B-physics at the TeVatron

Transcription

1 B-physics at the TeVatron Michael J. Morello University and INFN of Pisa for the CDF and DØD collaboration V Workshop Italiano sulla Fisica pp ad LHC January 30 th February 2 nd, 2008, Perugia (Italy) 1

2 Outline Introduction Tevatron, CDF and DØ detectors B Physics at hadron colliders In this talk B 0 s mixing: measurement of m s. Lifetime, lifetime difference Γ and CP violation in neutral B 0 s system Untagged and tagged analysis of B 0 s J/Ψφ. Λ 0 b Lifetime. Charm mixing. BR and A CP of B 0 /B 0 s h+ h - and Λ 0 b pπ(k) decays. γ from B + D 0 CP K+ and B 0 s D s K. Ξ b Baryon (First Observation) FCNC: B 0 s µµ Conclusions. List of topics not covered. 2

3 Fermilab Tevatron pp collisions at 1.96 TeV 2.5 fb 1 good data on tape (results today 1-2fb1 1 ) 1.7MHz collision rate (396 ns bunch spacing) Peak luminosity 2.92x10 32 cm 2 s 1 Average ~5-6 6 pp interactions per bunch crossing Anticipate luminosity as high as 3x10 32 cm 2 s 1 Challenging for the detector, trigger and event reconstruction 3

4 CDF detector Central tracking includes silicon vertex detector surrounded by drift chamber p T resolution dp T /p T = p T GeV -1 excellent mass resolution ~14 MeV for J/ψصµ, ~22 MeV for BØhh good vertex resolution ~100 fs Particle identification: de/dx (1.5σ p>2gev) and ToF Good electron and muon identification by calorimeters and muon chambers. TIME OF FLIGHT 4

5 DØ Detector Excellent coverage of Tracking and Muon Systems Excellent calorimetry and electron ID 2T Solenoid, polarity reversed weekly High efficiency muon trigger with muon p T measurement at Level1 by toroids SMT H-disks SMT F-disks SMT barrels 5

6 B Physics at the Tevatron Mechanisms for b production in pp collisions at 1.96 TeV g b g b b g b b g b Flavor Creation (gluon fusion) q b g Gluon Splitting g q Flavor Excitation q q b Flavor Creation (annihilation) At Tevatron,, large b production cross section Tevatron experiments CDF and DØD enjoy rich B Physics program Plethora of states accessible: B 0 s, B c, Λ 0 b, Ξ b, Σ b complement the B factories physics program Total inelastic cross section at Tevatron is ~1000 larger that b cross section large backgrounds suppressed by triggers that target specific decays. d 6

7 B Triggers J/ψ Dimuon Displaced Track p T (µ)>1.5gev J/ψ mass requirement Opposite charge p T (µ)>1.5 or 2 GeV Triggers with/without charge requirement p T (track)>2 GeV IP(track)>80 or 120 µm Opposite charge µ J/ψ µ π+ µ B + K + µ B 0 J/ψ K 0* B + J/ψ K + Λ b J/ψ Λ B c J/ψ π B 0 s J/ψ φ Ξ b, B** B µµ+hadrons B µµ bb µµ cc µµ B D s π B D s K B hh Λ ph D Kπ 7

8 MATTER Bound states: b b s s 0 0 B s B s ANTIMATTER B 0 s Physics b occurs 0 via B s s Matter antimatter: V ts u, c, t,? V ts * W + W - u,c,t,? NEW PHYSICS? s 0 B s b The mass eigenstates (H and L) are superpositions of B 0 s and B 0 s System characterized by 4 parameters (no CPV ñ φ s =0): masses: m H, m L lifetimes: Γ H, Γ L (Γ=1/τ) CPV ñ φ s 0 then Γ s = Γ 12 cos(φ s ), φ s expected very small in SM. m s has been measured very precisely. Γ s and φ s so far measured imprecisely. 8

9 B 0 s mixing: m s m s consistent with Standard Model expectation. New Physics can alter the weak phase φ s of the mixing amplitude. The same New Physics phase would also be visible through Γ s < Γ s (SM) m s = ± 0.10 (stat) ± 0.07(syst) ps -1 (>5σ) PRL 97, (2006) [hep-ex/ ] 9

10 B s Lifetime in B 0 s J/ψφ Decays Most precise B s lifetime measurements from B s J/ΨΦ decays CDF ~2500 signal events in ~1.7 fb -1 DØ ~900 signal events in ~1.1 fb -1 [arxiv: hep-ex] τ s =1.52 ± 0.04 (stat) ± 0.02 (syst) ps (world best measurement) [Phys. Rev. Lett. 98, (2007)] 1.52 ± 0.08(stat) (syst) ps 10

