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B 0 (s)  h + h ’ - decays at CDF

B 0 (s)  h + h ’ - decays at CDF. HEP2005 International Europhysics Conference on High Energy Physics July 21 st – 27 th , 2005 – Lisboa, Portugal Diego Tonelli tonel@fnal.gov Istituto Nazionale di Fisica Nucleare, Pisa for the CDF Collaboration. TREE. PENGUIN. Motivation.

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B 0 (s)  h + h ’ - decays at CDF

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  1. B0(s)  h+h’- decays at CDF HEP2005 International Europhysics Conference on High Energy Physics July 21st – 27th, 2005 – Lisboa, Portugal Diego Tonelli tonel@fnal.gov Istituto Nazionale di Fisica Nucleare, Pisa for the CDF Collaboration Diego Tonelli, CDF - Pisa

  2. TREE PENGUIN Motivation Joint study of B0and B0s2-body decays into charged kaons and pions (KK,  andK): a privileged insight into flavor physics and a useful tool in searching for New Physics. CDF has simultaneous access to both B0/B0s h+h'-decays:  flavorphysics program complementary to Y(4S). R. Fleischer PLB459:306-320, 1999 - constrain hadronic unknowns with SU(3) symmetry. Use approximated s dquark symmetry (i.e. measure jointly B0and B0s) to extract phase . WEAK amplitude theoretically clean HADRONIC/ EW theoretically uncertain Diego Tonelli, CDF - Pisa

  3. Motivation (cont’d) Fleischer’s method needs: time-dependent asymmetries in b-flavor tagged samples, size of SU(3) breaking, sin(2) and msCDF ultimate long term goal. Currently accessible BR can constrain theory too: compare CDF measurements with allowed regions in spaces of B0 +- and B0s K+K-observables (Y(4S) and theory): a probe for both  and NP Fleischer and Matias PRD66: 054009,2002 - London and Matias PRD70:031502, 2004. …many other interesting measurement, e.g. s/s in B0s K+K-see talk by M. Donega’ - Friday 17.08 Room 5. Diego Tonelli, CDF - Pisa

  4. PLANE  TO THE BEAM B pT(h2) pT(B) pT(h1) Secondary vertex IP(h1) IP(B) Primary vertex Experimental challenge #1: write signal events to tape • S/N at production ~10-9; • high track multiplicity per event; • generic final states (2 tracks, K and/or ) in huge QCD BCKG. • Crucial role of trigger: • Reconstruct silicon tracks online. Trigger on displaced secondary vertices with ~30 m impact parameter (IP) resolution. • large (B)  large B decay length and IP of tracks; • pp  bb + XB from primary vertex, small IP of B. Diego Tonelli, CDF - Pisa

  5. Analysis overview SIGNAL RECONSTRUCTION unbiased optimization of the selection requirements (use MC and data) dE/dx CALIBRATIONS Accurate calibrations of dE/dx with D*+ decays FIT OF COMPOSITION Unbinned ML fit: kinematics and dE/dx to distinguish each B0(s)  h+h'- mode SIGNAL SIMULATIONRealistic MC sample BR RATIOS and ASYMMETRIES Correct raw fit results for trigger / selection efficiencies (use MC and data) CONTROL SAMPLESB0s and B0 exclusive decays in J/X and D Diego Tonelli, CDF - Pisa

  6.  -  space B Experimental challenge #2: signal extraction Unbiased optimization of selection cuts: maximize S/(S + B) with signal from MC and background from data sidebands. isolation: fraction of pT carried by the B candidate after fragmentation. Rejects 15% of signal and 400% of background. Diego Tonelli, CDF - Pisa

  7. Experimental challenge #3: peak composition • Excellent CDF mass resolution: • 5 silicon layers + drift chamber measure pT in 1.4 T solenoidal field with 132 cm lever arm •  resolution ~ (0.7  0.1 pT)% • Still, the four (expected) major modes overlap into an unresolved mass peak. • Extract composition statistically with an unbinned 5-dimensional ML fit. Combine information from: • kinematics (mass and p); • particle ID (dE/dx). B0 modes B0s modes simulated signals Diego Tonelli, CDF - Pisa

  8. MC MC MC B0 +- + c.c. B0 K+- MC MC MC B0 K-+ B0s K+- B0s K-+ B0s K+K- + c.c. Peak composition handle 1: kinematics -mass vs signed momentum imbalance: (1- pmin/pmax)qmin discriminates among modes (and flavors in K modes). Diego Tonelli, CDF - Pisa

