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G.P. Di Giovanni LPNHE - Univ. “Pierre et Marie Curie” - IN2P3/CNRS

B s Mixing, DG s & CP Violation. G.P. Di Giovanni LPNHE - Univ. “Pierre et Marie Curie” - IN2P3/CNRS XLIIId Rencontres de Moriond EWK, 2008. Synopsis. Theoretical Introduction Neutral B s Meson System: B s Oscillation Frequency

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G.P. Di Giovanni LPNHE - Univ. “Pierre et Marie Curie” - IN2P3/CNRS

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  1. Bs Mixing, DGs & CP Violation G.P. Di Giovanni LPNHE - Univ. “Pierre et Marie Curie” - IN2P3/CNRS XLIIId Rencontres de Moriond EWK, 2008

  2. Synopsis • Theoretical Introduction • Neutral Bs Meson System: • Bs Oscillation Frequency • Lifetime Difference and CP Violation Phase in Bs  J/Y F • Charge Asymmetry in Bs Semileptonic Decays • Charge Asymmetry in B+  J/Y K+ • Summary G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  3. Pure Bs and Bs at production: Neutral Bs System Flavor eigenstates: ( ) Mass eigeinstates are (|p|2+|q|2=1):  Different Masses: defines the Mixing Oscillation Frequency  Different Lifetimes: CPV: Small Phase expected in SM 1 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  4. Bs Mixing Oscillation CDF: World First Observation (5s) • Integrated Luminosity: 1 fb-1 D: Evidence (3s) • Integrated Luminosity: 2.4 fb-1 • First D measurement using • a hadronic mode • Consistent with CDF result 2 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  5. Im MSM MNP Re MSM+MNP CP Violation in Bs System • Bs mixing oscillation observed by CDF: • is well measured • Precisely determines in good agreement with the Standard Model • Phase of the mixing amplitude is instead • poorly determined • Both are needed to constrain New Physics: Large value of CP Violation phase FM is a clear sign of New Physics! 3 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  6. bs CP in Bs  J/  Decays • CP Violation arises from the interference between mixing and decay: • Unitarity Triangle in Bs System: • CP violation phase bs in SM is predicted to be very small: • Same New Physics affects the CPV phases as • If NP phase dominates  4 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  7. Phenomenology of Bs  J/  • Nice experimental signature for B physics at hadron machines • Decays into an admixture of CP even (~75%) • and CP odd (~25%) •  Mass and CP states are very close • C-even Different ParitySeparate CP contributions • decays leads to three different angular momentum final states: • L=0 (S-wave), L=2 (D-wave)  P-even • L=1 (P-wave)  P-odd • Angular Analysis to separate the different • parity contributions • Transversity Basis • Sensitivity to and CP-Violation phase • (also in untagged sample due to CP-even/CP-odd interference) 5 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  8. Strong phases: Signal PDF for Bs J/  General decay rate formula: • Bs decays into mixture of CP eigeinstates: • interference terms in general decay rate • formula • In the Transversity basis the vector meson • polarization w.r.t the direction of motion is: • Longitudinal  A0 [CP even] • Transverse and parallel to each other  A|| [CP even] • Transverse and perpendicular to each other  A [CP odd] • Terms with Dms dependence • flip sign for initial Bs flavor • Untagged analysis are insensitive • to DGs and bs signs 4-fold ambiguity 6 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  9. Bs Lifetime and Decay Width • Sizeable DGs CP-even and CP-odd contributions of the signal can be distinguished • Results assuming noCP violation  bs=0 D: ~1040 signal events (1.1 fb-1) CDF: ~2500 signal events (1.7 fb-1) PRL 98, 121801 (2007) World Best DGs Measurements (arXiv: 0712.2348) Lifetime: Decay Width: • B0  J/ K*0: CDF validates treatment of detector acceptance! •  Results compatible and competitive with B Factories (back-up slides) 7 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  10. CP in Untagged Bs J/  • Allowing CP violation phase bs to float in the fitter • Symmetry in the likelihood 4-fold ambiguity • D quotes a point estimate: •  •  • CDFobserves irregular likelihood and biases in fit •  Feldman-Cousins confidence region: SM probability pvalue=22% (1.2s) arXiv:0712.2348 PRL 98, 121801 (2007) Standard Model expectations: DGs=0.096  0.039 ps-1 2bs = 0.04 0.01 rad (arXiv:hep-ph/0612167) --- 1s contour (39% CL) 8 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  11. 