11 Width Difference Γ s CP-even (B s light ) and CP-odd (B s heavy ) components have different lifetimes Γ 0 [arxiv: hep-ex] [Phys. Rev. Lett. 98, (2007)] Γ s = 0.08 ± 0.06 (stat) ± 0.01 (syst) ps -1 (world best measurement) Γ s = (stat) ± 0.02 (syst) ps-1 Cross check: CDF measures decay amplitudes and strong phases in high statistics B 0 J/Ψ K *0 sample agreement and competitive with B factories 11

12 β s in Un-tagged B 0 s J/ψφ Decays Without identification of the initial B s flavor still have sensitivity to β s. Symmetries in the likelihood 4 solutions are possible in 2β s - Γ plane Due to irregular likelihood and biases in fit, CDF only quotes confidence regions and p-value: Standard Model probability 22%. DØ quotes point estimate (solution closest to the SM prediction and fit biases included in the systematics): φ s = ± 0.56 (stat) (syst). CDF: 90%, 95% C.L DØ: 39% C.L. 12

13 Flavor Tagging at CDF Quarks produced in pairs at Tevatron. Tag either b quark which produces B 0 s J/ψφ (SST), or other b quark Opposite Side (OST). Effective tagging power: ε = efficiency of taggers D = diluition =1 2w (w = mistag prob.) εd 2 = figure of merit Jet Charge: the sum of charges of the b-jet tracks correlated to the b-flavour Soft Lepton (e,µ) due to b lνx l charge correlated to b-flavour ε = 96 ± 1 % D =11 ± 2 % εd 2 ~ 1.2 % Same Side Kaon: for B 0 s is likely to have close in R a K + from fragmentation ε = 50 ± 1 % D=27 ± 4 % εd 2 ~ 3.6 % 13

14 β s in Tagged B 0 s J/ψφ Decays (CDF) CDF Run II Preliminary L = 1.7 fb -1 flavor tagging Assuming the SM predicted values for 2β s =0.04 and Γ s =0.096 ps -1 the p-value corresponding to our data is 15% (compatible at 1.5σ). Confidence regions procedure without external constraints: 2βs s in [0.32, 2.82] at the 68% C.L. 0 π Confidence regions with external constraints on strong phases, lifetime l and Γ s = / : 2βs s in [0.40, 1.20] at 68% C.L. 0 π Available β s parameter space is greatly reduced when using flavor tagging. 2β s 2β s 14

15 Future sensitivity for β s at CDF projection Data Today 1.35 fb -1 Pseudo-experiments 6 fb -1 generated with β s =0.02 Projected Confidence Regions in 6 fb -1 assuming same yield per fb -1 in future and same tagging efficiency and dilution. 15

16 Charge Asymmetry in Semileptonic B 0 s µd s X Decays Study with L = 1.3 fb -1 with total signal yield ~27K events Compare decay rates of B s and B s : Suppressed systematic uncertainties do to regular change of magnet polarization at DØ. Semileptonic charge asymmetry is related to Can combine this result with β s measurement in B s J/ψφ to constrain NP 16

17 Combined DØ Constraints on B 0 s Width Difference and CP Violation Phase Combine width difference and CP violation phase from time dependent angular analysis B 0 s J/ψφ with measurements from charge asymmetry in semileptonic decays Contours indicate 39% C.L. regions: Final combined DØ results with ~1 fb -1 : From tagged B s J/ψφ analysis, CDF excludes ~half available space in φ s - Γ s plane. Based on flavor SU(3) symmetry, CDF constrains strong phases to B factories measurements bottom left solution is suppressed as well. Expect tagged B 0 s J/ψφ analysis from DØ soon Expect updated analyses with 2x data from both experiments soon 17

18 Λ 0 b Lifetime Important test of models that describe quark interactions between heavy and light quarks within bound states HQET + Lattice QCD predicts: DØ measures Λ b lifetime two decay modes: 1.2 fb -1, ~170 signal events 1.3 fb -1, ~4400 signal events 18

19 Λ 0 b Lifetime Current Status DØ measurements are in agreement with the theoretical predictions and with the world average CDF measurement in is ~3σ high w.r.t world average Expect CDF measurement in hadronic mode soon decay mode CDF lifetime (ps), 1 fb -1 DØ lifetime (ps), 1.3 fb -1 x expected soon x 19