  9. Peak composition handle 2: specific ionization in the drift chamber • Tracks have hits in drift chamber: • 96 layers, |η| ≤ 1.0; • 44 cm < r < 132 cm, 30k channels; • σ(hit) ~ 180 μm; • dE/dx encoded in hit pulse-width. TIME OF FLIGHT Accurate, time dependent dE/dx calibration using ~95% pure K / samples from ~70k decays: D*+D0 + [K-+] + + c.c. Strong D*+ decay tags the D0 flavor. Diego Tonelli, CDF - Pisa

  10. dE/dx vs  dE/dx vs hits corrected corrected raw raw Peak composition handle 2: dE/dx (cont’d) Angle, gas pressure, time and hit-multiplicity dependences corrected. 1.4K/ separation at p > 2 GeV/c ( 60% of “perfect” separation) Residual gain fluctuations cause correlated dE/dx shifts: measured and included in the fit of composition. Diego Tonelli, CDF - Pisa

  11. Raw fit results What we measure: ~900 evts/180pb-1 in initial CDF data, taken with still non optimized detector/trigger. Now much better: ~2700 / 360 pb-1 Diego Tonelli, CDF - Pisa

  12. Efficiency/acceptance corrections Correct for relative acceptance, trigger and selection effic.: 5 -10% Kinematics and nuclear interaction efficiencies (Monte Carlo) Trigger-bias: correct for dE/dx-dependent trigger efficiency (D+ data) Isolation efficiency, measured from exclusive decays (B0 and B0s data) Diego Tonelli, CDF - Pisa

  13. Dominant systematic uncertainties (stat. ~ 7.8%) syst. ~ 1.2% (stat. ~ 29%) syst. ~ 13% (stat. ~ 17%) syst. ~ 15% (stat. ~ 24%) syst. ~ 14% • dE/dx track-to-track correlations (partially reduces with statistics); • B-meson masses input to the fit (reduces with statistics); • Relative isolation efficiency between B0s and B0(reduces with statistics); • Effect of final state radiation; • Trigger bias on efficiency; • Charge-dependence of dE/dx; • Background shape; • Charge asymmetries in background; • Others. Diego Tonelli, CDF - Pisa

  14. Final results: B0s sector B0s K+K- decay established. BR ratio may favor large SU(3) breaking as predicted from sum rules (Khodjamirian et al. PRD68:114007, 2003). Allows first comparisons with Y(4S) and theory expectations, test of NP. No evidence for B0s  K-+, set a limit a factor ~40 better than PDG04. Great improvement on annihilation mode B0s   -+. A factor >100 below PDG04 (time-evolutions of B0s  -+ and B0s  K-K+ assumed the same). Diego Tonelli, CDF - Pisa

  15. Final results: B0 sector ACP compatible with B-factories, systematic uncertainty comparable as well, Babar statistic uncertainty just ~30% better with same sample size. With currently available data (3x statistics), we expect < 4.5% statistical uncertainty to be compared with current world best: 2.2% (Belle). Limit on pure annihilation/exchange mode B0 K+K-. A factor ~2 above B-factories, expect much better performance on current sample. Consistent with B-factories. Valuable cross-check for other measurements. Diego Tonelli, CDF - Pisa

  16. Concluding remarks • CDF has unique joint access to B0/ B0s h+h'-modes: rich physics program complementary to B-factories. Results shown ready for PRL submission in first B0(s)  h+h'-paper from an hadronic collider: • B0sK+K- decay established and BR measured (first B0s  PP observed); • x100 improvement with respect to PDG04 on the upper limit on BR(B0s  +-) and x40 improvement on the limit on BR(B0s  K-+); • measurement of ACP (B0 K+-) with small systematics. • Just the beginning: now 900 pb-1 on tape, of which 360 ready for analysis with ~2x increase in yield/pb-1 (optimized efficiencies), improved mass resolution (better tracking alignment and reconstruction). By end of 2005 we expect: • Observe B0s  K-+and reduce to ~10% statistical error on BR(B0s  K+K- ); • ACP (B0 K+-) much closer to Y(4S) with ~4% statistical uncertainty; • World best limits on BR(B0s  +-) and on BR(B0 K+K-). Diego Tonelli, CDF - Pisa

  17. ADDITIONAL MATERIAL Diego Tonelli, CDF - Pisa

  18. The Tevatron pp collider Superconducting proton-synchrotron: 36 p 36 p bunches collision every 396 ns at√s = 1.96 TeV Luminosity…………………………….: record peak is 1.3  1032 cm-2 s-1 ~ 10 pb-1 / week recorded on tape # interactions / bunch-crossing……..: < N >poisson = 6 (at 2 1032 cm-2s-1) Luminous region size………………..: 30 cm (beam axis)  30 m (transverse) need long Si-vertexsmall wrt c(B) ~ 450 m 2005, regularly exceeds 1032 cm-2s-1 Diego Tonelli, CDF - Pisa

