1. 1 Heavy Quarks at the Tevatron CDF DO Bottom Barbro Åsman Stockholm University For the CDF and D 0 Collaborations TOP Proton LISHEP 06 Rio de Janeiro

2. 2 Golden Eggs Mixing: B s, B d New particles: X(3872), Xb, Pentaquarks, … Mass measurements: B c,  b, B s, … Production properties:  (b),  (J/y), … B and D Branching ratios Rare decay searches: B s -> µ+µ-, D 0 -> µ+µ-, … CP Violation Lifetimes: ,  b, B s, B c.. SURPRISES!?

3. 3 HOW ? Measuring  b ( udb ) Lifetime L xy PV c  L xy M B P T bb   p   p p B0B0 K0K0  WHY ? A ~2  Differance between theory and experiment for  (  b )/  (B 0 ). Theory = 0.86 ± 0.05 xy-plane

4. 4  b Lifetime Extract lifetime with unbinned likelihood fit to proper decay length and mass event information.  (  b )=1.45 + 0.14 – 0.13 ± 0.02 (sys) ps  b )/  (B 0 ) = 0.944 ± 0.089  (  b )=1.22 + 0.22 – 0.18 ± 0.04 (sys) ps  b )/  (B 0 ) = 0.87 +0.17 -0.14 ± 0.03

5. 5 B c Contains Two Heavy Quarks Unique system with two heavy quarks of different flavor Probes heavy-quark theories in the region between the cc and bb Decays in 3 different ways: b or c decays or bc annihilation Low production rate B +,B 0 : 40%, B s,B baryons: 10%, B c ~.05% Reconstruct B c  J/  e

6. 6 Results  (B c ) = 0.474 + 0.073 – 0.066 ± 0.033 (sys) ps  B c ) = 0.448 +0.123 – 0.096 ± 0.121 (sys) ps  BcBc L xy XY - plane  e c  L xy M B * K P T (vis) Where K = P T(vis) / P T (B) is given from MC

7. 7 Review of B 0 System In the B 0 system: physical mass eigenstates = flavor eigenstates   where:  =  H -  L (lifetime difference)  = (  H +  L )/2   m = m H - m L (mass difference) B L = B 0 + B 0 B H = B 0 - B 0 Time evolution of the two states is governed by the time- dependent Schrödinger equation and in the limit   m Prob (B 0 -> B 0 ) = ½ e -  t (1+cos  mt) Prob (B 0 -> B 0 ) = ½ e -  t (1-cos  mt) oscillation frequency (  m d,  m s ) Ignoring CP violation

8. 8 Extract  from B s  K + K - lifetime Measurement of B s -> K + K - lifetime (=  L ) in 360 pb -1 Mass fit and lifetime fit: Extraction of  (CP)/  (CP): This measurement gives c  L = 458 ± 24 ± 6 µm HFAG average gives weighted average: (  L 2 +  H 2 ) /(  L +  H ) Extract  H Thus derive  =-0.080 ± 0.23 (stat) ±0.03 (syst)

9. 9 B S lifetime and  B s 0 -> J/    = 1.53 ± 0.08 +0.01 -0.04 ps  = 0.15 ± 0.10 +0.03 -0.04 ps Gives rise to both CP-even and CP-odd final states

10. 10 Summary of 

11. 11 B d and B s Mixing W W b d(s) t V tb V td(s) t b    m d = (lots of QCD) x V td  m s = (lots of QCD) x V ts  m s /  m d = (much less QCD ) x V ts / V td V ud V us V ub V cd V cs V cb V td V ts V tb V = V ud V ub * + V cd V cb * + V td V tb * = 0 V td V tb * V cd V cb * V ud V ub * V cd V cb * - 1 = V td V ts

12. 12 Analysis Strategy B s oscillations is more difficult than B d oscillations because of the fast mixing frequency In order to measure  m:  Reconstruct the B s signal  Know the flavor of the meson at its production time (Flavor tagging) and get  D 2 (tagging power)  Calculate Proper length resolution S = signal events  D 2 = tagging pow er S/B = signal/background  t = proper time resolution

13. 13 Reconstruction Currently only using semileptonic decay of the B s B s -> D s  X (D s ->       μD ± : 7,422±281 μD s : 26,710±560 μD ± : 1,519±96 μD s : 5,601±102