20 Charm Mixing Charm mixing small in Standard model Mixing in Bottom and Strange systems larger due to top participating in box diagram Sign of new physics if mixing oscillation different from expected B factories have presented evidence of charm mixing D 0 Kπ/KK/ππ. Large charm samples in CDF data D* - D 0 π soft, D 0 Kπ π soft charge tags D flavour at production RS: D* - D 0 π soft WS: D 0 mixed or DCS decay RS WS WS/RS ratio: 20 20

21 Charm Mixing at CDF 1.5 fb -1 Perform binned fits to ratio of WS to RS as function of time of D 0 decay Probability of no mixing is 0.13% (Equivalent to 3.8σ significance) Allowed regions of charm mixing parameter phase space: [arxiv: hep-ex]

22 B µµ in the Standard Model In Standard Model FCNC decay B µµheavily suppressed Standard Model predicts: BR( BR( B s B d + 9 µ µ ) = (3.4 ± 0.5) 10 + µ µ ) = (1.00 ± 0.14) 10 [A. Buras Phys. Lett. B 566,115] 10 B d µµfurther suppressed by CKM coupling (V td /V ts )2 Below sensitivity of Tevatron experiments SUSY scenarios (MSSM,RPV,mSUGRA) boost the BR by up to 100x Observe no events set limits on new physics Observe events clear evidence for new physics 22

23 Aim to measure BR or set limit: BR( B s total + NBs αb+ εb+ fu µ µ ) = BR( B J / ψk ) BR( J / ψ µ µ ) total N α ε f B+ Methodology Bs Bs Use B + J/ψK + as a control mode Neural network selection Use particle ID to suppress B hh, fake muon backgrounds Measure remaining background Measure acceptance and efficiency ratios s In case of observation CDF mass resolution allows to separate B 0 from B 0 s. 23

24 Results on B µ + µ 2 fb -1 No significant excess, set limits: BR(B 0 s µµ) < %CL < %CL BR(B 0 s µµ) < %CL < %CL We are here BR(B 0 d µµ) < %CL < %CL? Best existing limits Combined Tevatron limit (unofficial) BR(B 0 s µµ) < %CL (13x SM) 24

25 Tevatron sensitivity to B 0 s µ+ µ - Expectations from analysis performed on previous analysis (780 pb - 1 ), this is not a projection. BR(B 0 s µµ) < with 8 fb - 1. Corresponding to 6xSM. Corresponding to 2 SM events reconstructed Conservative: in the past measurements were better than predictions. Today CDF sensitivity (with 2 fb - 1 ) is equal to the previous la sensitivity estimated for CDF+D0 Possible further improvements of the analysis: binned unbinned analysis (a( a la B hh) FNAL directorate plan is to run through CDF-only, today Integrated Lumi/experiment (fb -1 ) Total 25

26 Direct A CP (B 0 K + π - ) 1 fb -1 Loose cuts B 0 yields comparable to e + e ± 84 B 0 K + π - Large B 0 s K + K - sample [hep-ex/ ] Discrepancy with A CP (B + K + π 0 ) up to 4.9 σ. 3.5 σ Goal with Full Run II statistics 1% 26

27 B 0 s K- π + 1 fb -1 Tight cuts New signals Selection optimized to observe and limit setting of B 0 s K - π + First observation of three rare charmless decays: B 0 s K - π +, Λ 0 b pπ - and Λ 0 b pk - 11σ ~7000 events 8σtotal 6σ [hep-ex/ ] B 0 s Kπ yield = 230 ± 34(stat.) ± 16(syst.) Probability Ratio (PR) for data and projection shows the good separation achieved between B 0 s K- π + and the rest (backgrounds and other signals) (mass, mometa and de/dx of both tracks) 27

28 Direct A CP (B 0 s K- π + ) 1 fb -1 It is different from 0 by 2.3σ (stat. + syst.). First measurement of DCPV in the B 0 s K - π +. Our measurement favors large CP violation as expected in the SM. On the other hand it is also compatible with 0 due to the large uncertainty. Unique opportunity of checking for the SM origin of direct CP violation. Proposed by Gronau [Phys.Rev. B482, 71(2000)], later shown to hold under much weaker assumptions by Lipkin [Phys. Lett. B621,126, (2005)]. (SM =-1) Very interesting to pursue with more data, in any case! 28

29 BR and A CP in Λ b pπ(k) 1 fb -1 First study of CP asymmetry in b baryon decays (SM prediction ~10%) Use large sample collected by two displaced track trigger along with B hh. Additionally, first branching fractions relative to B 0 Kπ decays: Minimal Supersymmetric Extensions of SM violating the R-parity could both suppress A CP and enhance by factors ~100 BR with respect to SM predictions. [PRD63,056006(2001)] 29

