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Study of the semileptonic decays at 4170 MeV

Study of the semileptonic decays at 4170 MeV. Koloina Randrianarivony Marina Artuso ( Syracuse University ). Motivations. Apply our techniques to other semileptonic decays. Study the modes that haven’t been seen yet. Analysis Techniques. e+ e- (1 -- ). D s - (D s -* ).

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Study of the semileptonic decays at 4170 MeV

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  1. Study ofthe semileptonic decaysat 4170 MeV Koloina Randrianarivony Marina Artuso (SyracuseUniversity)

  2. Motivations • Apply our techniques to other semileptonic decays. • Study the modes that haven’t been seen yet.

  3. Analysis Techniques e+ e- (1--) Ds-(Ds-*) Ds+* (Ds+) + ... TAGGED SIDE: K+K-p- KsK- p- (+-)p- F(K+K-)- +-- K*K*(KsK-+-) - SIGNAL SIDE (K+K-) e+ , K*0(K+-) e+,K0(+-)e+n And '(+-) e+ + CC Event The same 8 modes as in Ds+ →+ CBX 06-36

  4. Selection criteria • Data sample • ~310 pb-1 at ~4170 MeV • 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). • K*0 K-p+ • PID for both Kaon and Pion. • | K*0Mass-PDG|< Г=0.050 GeV • f  K+K- • PID for both Kaons. • | f Mass-PDG|< 2x Г=0.01 GeV K0 Use standard VXFit Package. ' Mass constrained fit for . Add 2 opposite charged PID Pions. • e+ • electron ID. • |p| > 0.2GeV. • FRICH ≥ 0.8

  5. MM*2 = (Ecm – ED - E )2 – (- pD – p)2 Cut on MbcЄ[2.015, 2.067] Alpha and N are fixed from fully reconstructed Ds-Ds*+ events where one Ds is ignored (CBX 06-36) Look at the invariant mass of the tags and cut on 2-2.5 depending on the modes Look for any extra photon and select events within ± 2.5 σ Signal MC KK - K*e 50% -tag 50%  -he These are our number of tags MM*2 (GeV2)

  6. MM*2 per modes for Ds→ K*0e SIGNAL MC Number of Events MM*2 (GeV2)

  7. MM*2 (Data) The same number of tags as Nabil: 18645 ± 426 Number of events MM*2 (GeV2)

  8. MM2 On the signal side Fit with a 2 gaussian Get ± 2.5 effective sigma  = f11 + (1-f1)2 # of semileptonic events, the effective sigma will be used for the rest of the modes to get the sum. Signal MC KK - K*e 50% -tag 50%  -he MM2 (GeV2) Kinematic fitting is used on tag and signal sides

  9. Ds+→ K*0e+ From signal side From sidebands MM2 (GeV2) Use of sideband subtraction GENERIC MC

  10. DsK*0eEfficiencies We get the weighted average SL efficiency = (28.34 ± 0.27)%

  11. Using our efficiencies and Comparison with the generic MC for DsK*0e With NTags = 187158 ± 1052 NSignal = 35 ± 6 And SL = (28.34 ± 0.27)%, we get Generic-MC Br (Ds+ → K*0(K)e+) = (8.6 ± 1.6)% Input BrMC(Ds+ → K*0(K)e+) = 7 x 10-4 * The number of events are sideband subtracted

  12. MM2 for Ds+ → K*0(K)e+(Data) K+- mass Є [0.846, 0.946] GeV 7 signal events 0 background from the sidebands Number of events MM2 (GeV2)

  13. ISGW2 SLPOL Dse Analysis Comparison ISGW2 model vs.Simple Pole Model P (GeV)

  14. Dse Efficiencies Semileptonic efficiencies 

  15. Comparison with Generic MC for Dse Using our efficiencies and With NTags = 187158 ± 1052 Input Generic Br(Ds→e) = 2.02 % * The number of events are sideband subtracted

  16. MM2 for Ds+ → (KK)e+(Data) K+K- mass Є [1.010, 1.030] GeV 47 signal events 0 background from the sidebands Number of events MM2 (GeV2)

  17. DsK0eEfficiencies We get the weighted average SL efficiency SL = (33.15 ± 0.24)%

  18. and Using our efficiencies Comparison with the generic MC for DsK0e With NTags = 187158 ± 1052 NSignal = 52 ± 7 And SL = (33.15 ± 0.24)%, we get Generic-MC Br (Ds+ → K0()e+) = (0.23 ± 0.03)% Input BrMC(Ds+ → K0()e+) = 0.2% * The number of events are sideband subtracted

  19. MM2 for Ds+ → K0()e+(Data) +- mass Є [0.48765, 0.50765] GeV 10 signal events 8 background from the sidebands Number of events MM2 (GeV2)

  20. Ds'e Efficiencies We get the weighted average SL efficiency SL = (21.64 ± 0.26)%

  21. Using our efficiencies and Comparison with the generic MC for Ds'e With NTags = 187158 ± 1052 NSignal = 56 ± 7 And SL = (33.15 ± 0.24)%, we get Generic-MC Br (Ds+ → '()e+) = (0.8 ± 0.1) % Input BrMC(Ds+ → '()e+) = 0.9% * The number of events are sideband subtracted

  22. MM2 for Ds+ → '()e+(Data) K+- mass Є [0.950, 0.964] GeV 5 signal events 0 background from the sidebands Number of events MM2 (GeV2)

  23. Branching Fractions from Data (1) With a number of tags = 18645 ± 425 Due to a very small efficiency at p< 0.2 GeV, we modeled the partial branching fraction by taking the fraction of  yield in that range to  yield in the rest of the momentum intervals.We estimate it as: Br(p <0.2 GeV) (Ds→e) = (0.8 ± 0.8 (syst))% Br(Ds→e) = (2.6 ± 0.3)% Compare to PDG 06 Br(Ds→e) = (2.4 ± 0.4)%

  24. Branching Fractions from Data (2) With a number of tags = 18645 ± 425 and

  25. Summary and Predictions • Br(Ds→e) = (2.6 ± 0.3)% • Br(Ds+ → K*0(K)e+) = (0.19 ± 0.07)% • Br(Ds+ → K0()e+) = (0.47±0.15)% • Br(Ds+ → '()e+) = (0.71±0.32)% And with Br(Ds+ → e+) = 3.3% We have Br(Ds+→Xe+)excl = (7.27 ± 0.84)% With a mean life τ = 0.5 ps, we get Г = 0.1294 ± 0.0169 ps-1 Г+ = 0.1551 ps-1 x 0.5ps = 0.077  7.7%

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