2bs-DGs likelihood profile Untagged Tagged 2DlnL = 2.31 (68% CL) 2DlnL = 5.99 (95% CL) Flavor Tagging Effect • Tagging improves sensitivity to CP violation phase bs • Exact symmetry present in signal probability distribution • Two minima in the likelihood • Check bs-DGs likelihood profile with Toy MC to • understand tagging effect • Likelihood: with tagging, gain sensitivity to • both |cos(2bs)| and sin(2bs), rather than • only |cos(2bs)| and |sin(2bs)| (note absolute • value) • bs -bs is no longer a likelihood symmetry: • 4-fold ambiguity reduced to 2-fold • allowed region for bs is reduced to half 9 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  12. CP in Tagged Bs J/  • First tagged analysis of Bs → J/ΨΦ decay • CDF: ~2000 Bs events with 1.35 fb-1 • Tagging power  OST: e=(96  1)% <D> = (11  2)% •  SST: e=(50  1)% <D> = (27  4)% • Irregular likelihood does not allow quoting point estimate: • Feldman-Cousins likelihood ratio ordering arXiv: 0712.2397 strong phases can separate the two minima Standard Model expectations: DGs=0.096  0.039 ps-1 2bs = 0.04 0.01 rad (arXiv:hep-ph/0612167) Standard Model pvalue = 15% (1.5s) 10 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  13. 2bs p 0 2bs p 0 2bs p 0 CP in Tagged Bs J/  1-dim Feldman-Cousins procedure on CP violation phase bs • 1. Without External Constraints: • 2bs in [0.32, 2.82] at the 68% C.L. • 2. DGs is theoretically constrained: • Input DGs = 2|G12|cosFs 2|G12|cos(2bs):(G12=0.0480.018): • 2bs in [0.24, 1.36] U [1.78, 2.90] at 68% C.L. • 3. Strong phases from Bd  J/Y K*0 [PRD 71, 032005 (2005)], • Bs lifetime from Bd[PDG] and DGs 2|G12|cos(2bs): • 2bs in [0.40, 1.20] at 68% C.L. 11 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  14. CP in Tagged Bs J/  • Tagged analysis of Bs → J/ΨΦ decay from D • D: ~2000 Bs events with 2.8 fb-1 • Combined Tagging Power  eD2 = (4.68  0.54)% • Quoting point estimate: arXiv: 0802.2255 FIT inputs: Dms fixed to 17.77 ps-1 Gaussian constraint on Strong phases: d-d||=-0.46  (p/5) d=+2.92  (p/5)  CDF  B Factories Standard Model expectations: 2bs = 0.04 0.01 rad 90% C.L. contours: (arXiv:hep-ph/0612167) CDF 68% CL: Constraining lifetime, strong phases and G12 Standard Model pvalue = 6.6% 12 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  15. Charge Asymmetry • CP Violation in mixing • if  • Combine these results with Bs  J/ measurements to constrain phase bs • CDF: 1.6 fb-1 of data collected (di-muon charge asymmetry): (http://www-cdf.fnal.gov/physics/new/bottom/070816.blessed-acp-bsemil/) • D: 1.0 fb-1 of data collected (di-muon charge asymmetry): PRD 74, 092001 (2006) • D: 1.3 fb-1 of data collected (Bs semileptonic decays): PRL 98, 151801 (2007) 13 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  16. Constraints on bs New Physics in Bs mixing: UTfit Group (http://www.utfit.org/) Dms=CBs*DmsSM: Lattice-QCD dominated uncertainty bs=bsSM - FBs: Experimentally dominated uncertainty D Result: CDF input: Tagged Bs J/Y F analysis reduces ambiguities CDF 68% CL: Constraining lifetime, strong phases and G12 UTfit inputs: Dms measurement (CDF) Lifetime ts (CDF and D) DGs (CDF on 200 pb-1) DGs and Fs (D on 1.1 fb-1) Semileptonic ASL (D) B Factories input: Assuming SU(3) symmetry negative DGs solution excluded UTfit combination 14 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  17. Direct CP in B+ J/Y K+ • Charge asymmetry • Direct CP violation due to interference between direct and annihilation amplitudes: In SM ACP(B  J/ K) predicted to be of the level of 1% • D: ~40K signal events on 2.8 fb-1 • Consistent with the PDG-2007 world average • ACP(B  J/ K)=0.015 0.017 • Factor 2 better precision • Most stringent bound on NP model predicting large ACP(B+  J/Y K+) • ACP(B+J/Y p+)= -0.09  0.08 (stat)  0.03 (syst) arXiv:0802.3299 15 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  18. Conclusions • Tevatron has a very active program in B Physics, with relevance to the Bs sector • Complementary and competitive with B Factories • CDF and D search for CP violation effects: • Direct CP violation (B+ J/Y K+) • CP Violation in Mixing: precise measurement • CP Violation in the interference between mixing and decay: FIRST sin(2bs) measurement • Interesting sin(2bs) fluctuation at Tevatron experiments: • Exclude large negative values • Both experiments, CDF and D • In the same direction of ASL • Almost 3.5 fb-1 of data delivered • New results with larger dataset coming soon! 16 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  19. Backup Slides