30 BR and A CP of B + D 0 CP K+ 1 fb -1 Motivation: theorethically clean Measurement of CKM angle γ via GLW (Gronau-London-Wyler) method [PLB253,483 and PLB265,172] Method: Unbinned kinematics+de/dx fit, simultaneous of modes B + D 0 K + with D 0 CP K+ K - /π + π -, D 0 flav π+ K -. B + D 0 K + [π + K - ]K + B + D 0 K + [K + K - ]K + B + D 0 K + [π + π - ]K + ~516 ~103 ~26 30

31 BR and A CP of B + D 0 CP K+ 1 fb -1 K + K - K + K - A CP sin γ 3σ 4σ A first at a hadron collider. 1fb -1 same precision of e + e - Next step is to combine with Atwood-Dunietz-Soni (ADS) method to extract γ [PRD 63, and PRL 78,3257]. 31

32 B 0 s D s K mode Final states of both sign are accessible by both B 0 s and antib 0 s mesons with similar size amplitude ( λ 3 ) [Phys. C54,653 (1992) Nucl.Phys.B659: ,2003] CP violation due to mixing can occur from the mixed and unmixed interference paths Need time-dependent CP asymmetries measurement Interesting comparison: B 0 s D s K can be suppressed or enhanced compared with B 0 DK First step: observation and BR measurement. Untagged lifetime of B 0 s D s K may resolve the sign ambiguity in sen(2β s ) recent paper Ø [arxiv: hep-ph] 32

33 1.2 fb -1 BR(B 0 s D s K) First observation Combined mass and PID maximum likelihood fit on 1.2 fb -1 M D sπ (B0 s D s X [φπ]x) de/dx for the B-daughter track Important features: Accurate study of physics background components from MC: B 0 s D(*) s X,D s ρ etc. FSR tail from B 0 s D s π(nγ) Main systematics from dedx templates 5.26<M<5.35 GeV/c σ Yield 109 ±19 B 0 s D s K events 33

34 Ξ b Baryon (First Observation) The third observed b baryon after Λ 0 b and CDF s recent discovery of Σ b Study b baryons great way to test QCD which predicts M(Λ b ) < M(Ξ b ) < M(Σ b ) Predicted mass: ± 8.1 MeV Discovery decay mode at DØ: x z cτ ~ 0.1 cm cτ 5 cm cτ 8 cm 34

35 Clear excess in Ξ b invariant mass distribution Significance ~5.5σ Number of signal events: 15.2 ± 4.4(stat) (syst) Mass: ± 0.011(stat) ± 0.015(syst) GeV ( prediction ± 8.1 MeV) Width: ± GeV in good agreement with MC expectation GeV Production relative to Λ b J/Ψ Λ Ξ b Mass Measurement where f(b X) : fraction of times b quark hadronizes to X 35

36 Ξ b Mass Measurement most precise measurement at 7.8σ significance 36

37 Conclusions Very rich B physics program at the Tevatron Great Tevatron performance accumulate data fast and expect ~6 fb -1 by the end of the run. Expect updates of many analyses. Exciting time to study CP violation and search for new phenomena in B physics at Tevatron! 37

38 Topics not covered Charge asymmetry in semileptonic B 0 s decays, first observation of Σ b, B 0 s D s (*) D s (*), CP asymmetry in B + J/ψK +, Ψ(2S) production, Y(1S), Y(2S) polarization, B 0 J/ψ K* 0 angular analysis, orbitally excited B mesons, b-b correlations, B c mass and lifetime.. and many others. 38

39 Backup 39

40 m s 17 < m s < 21 ps -1 at the 90% C.L PRL (2006) [hep-ex/ ] 40

41 B 0 s mixing: m s m s = ± 0.10 (stat) ± 0.07(syst) ps -1 (>5σ) 17 < m s < 21 ps -1 at the 90% C.L PRL 97, (2006) [hep-ex/ ] PRL (2006) [hep-ex/ ] 41

42 Lifetime: B 0 s J/ψφ Extremely physics rich decay mode Can measure lifetime, decay width, and, using known m s, CP violating phase β s The decay of B s (spin 0) to J/Ψ(spin 1) Φ(spin 1) leads to three different angular momentum final states: L = 0 (s-wave), 2 (d-wave) CP even L = 1 (p-wave) CP odd three decay angles ρ = (θ,φ,ψ) describe directions of final decay products 42

