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Absolute Branching Fractions Measurements for Exclusive D s Semileptonic Decays

Absolute Branching Fractions Measurements for Exclusive D s Semileptonic Decays. Koloina Randrianarivony Marina Artuso ( Syracuse University ). Outline. Analysis Method and Results Signal MC → efficiencies Generic MC (x20 Data) → validation of the method, background estimate

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Absolute Branching Fractions Measurements for Exclusive D s Semileptonic Decays

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  1. Absolute Branching Fractions Measurements for Exclusive Ds Semileptonic Decays Koloina Randrianarivony Marina Artuso (SyracuseUniversity)

  2. Outline • Analysis Method and Results • Signal MC → efficiencies • Generic MC (x20 Data) → validation of the method, background estimate • Data → B • Systematic Error estimate Ds Exclusive Semileptonic

  3. Analysis Techniques e+ e- (1--) Ds-(Ds-*) Ds+* (Ds+) + ... TAGGED SIDE: K+K-p- KsK- p- (+-)p- K+K- p-p0 +-- K*K*(KsK-+-) - ph' (rg) SIGNAL SIDE F(K+K-) e+n, K*0(K+-) e+,K0(+-)e+n f0(p+p-) e+n, h(gg) e+n and '(+-) e+ + CC Event Ds Exclusive Semileptonic

  4. Shower selection • Not matched to charged tracks • e9oe25OK() • From goodBarrel with a reconstruded • energy greater than 30MeV, if in • goodEndcap it should be greater than 50MeV • (before only good barrel used) • Track Quality Cuts: • Hit fraction > 0.5 • Good fit • |d0|<0.5cm and |Z0|<5.0cm • |cosθ| < 0.93 • |p| >0.04 GeV • Particle ID • Both dE/dX & RICH PID if |p| > 0.7GeV • dE/dX PID if 0.2 < |p| < 0.7 GeV • 4σ dE/DX consistency cut if |p| < 0.2 GeV, from Radia’s analysis (CBX 05-24). Selection criteria Signal side gg Use NavEtaGG and get the smallest pull mass. No p0 veto cut. No splitoff used. Make sure that the daughters of the h are not the same as the photon used with the tag h(hpp) Use the best h candidate and add 3 charged tracks. 10 MeV from nominal h mass K0 (K0s) PID for the 2 Pions Pull mass within 3.0 s Flight significance > 2 f0(pp) PID for both Pions 0.880< | f0Mass-PDG|< 1.080 GeV K*0(Kp) PID for both Pion and Kaon | K*0Mass-PDG|< 1.5 Г=0.075 GeV F(KK) PID for the 2 Kaons |f Mass – MPDG| < 20 MeV Ks on the tags From TCleanV0c, c2 >0 and prob() > 0 Use Cleo2RareBK0S() and flight significance >3 • e+ • electron ID. • |p| > 0.2GeV. • FRICH ≥ 0.8 • |cos | > 0.90 Ds Exclusive Semileptonic

  5. Tag invariant mass (1) KKp mode from Data Invariant Mass (GeV) Ds Exclusive Semileptonic

  6. Tag Invariant mass (2) Signal MC KK - he 50% -tag 50%  -he Signal LO HI Invariant Mass (GeV) Ds Exclusive Semileptonic

  7. unfitted Criteria of convergence: S = ∑i |di| < 1 and |c2 – c2| < 2 MM*2 = (Ecm – ED - E )2 – (- pD – p)2 5 kinematic constraints used for the kinematic fitting technique: fitted • (d1d3) • (d4) • (d5) Mass of the tag is constrained to the DS mass 50K Signal MC KKp-- he 50% -tag 50%  -he Ds Exclusive Semileptonic MM*2 (GeV2)

  8. Efficiency Determination (Signal MC) for DsXen Method presented with reference to the mode Ds+→ h e+n Efficiency defined as ratio between “double tag efficiency” (MC semileptonic decay + hadronic tag) and “single tag efficiency” (MC: hadronic tag-generic decay) (method used in hadronic branching fraction & D semileptonic branching fraction determination) eSL = ei,a÷ea KKp Single tag efficiency: ea = N(tag+gamma) ÷ NMC = N(MM*2) ÷ NMC MM*2 is obtained from a 2D fit from Liming. MM*2 (GeV2) Ds Exclusive Semileptonic

  9. Projection of the 2D fit to get the number of tags, N (MM*2) DATA Ds Exclusive Semileptonic

  10. Single -Tag efficiencies Ds Exclusive Semileptonic

  11. Tag Scaling Factors for background estimation (obtained from the MM*2 yield from Data and Generic Monte Carlo) Ds Exclusive Semileptonic

  12. Criteria of convergence: S = ∑i |di| < 1 and |c2 – c2| < 2 Signal Identification: MM2 (kinematic fitting) 8 kinematic constraints used for the kinematic fitting technique: • (d1d3) • (d4) • (d5)Mass of the tag is constrained to the DS mass • (d6) • (d7) • (d8) Sum of the mass of the two daughters of the h are constrained to its PDG value (only used for the Dshen). • Total of 8 constraints • 4 Missing variables in the fit (Energy and Momentum of the ). Ds Exclusive Semileptonic

  13. ‘Double tag ’ efficiencies KKp tag ei,a = N(MM2) ÷ Nevt_gen Signal Efficiency MM2 (GeV2) eSL = ei,a÷ea  Semileptonic signal MM2 within [-0.05 – 0.05] GeV2 Ds Exclusive Semileptonic