  20. CKM Matrix • In Standard Model Mixing and CP Violation effects are described • within the CKM mechanism: • Unitarity condition for CKM matrix: V†V=1 • Expanded in terms of l=sin(qc)~0.23 • Phase h responsible for CP Violation Large CPV Suppressed CPV • Unitarity Triangle: • Standard Model does not • predict values • Experimental Input is crucial 17 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  21. The Tevatron • collisions at 1.96 TeV • Excellent Performance • Peak Initial Luminosity: 3 x 1032 cm-2 s-1 • Challenge for Detectors, Triggers and • Reconstructions • B physics benefits from more • data • The analyses presented in this • talk span from 1.0 to 2.8 fb-1 • Currently on tape ~3 fb-1 18 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  22. Tevatron Detectors CDF II Detector • Tracker: - Silicon Vertex Detector • - Drift Chambers • Excellent Momentum Resolution • Particle ID: TOF and dE/dx • Triggered Muon Coverage D Detector • New L00 installed in 2006! • Solenoid: 2T, weekly reversed polarity • Excellent Calorimetry and electron ID • Triggered Muon Coverage 19 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  23. Transversity Analysis: B0 J/Y K*0 • Measurements of amplitudes and strong phases using transversity basis • Validation sample for the angular analysis on Bs J/Y F • CDF: ~7800 signal events on 1.35 fb-1 • Correct treatment of detector acceptance • Results comparable and competitive with BaBar [Phys. Rev. D 76, 031102,(2007)] 20 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  24. e.g., if ΔΓ=0, δ┴ is undetermined: Untagged Analysis: Bias • Biases • Non-Gaussian estimates in • pseudo-experiments • Strong dependence on true values • for biases on some fit parameters Fits on simulated samples generated with SM inputs for DGs and bs • Dependence on one parameter in the likelihood vanishes for some values of other parameters: Likelihood looses degrees of freedom 21 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  25. Constraints on Tagged Bs J/  • SU(3) flavor symmetry suggests that Bs and B0 have similar lifetimes • and strong phases • Likelihood profiles with external constraints from B factories • Underestimated confidence regions when using 2DlnL = 2.31 (5.99) • to approximate 68% (95%) C.L. regions constrain strong phasesconstrain lifetime and strong phases  External constraints on strong phases remove residual 2-fold ambiguity 22 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  26. Charge Asymmetry (I) • Semileptonic decay Bs m+ Ds-n X, Ds-  f p-, f  K+K: • if  • Sensitivity to phase : NP does not take much to modify the • SM prediction • If NP dominates • Can combine this result with the measurement • from Bs  J/ to constrain the phasebs PRL 98, 151801 (2007) • D: ~27k signal events (1.3 fb-1) PRL 98, 151801 (2007) • Detector asymmetries highly reduced by D regular change of magnet polarity • Additional statistics and new decay modes will improve the result 23 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  27. Related to : additional constraint on bs Charge Asymmetry (II) • Inclusive dimuon charge asymmetry • D: 1.0 fb-1 of data collected by Tevatron fq is the production rate of Bq mesons in the hadronization of the b quark • Using world averages for fq, the semileptonic asymmetry for Bd from • B factories and the measured parameters Dmq and DGq: PRD 74, 092001 (2006) • CDF: 1.6 fb-1 of data collected by Tevatron (http://www-cdf.fnal.gov/physics/new/bottom/070816.blessed-acp-bsemil/) 24 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

  28. Magnet Polarity Inversion • D performs a regular change of magnet polarity: • Reduce artificial asymmetry in the detector • Systematics effects in charge asymmentry analyses cancel out • Methodology described in Phys. Rev. D 74, 092001 (2006): 1. Divide the sample in 8 subsamples corresponding to all possible combination of toroid polarity b=1, pseudorapidity sign of the system considered g=1 and charge of the muon particle q =1 2. Solve the system of equations: • ebis the fraction of integrated luminosity with toroid polarity b (e++e-=1) • Ais the integrated charge asymmetry to be measured • Afb is the forward-backward asymmetry • Adetis the detector asymmetry for particles emitted in fwd and bwd directions • Aro is the range out asymmetry: muons acceptance changes if muons • bends towards or bend away the beam line • Aqbis the detector asymmetry which accounts for muons reconstruction • efficiency when toroid polarity is reversed • Abgis the detector related asymmetry fwd-bwd remaining after toroid polarity flip • Nis the total number of events 25 G.P. Di Giovanni, Univ. “Pierre et Marie Curie” - IN2P3/CNRS

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