43 B 0 s J/ψφ Phenomenology Three angular momentum states form a basis for the final state Use alternative transversity basis in which the vector meson polarizations w.r.t. direction of motion are either: - longitudinal (0) CP even - transverse ( parallel to each other) CP even - transverse ( perpendicular to each other) CP odd Corresponding decay amplitudes: A 0, A, A At good approximation, mass eigenstates and are CP eigenstates use angular information to separate heavy and light states determine decay width difference Γ = Γ L Γ H some sensitivity to CP violation phase β s Determine B s flavor at production (flavor tagging) improve sensitivity to CP violation phase β s 43

44 B 0 s J/ψφ Formulogy B s decay rate as function of time, decay angles and initial B s flavor: time dependence terms angular dependence terms terms with β s dependence terms with m s dependence due to initial state flavor tagging strong phases: 44

45 CP Violation Phase β s in Un-tagged B 0 s J/ψφ Decays Without identification of the initial B s flavor still have sensitivity to β s Due to irregular likelihood and biases in fit, CDF only quotes Feldman-Cousins confidence regions (Standard Model probability 22%) DØ quotes point estimate: Φ s = ± 0.56 (stat) (syst) Symmetries in the likelihood 4 solutions are possible in 2β s - Γ plane CDF: 90%, 95% C.L DØ: 39% C.L. 45

46 CP Violation Phase β s in Tagged B 0 s J/ψφ Decays Likelihood expression predicts better sensitivity to β s but still double minima due to symmetry: Study expected effect of tagging using pseudo-experiments Improvement of parameter resolution is small due to limited tagging power (εd 2 ~ 4.5% compared to B factories ~30%) However, β s -β s no longer a symmetry 4-fold ambiguity reduced to 2-fold ambiguity allowed region for β s is reduced to half β s - Γ likelihood profile 2 log(l) = 2.3 ~ 68% CL 2 log(l) = 6.0 ~ 95% CL un-tagged tagged β s (rad) 46

47 CP Violation Phase β s in Tagged B 0 s J/ψφ Decays First tagged analysis of B 0 s J/ψφ (1.4 fb-1 ). Signal B s yield ~2000 events with S/B ~ 1. As in un-tagged analysis, irregular likelihood does not allow quoting point estimate. Quote Feldman-Cousins confidence regions. strong phases can separate the two minima symmetry axes Standard Model probability 15% ~1.5σ > 0 < 0 Confidence regions are underestimated when using 2 logl = 2.3 (6.0) to approximate 68% (95%) C.L. regions 47

48 β s in Tagged B 0 s J/ψφ Decays with External Constraints (CDF) Spectator model of B mesons suggests that B s and B 0 have similar lifetimes and strong phases Likelihood profiles with external constraints from B factories: constrain strong phases: constrain lifetime and strong phases: External constraints on strong phases remove residual 2-fold ambiguity 48

49 β s in Tagged B 0 s J/ψφ Decays Final Results (CDF) 1D Feldman-Cousins procedure without external constraints: 2β s in [0.32, 2.82] at the 68% C.L. 0 π 2β s 1D Feldman-Cousins with external constraints on strong phases, lifetime and Γ = 0.096±0.039: 2β s in [0.40, 1.20] at 68% C.L. 0 π 2β s Available β s parameter space is greatly reduced when using flavor tagging: CDF Run II Preliminary L = 1.7 fb -1 flavor tagging DØ results on β s using flavor tagging expected soon. 49

50 Charge Asymmetry in Semileptonic B 0 s µd s X Decays (DØ, 1.3 fb -1 ) Study with L = 1.3 fb -1 with total signal yield ~27K events Compare decay rates of B s and B s : Suppressed systematic uncertainties do to regular change of magnet polarization at DØ. Semileptonic charge asymmetry is related to In SM Φ s is predicted to be very small NP can significantly modify SM prediction If dominates Can combine this result with β s measurement in B s J/ΨΦ to constrain NP 50

51 Charge Asymmetry in Inclusive B 0 s Decays (DØ, CDF) Measure same sign muon charge asymmetry at DØ with 1 fb -1 : With knowledge of fragmentation fractions f s and f d, the integrated oscillation probabilities χ d and χ s and known B 0 semileptonic asymmetry from B factories: A s = ± (stat+syst) Similar measurement at CDF with 1.6 fb -1 : A s = ± (stat) ± (syst) ± (inputs) These measurements can be combined with asymmetries in B s µd s X to further constraint CP violation phase. 51