14. 14 Flavor Tagging Soft lepton Soft Lepton Tagging (  or e ): Charge of the leptons together with the jet charge gives the flavor of b Jet Charge Tagging : Sign of the weighted average charge of opposite B jet gives the flavor of b  DsDs BsBs b-hadron Jet Charge P.V. Tagging Side Vertexing Side Secondary Vertex Charge

15. 15 Cross Check of Tagging On a B d sample  D 2 = (2.48 0 ±.21 +0.08 -0.06 ) % Tagger tuned using B d mixing measurement  m d = 0.506 ± 0.020 ± 0.014 ps -1 B0B0 B+B+ )()( )()( )( tNtN tNtN tA osc no osc no     

16. 16 B s Lifetime  DsDs BsBs XY plane L xy c  L xy M B *K P T (lD) Where K = P T (lD) / P T (B) is given from MC

17. 17 Amplitude Fit Method Prob (B 0 -> B 0 ) = ½ e -  t (1+Acos  mt) Fit to data – A free parameter Prob (B 0 -> B 0 ) = ½ e -  t (1-Acos  mt) Fit for oscillations amplitude A for a given  m Expect A = 1 for frequency = true  m s Expect A = 0 for frequency = true  m s If no signal observed : Exclude  m s value at 95% C.L. In region where A+1.65  A < 1 Sensitivity at 95% C.L. is at  m s value for which 1.65  A =1 BdBd BsBs

18. 18 B s Mixing Limit  m s > 14.8 ps -1 @ 95% CL Uppgrade to an event by event fit

19. 19 Log Likelihood Scan  m s < 21 ps -1 @ 90% CL Most probable value of  m s = 19 ps -1 With the assumption A = 1

20. 20 Top pp t t b b W l q q Branching Ratios Production Cross Section Top Mass Top Charge Top Lifetime W Rare/non SM Decays W Helicity Resonance Production Top

21. 21 TOP PAIR PRODUCTION ~85%~15% q t t q t t Standard model pair production via the strong interaction Discovered in Run I  = 6.77 ± 0.42 pb for m top = 175 GeV

22. 22 TOP DECAY 20% 14.6% 1.2%2.4% 46% 1.2% DILEPTON [ ee, mm, em,+ 2 b jets ] Small BR ~ 5% Smallest background LEPTON + JETS [ e, m + 4 jets (2 b jets) ] Large BR ~ 30% Moderate background ALL HADRON [ 6 jets (2 b jets) ] Large BR ~ 46% Larges background

23. 23 DILEPTON CROSS SECTION Signal Selection : 2 high P T Leptons 2 high P T Jets Large missing E T Veto invariant mass = Z Background : Physics (from MC) : Z /g * → , Dibosons Instrumental (from Data): Faked Missing E T and Faked Leptons

24. 24 DILEPTONS  8.3 ± 1.5(stat) ± 1.0(syst) ± 0.5(lumi) pb  8.6. +2.3 -2.0 (stat) +1.2 -1.0 (syst) pb Results (Topological cuts): ee,  and e  combined CDF 750 pb -1 preliminary D0 350 pb -1 preliminary Result (b-tag): lepton + Track/b-tagging  7.1 +2.6 -2.2 (stat) ± 1.3 (syst) pb D0 350 pb -1 preliminary Combined with e  topological)  8.6 +1.9 -1.7 (stat) ± 1.3 (syst) pb Primary Vertex Secondary Vertex Displaced Tracks Promt Tracks L xy d0d0

25. 25 Lepton+Jets Cross Section Backgrounds  Physics : W+Jets  Instrumental: QCD Multijet Signal Selection  1 high P T Leptons  4 high P T Jets (2 b-jets)  Missing E T Topological /Kinematics Analyses  6.7 +1.4 -1.3 (stat) +0.9 -0.8 (syst) pb  6.0± 0.6 (stat) ±0.9 (syst) pb Likelihood Discriminant Neural Network

26. 26 Lepton+Jets Cross Section Secondary Vertex Tag  8.2± 0.9 (stat) +0.9 -0.8 (syst) pb  8.2± 0.6 (stat) ±1.0 (syst) pb

27. 27 Summary of Cross Section

28. 28 t-channel Single Top q q' W t b u d b t W t b q s-channel Top production via the Weak Current SM :  pb ± 8%  = 1.98 pb ± 8% A lot of background : W + jets, ttbar etc

29. 29 Selecting Single Top b S channel: - W - High P T lepton - Missing E T -2 b – jets - At least 1 b-tagged jet T channel: - W - High P T lepton - Missing E T -2 b – jets - At least 1 b-tagged jet - 1 extra jet t W b l p p q

