Preliminary OT LHCb Preliminary TT

15. Mass resolution 15 m = 3094.5 MeV  = 14 MeV m = 5277 MeV  = 13 MeV  = 9 MeV (w/ mass constr) B +  J/  K + J/    Resolutions still slightly different from prediction: calibration and alignment ongoing. K s →  m = 497.2 MeV  = 3.3 MeV

16. PID with RICH 16 D + →KK  D s →KK  124 nb -1 D + →K  124 nb -1 PID allows separation of topologically identical finals states

17. Muon Identification 17 Tracking system Muon system J/  µ probe µ tag   > 90% and mis-ID rate 10 GeV/c Mis-ID rate: K s   KK

18. Heavy Flavor Production 18 B + → J/ψ (μ + μ – ) K +

19. Inclusive J/  production 19 Inclusive J/  production:  (2.5<y<4,p T <10 GeV/c)=7.65 ± 0.19 ± 1.10 +0.87 -1.27  b J/  production from b: f b = (11.1 ± 0.8) %  (2.5<y<4,p T <10 GeV/c)= 0.81 ± 0.06 ± 0.13  b σ(pp  H b X; 2<η b < 6) = 84.5 ± 6.3 ± 15.6 μb polarization uncertainty Not well described by colour singlet nor by octet models. Phythia LHCb ICHEP 2010 (preliminary) LHCb ICHEP 2010

20. bb cross section from B  D 0 (K  )  X 20 D from B Prompt D Fake D  (pp→H b X; 2 <  < 6) = 75.3  5.3  13.0 μb ηLHCb preliminaryTheory 1Theory2 2-677.4 ± 4.0 ±11.4 μb8970 all292 ± 15 ± 43 μb332254 Average of two measurements Theory 1: Nason, Dawson, Ellis Theory 2: Nason, Frixione, Mangano and Ridolfi LHCb assumed ~250 μb LHCb: PL B 694 (2010) 209. B  D(K  )  X LHCb ICHEP 2010 12 nb -1

21. Prospects for semi-leptonic decays 21 Fake D D from B B s  D s µX Same technique to reconstruct b  D +,D s,  c  X  b   c µX (  c  pK  ) (D s  KK  ) Allows semi-leptonic measurements: e.g. b-hadron fragmentation fractions 800 nb -1  c from B

22. Open Charm Production 22 Impact parameter used to separate prompt from secondary charm

23. Charm Cross Section 23 preliminary! e.g. D 0  K -  + Slide by Z.Yang

24. Spectroscopy 24 X(3872) J/        (1S)  (2S)  (3S)  (2S)

25. CKM Angle  25 http://ckmfitter.in2p3.fr/ A lot of pioneering work by B-factories Constraints from direct measurements still weak

26. Towards a  measurement at LHCb 26 ADS: D 0 decays suppressed (K +  - ) GLW: D 0 decays to CP state ( ,KK) GGSZ: D 0 decays to K s  (Dalitz) BB f K  D 0 K  V ub Tree Level Processes 1 fb -1 Combined sensitivity: CDF (5 fb -1 ): ~30 evts ~300 nb -1 B +  (K  )  +

27. B  hh 27 ~3 pb -1 B d   B s  KK B d/s  /K B d/s Loop Processes R.Fleischer Measure time dependent CP asymmetries (direct, mixing) in B d   and B s  KK. ~3 pb -1

28. B 0  K  28 3 pb -1 (World average: A CP ( B  K  ) = -0.098  0.012)

29. B s Sector – Mixing phase  s 29 SM p-value is 44% ~6500 events CDF public note 10206 bs s b  m s, , phase  s

30. B s  J/   30 observed yield: ~40 B s  J/  events / pb -1 B s  J/  candidate Mixture of CP even/odd final states: Angular analysis to separate CP states ~17 pb -1 ~670 evts

31. Flavor Tagging 31 Expected Tagging performance: Uncalibrated tagging algorithms applied to B 0  D*  (D 0   )  + evts : ~60% of expected performance. Calibration & tuning ongoing.  m= 0.53 ± 0.08  10 12 s -1 1.9 pb -1 opposite side same side (simulation) tagging power  stat. weight  D 2 = 6.2% (MC)

32. Control Channels 32 B +  J/  K + B 0  J/  K* 0 Tagging calibration (opposite side) Kinematically similar to B s  J/  Angular acceptance checks: Polarization amplitudes Check of tagging performance ~17 pb -1

33. Expected Sensitivity 33 35k selected evts / 1 fb -1 (based on measured  bb ) = 38 fs Tagging:  D 2 =6.2% S/B as in simulation MC 2010

