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Intae Yu

B Physics Analysis and Plan at SKKU. Intae Yu. Sungkyunkwan University, Suwon, Korea Tevatron B Physics workshop @ KISTI, August 24 th , 2009. SKKU CDF group: Brief Review. Current Group: 1 faculty, 1+? graduate students Past Research Activities TOF PMT Test and Calibration

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Intae Yu

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  1. B Physics Analysis and Plan at SKKU Intae Yu Sungkyunkwan University, Suwon, Korea Tevatron B Physics workshop @ KISTI, August 24th, 2009

  2. SKKU CDF group: Brief Review • Current Group: 1 faculty, 1+? graduate students • Past Research Activities • TOF PMT Test and Calibration • CDF Note 5386 • COT Tracking Efficiency • CDF Note 6394, 6594 • Bs Lifetime CDF Note 6195, 6395 • Bc Meson Lifetime and Cross Section CDF Note 7518, 7926, 7985: PRL 97, 012002 (2006) • Cabibbo Suppressed Decays of B+ Meson CDF Note 6967, 7763, 8236, PRD 79, 112003 (2009)

  3. 쳑Current Research Activity • Exclusive Decays of B Mesons to X(3872) • Provides important clues to structure of X(3872) • Analyzed 1.4 fb-1 of data • Present preliminary results at a CDF internal meeting • Decay modes: • B+→X(3872)K+ : Observed. Consistent with Belle and Babar Results • B0→X(3872)K0 : Analysis is in progress

  4. Physics Motivation • X(3872) was first discovered by Belle in charged B meson decay and later confirmed by Babar in the same mode (B+ → X(3872)K+, X(3872) →J/ψπ+π-). • Also observed at CDF and D0 in X(3872) →J/ψπ+π- decay • We reconstruct B→X(3872) K exclusive decays and measure the branching fractions and masses of X(3872) in each mode • The result of this analysis provides an important information to check various interpretations for X(3872) - molecule model, tetraquark model, charmonium,…. • Belle and Babar measured the mass difference and relative branching ratio of B0→X(3872)K0 to B+→X(3872)K+ in 2008 and their results show some inconsistency 0.18±0.89±0.26 MeV/c2 0.82±0.22±0.05 (Belle) 2.7±1.6±0.4 MeV/c2 0.41±0.24±0.05 (Babar) < 3.2 MeV/c2 (90%CL)(CDF)

  5. Decay Topology and Reference Mode [Decay topology of B+ mode] [Decay topology of B0 mode] • Choose B→ψ(2S)K, ψ(2S)→J/ψπ+π- decay as the reference mode • Same final states (J/ψπ+π-K) • Similar kinematics (ΔM(ψ(2S), X) ~ 185 MeV/c2) • Enough number of events in both B+→ψ(2S)K+ and B0→ψ(2S)K0 decays

  6. Reconstruction of • Clear peak of B+ meson observed • Unbinned fit with Gaussian+2nd order polynomial (rhs) • Yields 49.7 ± 12.3 signals • Statistical significance of

  7. Relative Branching ratio • Relative branching ratio of B to XK to B to ψ(2S)K can be measured : • : # of candidates in X(3872) mode • : # of candidates in ψ(2S) mode • : Overall signal efficiency in X(3872) mode • : Overall signal efficiency in ψ(2S) mode • Use same cuts to ψ(2s) mode (to minimize systematic) • Except the dipion mass cut Mππ> 0.5 GeV/c2 for X(3872), 0.31 < Mππ<0.61 GeV/c2 for ψ(2S)

  8. Observed Number of Signals Fit with single gaussian and 2nd order polynomial

  9. Relative signal efficiency & Relative Branching Fraction • Generated 4,928,804 events in both of modes B PT> 5GeV/c & |η| <1.3 • After applying final cuts, • 15,634 candidates remain in ψ(2S) mode • 19,825 candidates remain in X(3872) mode • The relative efficiency was measured to be : • Combining the above, we get the relative branching fraction as follows:

  10. Systematic • Most of the systematic errors cancel out • Counting number of signals – Fitting • Possible bias/errors in fitter • Check pull distribution • Fitting range • Observe effect of variation of fitting range • Efficiency measurement • MC generator : assumption of dipion mass spectrum • Observe changes of result with measured dipion mass histogram

  11. Systematics : Summary • Preliminary Result:

  12. Selection for B0 mode • Ks has long decay length : • No SVX hit requirements for pion tracks from Ks • Refit tracks setting setInnerRadius() for material integration • Follow selections in K+ modes • Similar kinematics • Inherit cut sets from K+ modes • Ks selection • Lxy > 0.1 • 3σ mass range

  13. MC generation & Efficiency calculation • Same algorithm used in K+ mode (phase space decay with dipion mass spectrum) • S-wave parameterization forψ(2S) decay • Non-relativistic BW for X(3872) decay • # of MC events after final cuts • ψ(2S) : 4298 passed in 2,976,709 events • X (3872): 5306 passed in 2,999,816 events • Relative efficiency (stat. only)

  14. B0→Ψ(2S)K0s • Mass fit in B0→Ψ(2S)K0s mode • Gaussian + 1st order polynomial • 73.2 signals observed gFrac=0.389±0.042gMean=5.278±0.001sigma=0.096±0.001slope=-6.071±1.908 nSig=73.18±7.908

  15. Efficiency Check • In B0 mode, we plan to measure R R = Br(B0→X(3872)K0)/Br(B+→X(3872)K+) R < 0.1 in molecule models R ~ 1 in the tetraquark model • To check the MC relative efficiency between B0 and B+ in X mode, we measure the relative branching ratio of two reference modes using MC efficiencies and compared it with PDG value. PDG average is : 0.331 ± 0.037 Assume σ(B0) = σ(B+) • Preliminary analysis of B0 → X(3872)K0s is in progress

  16. Summary • Observation of • Yield : 49.7 ± 12.3 • Statistical significance : Ratio of Branching Fractions in B+ modes • Study of B0→X(3872)K0s • Reference mode B0→ψ(2S)K0s is reconstructed • Analysis of B0→X(3872)K0s mode is in progress

  17. Prospects • Exclusive Decays of B Mesons to X(3872) • Process more data (currently 5.6 fb-1) • Systematic uncertainties to be investigated • B+→X(3872)K+ , B0→X(3872)K0 : branching ratio and mass • B0→X(3872) K+π- mode : in preparation (reported by Belle) • Get blessed asap and go to publication

  18. Research Interests • Search for Z(4430)+ • Discovered at Belle in the decay Z(4430)+ → ψ(2S)π+ • Not observed at Babar (need independent confirmation) • Search for Exotic States in the Upsilon system • Unusually large partial width Υ(5S)→Υ(1S) π+π-,Υ(5S)→Υ(2S) π+π- (Belle) • Possible exotic state Z’ → Υ(1S) π+, Υ(2S) π+corresponding to Z(4430) • (M. Karliner, H.J. Lipkin, arXiv:0802.0649 ) • New Bs Decays • Bs → J/ψKs • Bs → X(3872)φ→ J/ψπ+π-φ • Welcome suggestions and discussions 18

  19. CDF France Korea FKPPL Workshop LPNHE Paris, June 29-July 1 http://lpnhe-cdf.in2p3.fr/cdf_Fr_Korea/

  20. FKPPL Workshop • FKPPL (France-Korea Particle Physics Laboratory) • KISTI-LPNHE Joint Project • FKPPL-CDF Workshop (June 29 ~ July 1 @ Paris) • probes the possibility of Korea-France Collaboration • 1st Day : B Physics Session • CP Violation in Bs system • New Bs decays 20

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