30. 30 Single Top Search Likelihood Discriminant Method Separate Single top from Backgrounds Dzero limits with 370 pb -1 95% C.L.:  s < 5.0 pb  t < 4.4 pb CDF limits with 695 pb -1 95% C.L.:  s < 3.2. pb  t < 3.1 pb

31. 31 Top Mass Measurement

32. 32 Why Interesting? Top mass is fundamentel parameter Top mass can constrain the Higgs mass trough the loop diagrams: WW WW b t H Top mass can probe new physics

33. 33 jet e/μe/μ b-tag jet jet b-tag jet jet Hard to Measure Complicated events – 12 ways to interpret 4 jets Reconstruction of jet energy scale is distorted by: additional interactions electronic noise pileup from previous buch-crossing energy deposition outside jet cone different response for different particles 20% of b-jets have muon and neutrino Background contamination lepton

34. 34 Top Mass Methodology TEMPLATES One mass per event from kinematic fit. Create templates using event simulated with different M top values + background. Perform maximum likelihood fit to extract final mass. MATRIX ELEMENT Build likelihood directly from PDFs, matrix element(s), and transfer functions that connect quarks and jets. Integrate over unmeasured quantities Calibrate measured mass and error using simulation.

35. 35 CDF Template Method Four samples with different S/B and sensitivity to top:  0 b-tag 4 jets > 21 GeV  1 b-tag 3 jets > 15 GeV, 4 th : 8 GeV < Et < 15 GeV  1 b-tag 4 jets > 15 GeV  2 b-tag 3 jets > 15 GeV, 4 th > 8 >GeV -Use assignments with lowest χ 2 to reconstruct top mass. - top masses equal -reconstructed W near M W Reconstructed W mass to calibrate JES

36. 36 CDF Result 173.4+-2.5(stat+JES)+-1.3(syst).

37. 37 D0 Matrix Element Method  x: reconstructed lepton and jets kinematics  JES from M W constraint.  Signal and background probabilities: from differential cross-sections  All events are combined in a likelihood -ln L(m top ;JES)=-lnΠ P evt (x i ;m top ;JES) Maximal use of information in each event: Calculating event-by-event probability to be signal or background, based on the respective matrix elements: P evt (x;m top ; JES) = f top *P sgn (x;m top ; JES) + (1-f top ) * P bkg (x;JES) M top = 170.6 ± 4.4 (stat.) ± 1.7 (syst.) GeV/c 2 JES = 1.03 ± 0.03

38. 38 Top Mass in Dilepton Events Pros: Fewer combinations Cons: Unconstrained kinematics: 2 neutrinos in final state Small branching fraction (5%) CDF: 700 pb -1 164.5 ± 4.5 (stat.) ± 3.1 (syst.) GeV/c 2 D0: 370 pb -1 177 ± 11 (stat.) ± 4 (syst.) GeV/c 2

39. 39 Top Mass Result

40. 40 Are the other Properties of the Top Quark as Expected? Top Charge W-t-b

41. 41 Top Charge t b W l +2/3 -1/3 +1 0 t b W l -4/3 -1/3 0 Standard Model Exotic 4 th Generation Assiciate lepton + b-jet to a top quark Kinematic fit for the ttbar hypothesis Determine charge of the b-jet P T weighted sum of tracks in the b-jet Analys method

42. 42 Top Charge II D0 RunII (365pb -1 ) - 17 candidate events with two tagged b-jets, lepton, missing E T, 4 jets or more. - two entries per event for top and anti-top. - discriminate b and b with jet charge algorithm - calibrate Monte Carlo with data using two jet heavy flavor sample with opposite jet tagged with  charge. - excluded the hypothesis of an exotic quark with charge = -4/3 e at 95% confidence level.

43. 43 With top quark samples we can measure it directly as “R”: The relative rates of ttbar events with 0/1/2 b-tags is very sensitive to R Top Decay Properties We said t  Wb, but really 100%? Indirect measurement using the CKM matrix: implies |V tb | is 0.998 @ 90% CL R = 1.03 +0.19 -0.17 (stat + syst) R > 0.64 @ 95% CL V tb > 0.80 @ 95% CL R = 1.12 +0.27 -0.23 (stat + syst) R > 0.61 @ 95% CL V tb > 0.78 @ 95% CL

44. 44 Conclusion Lots of Exciting Results are pouring out from CDF and DO! What I have shown is just the Top of the iceberg And there are much more in the pipeline Look forward to many more exciting results soon!