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Charged kaon lifetime

P. Massarotti. Charged kaon lifetime. Sammary:. Events selection Reconstruction efficiency t measure Conclusions. K. vtx. K mn tag. L i. K. m. Strategy. Signal selection Self triggering muon tag K track on the signal side Decay vertex

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Charged kaon lifetime

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  1. P. Massarotti Charged kaon lifetime

  2. Sammary: • Events selection • Reconstruction efficiency • t measure • Conclusions

  3. K vtx Kmn tag Li K m Strategy • Signal selection • Self triggering muon tag • K track on the signal side • Decay vertex • Signal K extrapolated to the IP. dE/dx correction applied along the path. Li = step length Vertex efficiency and resolution functions needed wrt the proper time of the Kaon

  4. Tag self trg Tag self trg Trg eff Tag eff Why self-triggering tag?

  5. Daughter P* with kaon mass hypothesis Definition of signal sample: • Cut at 100 MeV on boost with 96% efficiency70% signal 30% “bg” (not kaon bg less than 0.2 %)

  6. Ep,xp,tp Eg,tg,xg p± xK pK lK Kmn tag tm t0 pK p0 Eg,tg,xg Reconstruction Efficiency: Neutral vertex technique • Considering only kaon decays with a p0 K X p0 X gg We lookfor the vertex asking • clusters on time: (t - r/c)g1 = (t – r/c)g2 • p0 invariant mass • agreement between kaon flight time and clusters time

  7. charged daughter kaon Efficiency measures eG = eTrK eTr sec eV • 1 2

  8. MC reco MC kine Efficency comparison MonteCarlo kine vs MonteCarlo reco  fit window definition Fit window 15 : 30 ns aG = (101.7  0.7) x10-2 bG = (-.59  3.6) x10-3 T (ns) T (ns)

  9. aTr K = (96.25  0.32) x10-2 bTr K = (.98  .14) x10-3 true MC reco MC aVTX = (101.50  0.41) x10-2 bVTX = (.83  .20) x10-3 true MC reco MC true MC reco MC Method 2: tracking & vertexing T (ns) T (ns)

  10. Paolo Massarotti Kloe general meeting 28 october 2004 New efficency comparison new cuts to select neutral and charged vertex  • fiducial volume (40 < r <150) cm , | z | < 150 cm MC reco MC kine

  11. New efficency comparison MonteCarlo kine vs MonteCarlo reco  larger fit window aG = (96.0  0.4) x10-2 bG = (-.65  1.9) x10-3 aG = (94.2  0.8) x10-2 bG = (-.06  2.3) x10-3

  12. Method 2: tracking efficency MonteCarlo kine vs MonteCarlo reco  larger fit window MC reco MC kine MC reco MC kine MC reco MC kine

  13. Method 2: tracking efficency MonteCarlo kine vs MonteCarlo reco  larger fit window aTRK = (100.4  0.2) x10-2 bTRK = (-.19  0.7) x10-3 aTRK = (100.0 0.2) x10-2 bTRK = (-.8  0.9) x10-4

  14. Method 2: vertexing efficency MonteCarlo kine vs MonteCarlo reco  larger fit window MC reco MC kine MC reco MC kine

  15. Method 2: vertexing efficency MonteCarlo kine vs MonteCarlo reco  larger fit window aVTX = (96.3  0.3) x10-2 bVTX = (-.48  .17) x10-3 aVTX = (94.3  0.6) x10-2 bVTX = (-.28  .27) x10-3

  16. Two methods compared:MC aConf = (99.3  0.9) x10-2 bConf = (.17  .39) x10-3 global product

  17. Two methods compared: Data aconf = (98.9  0.9) x10-2 bconf = (.21 .39) x10-3 global product

  18. Data and MonteCarlo compared reco MC Data

  19. Data and MonteCarlo compared reco MC Data

  20. MCtmeasure and residual evaluation T+MC = (12.36 ± 0.03) ns T+MC = (12.36 ± 0.07) ns

  21. MCtmeasure and residual evaluation T-MC = (12.36 ± 0.03) ns T-MC = (12.37 ± 0.07) ns

  22. Conclusions We have studied decay reconstruction efficiency We have to complete the measure on data (smearing factors) Work is in progress for the “time” measurement

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