  19. Delivered Luminosity ~ 900 pb-1 on tape 1 fb-1 milestone! data for physics Feb 2002 April 2001 Jul 2002 first data for analyses detector commiss. Stable data taking efficiency: ~85% The results shown here from an analysis that uses ~180 pb-1 Diego Tonelli, CDF - Pisa

  20. CDF Heavy Flavor physics at the Tevatron The Good bb production x-section O(105) larger than e+e- at (4S) /Z0. Incoherent strong production of all b-hadrons: B, B0, Bs, Bc, b, b . The Bad Total inelastic x-section ~ 103  (bb). BRs’ for interesting processes O(10-6). …and The Ugly Messy environments with large combinatorics. Need highly selective trigger Diego Tonelli, CDF - Pisa

  21. 1.4 T magnetic field Lever arm 132 cm 7-8 silicon layers 1.6< r <28 cm |z|<45 cm |η| ≤ 2.0, cosθ = 0.964 σ(hit) ~ 14 μm 132 ns front end COT tracks @L1 SVX tracks @L2 30000 /300 / 70 Hz ~no dead time Some resolutions: pT ~ (0.7  0.1 pT)% J/Ψ mass ~15 MeV EM E ~ 16%/√E Had E ~ 100%/√E d0 ~ 6+22/pTμm Primary vtx ~10 μm Secondary vtx r-Φ ~ 14 μm r-z ~ 50 μm Time-of-flight 100 ps @150cm p, K, π id 96 layer drift chamber |η| ≤ 1.0 44 < r < 132 cm, 30k channels σ(hit) ~ 170 μm dE/dx for p, K, π id Tile / fiber endcap calorimeter 1.1 < |η| <3.5 • coverage to ||≤1.5 80% in  CDF Detector Upgrades Diego Tonelli, CDF - Pisa

  22. Triggering bs’ (and cs’) conventional new approach Di-lepton B  charmonium Rare B  Two muons with: pT> 1.5 GeV ||< 1 pT> 2.5-4.5 GeV ||<2 electron or  and displaced track Semileptonic decays Electron () with: pT> 4 (1.5) GeV ||< 1 and one trackwith: pT > 2.0 GeVIP > 120 m Two displaced tracks n-body hadronic B Two tracks with: pT > 2.0 GeV pT > 5.5 GeV IP > 120 (100) m Displaced track trigger at Level 2: a revolution in hadronic environment ! Makes it accessible rare hadronic decays with high S/B. Diego Tonelli, CDF - Pisa

  23. Systematics - detailed Diego Tonelli, CDF - Pisa

  24. Raw physics results Diego Tonelli, CDF - Pisa

  25. Raw physics results Diego Tonelli, CDF - Pisa

  26. Corrected results Diego Tonelli, CDF - Pisa

  27. Correlation matrix Legenda Diego Tonelli, CDF - Pisa

  28. p.d.f. projection: momentum imbalance Diego Tonelli, CDF - Pisa

  29. p.d.f. projection: |p(1)| + |p(2)| Diego Tonelli, CDF - Pisa

  30. p.d.f. projection: dE/dx Diego Tonelli, CDF - Pisa

  31. p.d.f. projection: dE/dx Diego Tonelli, CDF - Pisa

  32. Momentum p.d.f. Binned ML fit Monte Carlo p p   signal background Diego Tonelli, CDF - Pisa

  33. dE/dx model Diego Tonelli, CDF - Pisa

  34. Silicon Vertex Trigger Diego Tonelli, CDF - Pisa

  35. SVT Silicon Vertex Trigger (cont’d) (35  33) mm SVT  beam  s = 48mm Diego Tonelli, CDF - Pisa

  36. B0sK+K- lifetime B0lifetime from PDG04. B0sK+K- lifetime depends on: - s/s : width difference between “long” and “short” eigenstates -the relative composition in short and long-lived components Assume Standard Model s = d and s /s = -0.12  0.06 B0sK+K-is expected almost 100% “short-eigenstate”Fleischer and Matias:PRD66-054009,2002) Therefore the lifetime of B0sK+K- is determined as: Diego Tonelli, CDF - Pisa

  37. Physics Motivations (backup) The combination of Bdand Bsdecays provides a promising way to extract CP-related physical parameters avoiding the “penguin pollution”.(R. Fleischer PLB459 (1999) 306) Assume U-spin symmetry (d  s), the ACP are function of the CKM angles  and  and of the amplitude ratio P/T (~ dei)  4 equation with 4 unknowns (, , d, ). A combined fit of the 4 CP asymmetries measures,  and P/T ratio. Above strategy need time-dependent analysis with tagged samples: long term goal Diego Tonelli, CDF - Pisa

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