34. Semi-leptonic asymmetries a sl 34 Evidence of anomalous CP-violation in mixing of neutral B mesons by D0. Inclusive method at LHCb difficult due to the production asymmetry in pp collisions (~10 -2 ) and detection asymmetries. A. Lenz, U. Nierste, 2007 SM: ~10 -4  X X  + X B0B0 B0B0 B0B0 B0B0 CP PRD 82, 032001 (2010)

35. Prospects at LHCb 35 Time dependent asymmetry difference of semi-leptonic B decays: B s + →D s (KK  )μ and B 0 →D + (KK  )μ : (cancels detection asymmetries and allows simultaneous fit of prod. asymmetry) LHCb Method: a sl (B s ) - a sl (B d ) ~0.6 pb -1 stat. only

36. Penguin and very rare FCNC decays 36 b  s  penguins B d  K*  Very rare FCNC proc. B d,s  

37. B 0  K*  37 Standard Model Corresponding Wilson coefficients C i describe short-range physics. New Physics in Wilson coefficients C i = C i SM + C i NP or new operators. Effective Theory Operator Product Expansion

38. New Physics Sensitivity 38 Observables:  l,  K, , m 2  A FB (q 2 ) ~ - Re  C 10 eff * [ C 7 eff +  (q 2 ) C 9 eff ]   forward-backward asymmetry: q2q2 High sensitivity of angular observables CDF: 100 evts CDF Public note 10047 BELLE: 250 evts PRL 103 (2009) 171801. BABAR:100 evts PRD 79 (2009)031102 A FB (q 2 ) for B 0  K*  ~450 evts

39. Prospects 39 LHCb expectation for 1 fb -1 ~1400 events w/ B/S~0.25 140 events for 100 pb -1 B 0  J/  K* for selection efficiency and background studies: Just 0.1 fb -1 will give equivalent error to B-factory measurement.

40. Very Rare Decays - B d,s  Large NP contributions possible SM: BR(B s  μ + μ - )= (3.6±0.3)x10 -9 BR(B d  μ + μ - )= (1.1±0.1)x10 -10 A. Buras (2009) CDF Public note 9892 arXiv:1006.3469

41. LHCb Prospects for B d  41 LHCb strategy: 3 discriminants Invariant mass Geometrical likelihood Muon likelihood

42. Conclusion & Outlook 42 LHC and the LHC(b) experiment(s) perform amazingly well. LHCb has recorded ~40 pb -1 of high-quality data in 2010 First competitive B-physics results for Moriond 2011: B s mixing, mixing phase  s, limit on B s , D results For 2011 expect 1 fb -1 (minimum) of data:  results for all LHCb key measurements. Flavor Physics at the LHC has started

43. Backup 43

44. Semileptonic Asymmetries 44 S. Hansmann

45. Semileptonic Asymmetries 45 S. Hansmann

46. Production ratio D + / D s + 46  (D + ) /  (D s + ) = 2.32  0.27  0.26 Consistent with PDG: f(c  D + ) / f(c  D s + ) = 3.08  0.70 preliminary!

47. Charm – Mixing and CPV 47 D*  D(K  )  s 124 nb -1 ~17k evts

48. Comparison with “high-p t ” Detectors 48 ATLAS/CMS: |  | < 2.5 LHCb: 2<  < 5 ATLAS/CMS: Optimized for high-p t signatures very restricted particle ID B-physics limited to muon triggers, large p t (>4…6 GeV) Small bandwidth by T.Skwarnicki

49. Mass resolution 49 ATLASCMSLHCb σ ( J/  ) 70 MeV47 MeV14 MeV σ (  ) 170 MeV100 MeV47 MeV

50. Impact parameter resolution 50 @2GeVATLASCMSLHCb σ (IP) 60 µm50 µm25 µm

51. B s  51 Expected results (assuming σ(pp → bbX) = 500 µb) @14TeV: –Uncertainty coming from limited amount of MC –B → J/  K is used for normalization to translate the signal cross section to a BR N sigN bkg90% CL ATLAS (10 fb -1 )5.614--- CMS (1 fb -1 )2.46.5<1.6 10 -8 with 10 – 20 fb -1 SM prediction region 3σ evidence after 3 years@10 33 5σ observation after 1 years@10 34 with 10 – 20 fb -1 SM prediction region 3σ evidence after 3 years@10 33 5σ observation after 1 years@10 34 2.1 10 -8 * * Scaling quoted result by ratio of LHCb measured x-sec at √s = 7 TeV to 14 TeV value assumed in MC study. CMS Prel. N sig = 48 σ M = 32 MeV/c 2 MC 280 nb -1 P.Perrret, HQL 2010

52. J/  from B 52