52 Combined DØ Constraints on B 0 s Width Difference and CP Violation Phase Combine width difference and CP violation phase from time dependent angular analysis B 0 s J/ψφ with measurements from charge asymmetry in semileptonic decays Contours indicate 39% C.L. regions: Final combined DØ results with ~1 fb -1 : From tagged B s J/ΨΦ analysis, CDF excludes ~half available space in Φ s - Γ plane (two RHS solutions) Based on flavor SU(3) symmetry, CDF constrains strong phases to B factories measurements bottom left solution is suppressed as well. Expect tagged B 0 s J/ψφ analysis from DØ soon Expect updated analyses with 2x data from both experiments soon 52

53 - After recent observation of fastest neutral meson oscillations in B s system by CDF and DØ time to look at the slowest oscillation of D 0 mesons -D 0 mixing in SM occurs through either: D 0 Mixing short range processes long range processes (negligible in SM) M/Γ Γ/Γ K B <0.01 B 27 s 0.15 D 0 < few% < few% - Recent D 0 mixing evidence different D 0 decay time distributions in Belle BaBar D 0 ππ, KK (CP eigenstates) doubly Cabibbo suppressed (DCS) D 0 K + π - compared to D 0 Kπ compared to Cabibbo favored (CF) D 0 K - π + (Belle does not see evidence in this mode ) 53

54 Evidence for D 0 Mixing at CDF (1.5 fb -1 ) - CDF sees evidence for D 0 mixing at 3.8σ significance by comparing DCS D 0 K + π - decay time distribution to CF D 0 K - π + (confirms BaBar) - Ratio of decay time distributions: where δ is strong phase between DCS and CF amplitudes mixing parameters are 0 in absence of mixing 54

55 B h + h - signal (loose cuts) 6.5 at peak Combinatorial backg. Selection optimized to minimize statistical uncertainty on A CP (B 0 Kπ) Despite good mass resolution (@22 MeV/c 2 ), individual modes overlap in a single peak (width ~35 MeV/c 2 ) Note that the use of a single mass assignment (ππ) causes overlap even with perfect resolution Partially Reconstructed Blind Blinded region of unobserved modes: B 0 s Kπ, B 0 s ππ, L 0 b pπ/pk. Need to determine signal composition with a Likelihood fit, combining information from kinematics (mass and momenta) and particle ID (de/dx). 55

56 B h + h - signal (loose cuts) 6.5 at peak Combinatorial backg. Selection optimized to minimize statistical uncertainty on A CP (B 0 Kπ) Despite good mass resolution (@22 MeV/c 2 ), individual modes overlap in a single peak (width ~35 MeV/c 2 ) Note that the use of a single mass assignment (ππ) causes overlap even with perfect resolution Partially Reconstructed Blinded region of unobserved modes: B 0 s Kπ, B 0 s ππ, L 0 b pπ/pk. Need to determine signal composition with a Likelihood fit, combining information from kinematics (mass and momenta) and particle ID (de/dx). 56

57 B h + h - Very challenging analysis, it starts at trigger level. Then ML fit exploits information from invariant mass, momentum imbalance and de/dx. 1) M ππ invariant ππ-mass 2) α = (1-p min /p max )q min signed p-imbalance 3) p tot = p min +p max scalar sum of 3-momenta 2.1σ sep. KK/ππ de/dx carefully calibrated on pure K and π samples from 1.5M decays: D *+ D 0 π + [K - π + ] π + (sign of D *+ pion tags D 0 sign) 1.5σ K/π power separation for track p>2gev/c achieve a statistical uncertainty on separating classes of particles which is just 60% worse than perfect PID ( 75% for 2 particles) [arxiv:physics/ ] K π π K 57

58 B 0 s K- π + Tight cuts New signals Selection optimized to observe and limit setting of B 0 s K - π + First observation of three rare charmless decays: B 0 s K - π +, Λ 0 b pπ - and Λ 0 b pk - 11σ ~7000 events 8σtotal 6σ BR(B 0 s K - π + ) theoretical expectations are strongly related to a and g: QCDF, pqcd [6 10] 10-6 [Beneke&Neubert, NP B675, 333(2003)] [Yu, Li, Lu, PRD71, (2005)] SCET: (4.9±1.8) 10-6 [Williamson,Zupan,PRD74, (2006)] B 0 s Kπ yield = 230 ± 34(stat.) ± 16(syst.) [hep-ex/ ] ex/ ] 58