  14. Semileptonic efficiencies for Ds+→ h e+ne Ds Exclusive Semileptonic

  15. Run on Generic Monte Carlo (x 20 data) for method validation and for background estimate Ds Exclusive Semileptonic

  16. All evts passing our cuts Ds+he+e from Generic Monte Carlo (x20 Data) With an averaged efficiency eSL = (40.40 ± 0.28 )% And NTags = 479081 ± 2117 Nsig = 1944 ± 44 We derive BrMC(Ds→hen) = (2.55 ± 0.06)% generic-MC Br(Ds→hen) = 2.52% Ds Exclusive Semileptonic

  17. Branching fraction ofDs+e+ne We have 81.1 ± 9.0 events cut and count in the range of [-0.05 – 0.05] GeV2 Using the averaged signal efficiency eSL = (40.40 ± 0.28 )% And, the number of tags = 22320 ± 792 We derive Br(Ds→hen) = (2.284 ± 0.266)% With KKp-tag Br(Ds→hen) = (2.386 ± 0.434)% Ds Exclusive Semileptonic

  18. Other signal mode considered Ds Exclusive Semileptonic

  19. Efficiencies for other modes Ds Exclusive Semileptonic

  20. Number of backgrounds from Generic Monte Carlo Ds Exclusive Semileptonic

  21. Comparison with the Generic MC Input Ds Exclusive Semileptonic

  22. Branching fraction for Ds+ K0e+ We have 13.7 ± 3.7 events cut and count in the range of [-0.05 – 0.05] GeV2 Using the averaged signal efficiency eSL = (33.14 ± 0.26 )% And, the number of tags = 22320 ± 792 We derive Br(Ds→K0en) = (0.186 ± 0.051)% With KKp-tag Br(Ds→K0en) = (0.199 ± 0.085)% Ds Exclusive Semileptonic

  23. Branching fractionfor Ds+ he+ We have 7.4 ± 2.7 events cut and count in the range of [-0.05 – 0.05] GeV2 Using the averaged signal efficiency eSL = (22.48 ± 0.20 )% And, the number of tags = 22320 ± 792 We derive Br(Ds→hen) = (0.837 ± 0.309)% With KKp-tag Br(Ds→hen) = (1.214 ± 0.606)% Ds Exclusive Semileptonic

  24. Branching fraction for Ds+ f0e+ We have 13.1 ± 3.6 events cut and count in the range of [-0.05 – 0.05] GeV2 Using the averaged signal efficiency eSL = (46.80 ± 0.31 )% And, the number of tags = 22320 ± 792 We derive Br(Ds→f0en) x Br (f0) = (0.126 ± 0.035)% With KKp-tag Br(Ds→f0en) x Br (f0 ) = (0.143 ± 0.060)% Ds Exclusive Semileptonic

  25. Branching fraction for Ds+ K*0e+ We have 7.6 ± 2.7 events cut and count in the range of [-0.05 – 0.05] GeV2 Using the averaged signal efficiency eSL = (27.52 ± 0.23 )% And, the number of tags = 22320 ± 792 We derive Br(Ds→K*0en) = (0.185 ± 0.068)% With KKp-tag Br(Ds→K*0en) = (0.255 ± 0.128)% Ds Exclusive Semileptonic

  26. Branching fraction for Ds+ Fe+ (1) All evts passing our cuts Bgd Contribution • 0.0 < |pf| < 0.2 GeV • (b) 0.2 < |pf| < 0.4 GeV • (c) 0.4 < |pf| < 0.6 GeV • (d) 0.6 < |pf| < 0.8 GeV • (e) 0.8 < |pf| < 1.0 GeV Ds Exclusive Semileptonic

  27. Branching fraction for Ds+ Fe+ (2) * Sideband and bgd scaled subtracted Due to a very small f efficiency at pf < 0.2 GeV, we modeled the partial branching fraction by taking the fraction of f yield in the rest of the momentum intervals. Given the number of tags = 22320 ± 792 We derive Br(p>0.2GeV)(Ds→Fen) = (2.12 ± 0.35)% And Br(Ds→Fen) = (2.20 ± 0.37)% Using PDG Br(Ds→e) / Br(Ds→p) &Br(Ds→p) Compare to PDG Live Br(Ds→e) = (2.49 ± 0.28)% Ds Exclusive Semileptonic

  28. Systematic on the number of tags • The systematic error is obtained by changing the fitting schemes from the default (Polynomial 5th order): • difference in fixed BG1 shape parameters, D(BG1) • difference by increasing the polynomial order function on BG2, D(BG2) • difference by taking a change in the tail parameters (a and n) of the signal shape [a + sa and its related n] • They are added in quadratic and we have 3.59% Ds Exclusive Semileptonic

  29. Systematic on extra tracks and net charge Due to the fact that we require the tag and the signal sides have opposite charges. We use double tag to evaluate those effects Ds Exclusive Semileptonic

  30. Systematic on form-factor dependence • In generating Monte Carlo, ISGW2 is the model used. We assess the systematic uncertainty by taking the differences between ISGW2 and single pole models efficiencies. Ds Exclusive Semileptonic

  31. Systematic from background • For D*D* background, we take 0.873 ± 0.012 And see its effect on the branching fraction. • For hadronic events, we use the EID K fake rate to assess the uncertainty. Ds Exclusive Semileptonic

  32. Other systematic uncertainties • Track selection 0.3% • Hadron PID (depending on the modes) • EID, 1% • FSR, 1% Ds Exclusive Semileptonic

  33. Branching fractions results Ds Exclusive Semileptonic

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