59 Direct A CP (B 0 s K- π + ) Observation of this decay offers a unique opportunity of checking for the SM origin of direct CP violation. Proposed in [Gronau Rosner Phys.Rev. B482, 71(2000)], later shown to hold under much weaker assumptions in [Lipkin, Phys. Lett. B621,126, (2005)]. Currently unique to CDF. From our measured BR, we can predict DCPV using: Low BR(B 0 s K + π - ) implies large asymmetry: DCPV +37% Interesting case of large DCPV predicted under SM 59

60 Direct CPV in B 0 s K- p σ [hep-ex/ ] ex/ ] = 0.84 ± 0.42(stat.) ± 0.15(syst.) (SM =1) First measurement of DCPV in the B 0 s Sign and magnitude agree with SM predictions within errors no evidence for exotic sources of CP violation (yet) It can shed light on the Belle and BaBar discrepancy. Assuming perfect SU(3) symmetry and neglecting annihilation diagrams [Buras et al., Nucl. Phys. B697, 133,2004] : A CP (B 0 p + p - ) A CP (B 0 s K- p + ). Exciting to pursue with more data, already on tape 2.5 fb

61 Gronau-Lipkin test (SM =1) From pqcd W.A. HAFG This thesis 1 (SM =0) In good agreement with our measurement A CP (B 0 s K- p + )=0.39 ± 0.15 ± Test is still marginal but sign and magnitude agree with SM predictions no evidence for exotic sources of CP violation (yet). 61

62 DCPV B 0 s K- π + : prospect Assuming SM hypothesis Gronau-Lipkin relation true today Very interesting to pursue with more data, in any case! 62

63 B 0 s K+ K - and Prospects for A CP (t ) 1 fb -1 [hep-ex/ ] Interesting comparison to predictions to evaluate the SU(3)-breaking size. Ingredients for a time-dependent A CP (t) ready: large samples (1300 ev/fb -1 ) tag dilutions calibrated, x s measured Can have σ(a CP ) ~ in runii (translate to sensitivity on γ ~ 10 deg.) (εd 2 = 5.3%) Resolution uncertainty This resolution allows tests for NP. [Baek et al, hep-ph/ ] 63

64 B 0 s D s K CP violation interesting place to probe new physics First need to understand CP processes in SM framework B meson system can help constrain hadronic uncertainties CDF provides results in B 0 s system In B 0 s D- s K+ decays, both B 0 s and antib0 s decays similar amplitude CP violation due to mixing can occur from the mixed and unmixed interference paths Need time dependent CP asymmetry measurement (later compare with B 0 DK) However! First step is observation and BR measurement. 64

65 B 0 s D s K Use displaced track trigger to gather these decays Use B 0 Dπ as control mode Primary Vertex d 0 Secondary Vertex Combined mass and particle identification likelihood fit Mass(D s π/k) de/dx of B daughter track (π/k) Detailed study of background components in MC FSR tail from B 0 s D s π (+nγ) Yield 109±19, 7.9σ observation 65

66 B 0 s mixing m m s d ~ ~ m m B B s d f 2 B f s 2 B d B B B s B d V tb V V tb * ts V * td 2 2 m s m d = ξ 2 m B s m Bd 2 V ts 2 V td m d and masses are well measured m Bs /m Bd = PDG 2006 m d = ± PDG 2006 ξ = f B s f Bd B Bs = B Bd From lattice QCD [hep-lat/051013] 66

67 Search for B 0 s Oscillations Reconstruct B s decays Measure proper decay time precisely Identify initial flavor state (B s or B s ) 1 σ = S S + B Effective tagging power: ε = efficiency of taggers D = 1 2w w = mistag prob. εd 2 figure of merit εd 2 ~ 1.5 % OST εd 2 ~ 4 % SST SεD 2 2 e σ ct 2 m 2 s /2 ct = L xy β T γ = L xy m ( B ) p T ( B ) vertexing and momentum resolution σ ct = σ L xy m(b) σ p T ct p T (B) p T (B) σ ct ~ 87 fs for hadronic decays σ ct for semileptonic decays is worse 67

68 B s J/ΨΦ Phenomenology Three angular momentum states form a basis for the final state Use alternative transversity basis in which the vector meson polarizations w.r.t. direction of motion are either: - longitudinal (0) CP even - transverse ( parallel to each other) CP even - transverse ( perpendicular to each other) CP odd Corresponding decay amplitudes: A 0, A, A At good approximation, mass eigenstates and are CP eigenstates use angular information to separate heavy and light states determine decay width difference Γ = Γ L Γ H some sensitivity to CP violation phase β s Determine B s flavor at production (flavor tagging) improve sensitivity to CP violation phase β s 68

69 Flavor Tagging The dominant b quark production mechanism produce bb pairs. We can define two zones: Opposite Side Same Side Jet Charge: the sum of charges of the b-jet tracks correlated to the b-flavour Soft Lepton (e,m) due to b lnx l charge correlated to b-flavour Same Side Kaon: for B 0 s is likely to have close in DR a K+ from fragmentation 69

70 Combined Tags 70

71 Direct CP Violation in B + J/ΨK + Decays (DØ, 1.6 fb -1 ) SM predicts small (~1%) direct CP violation in B + J/Ψ K + Due to interference between direct and annihilation amplitudes Signal yield ~28K B + J/ΨK + decays DØ reverses magnet polarities frequently good control of systematic uncertainties in charge asymmetry measurements Correct for K + /K - asymmetry Consistent with world average: but factor of two better precision best measurement 71

72 Λ 0 b Lifetime (DØ, 1.3 fb-1 ) Important test of models that describe quark interactions between heavy and light quarks within bound states HQET + Lattice QCD predicts: DØ measures Λ b lifetime two decay modes: 1.2 fb -1, ~170 signal events 1.3 fb -1, ~4400 signal events 72

73 Λ 0 b Lifetime Current Status DØ measurements are in agreement with the theoretical predictions and with the world average CDF measurement in is ~3σ high w.r.t world average Expect CDF measurement in hadronic mode soon decay mode CDF lifetime (ps), 1 fb -1 DØ lifetime (ps), 1.3 fb -1 x expected soon x 73

74 Ξ b Baryons (DØ, 1.3 fb -1 ) The third observed b baryon after Λ 0 b and CDF s recent discovery of Σ b Study b baryons great way to test QCD which predicts M(Λ b ) < M(Ξ b ) < M(Σ b ) Predicted mass: ± 8.1 MeV Discovery decay mode at DØ: x z cτ ~ 0.1 cm cτ 5 cm cτ 8 cm 74

75 Ξ b Mass Measurement (DØ, 1.3 fb-1) Clear excess in Ξ b invariant mass distribution Significance ~5.5σ Number of signal events: 15.2 ± 4.4(stat) (syst) Mass: ± 0.011(stat) ± 0.015(syst) GeV ( prediction ± 8.1 MeV) Width: ± GeV in good agreement with MC expectation GeV Production relative to Λ b J/Ψ Λ where f(b X) : fraction of times b quark hadronizes to X 75

76 Ξ b Mass Measurement (CDF, 1.9 fb-1) Ξ tracked in SVX for the first time at hadron collider reduce background improve secondary vertex precision most precise measurement at 7.8σ significance 76

77 Ξ b Current Status Ξ b also observed in hadronic decays at CDF With more data will study other properties of Ξ b 77

78 B c J/ψπ (2.2 fb -1 ) B c is not produced at B factories Precision test of lattice QCD Full reconstruction and CDF tracking give precise mass measurement New analysis Tune selection on the data: B + J/ψ K control mode Measure mass of the B c Poisson probability of background fluctuation to the observed excess is 1.1 x (Corresponds to 9σ) M(B c ) = ±3.2 ± 2.6 MeV/c M(B c ) Lattice = 6304 ± 12 MeV/c

79 B c Mass in B c J/Ψπ (CDF, 2.2 fb -1 ) B c contains both heavy quarks b, c each quark can decay Mass predictions: NR potential models MeV lattice QCD / MeV Three decay possibilities: c quark decays: b quark decays: annihilation: Best mass measurement: Signal yield 108 ±15 significance 8σ 79

80 B c Lifetime in B c J/ΨµX (DØ, 1.4 fb -1 ) Lifetime expected ~1/3 of other B mesons Main challenge in partially reconstructed mode is understanding multiple backgrounds: real J/Ψ + fake muon fake J/Ψ + real muon real J/Ψ + real muon from bb events where K µνν prompt J/Ψ + µ Mass lifetime simultaneous fit used to disentangle small signal fraction among large fraction of backgrounds - Most precise B c lifetime measurement: 80

81 Implications 81 81

82 R. Dermisek et al., JHEP 0304 (2003) 037 Gli spazi per New Physics si riducono SO(10) GUT R. Dermisek et al., hep-ph/ (2005) tan(b)~50 constrained by unification of Yukawa couplings Pink regions are excluded by either theory or other experiments Green region is the WMAP preferred region Blue dashed line is the Br(Bs mm) contour. Light blue region excluded by old Bs mm analysis