1 / 28

“Final” Γ(Ke3) / Γ(pipi0) Γ(Kmu3) / Γ(pipi0) Γ(Kmu3) / Γ(ke3)

“Final” Γ(Ke3) / Γ(pipi0) Γ(Kmu3) / Γ(pipi0) Γ(Kmu3) / Γ(ke3). Anne Dabrowski Northwestern University NA48/2 Analysis Meeting 27 October 2005. Outline. Introduction Acceptance, particle ID, Trigger and Backgrounds Table of Systematic Results What we get extract from this result:

oliver
Download Presentation

“Final” Γ(Ke3) / Γ(pipi0) Γ(Kmu3) / Γ(pipi0) Γ(Kmu3) / Γ(ke3)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. “Final” Γ(Ke3) / Γ(pipi0) Γ(Kmu3) / Γ(pipi0) Γ(Kmu3) / Γ(ke3) Anne Dabrowski Northwestern University NA48/2 Analysis Meeting 27 October 2005

  2. Outline • Introduction • Acceptance, particle ID, Trigger and Backgrounds • Table of Systematic • Results • What we get extract from this result: • Branching fractions for Ke3, and Kmu3 • Kmu3/Ke3 test of theory given measured form factors • Vus • Extra Studies • Source of the acceptance change due to generating MC with real gammas • KLOE vs. Ginsberg + PHOTOS MC revisited • Conclusion

  3. Measurement of Ratios Ratio(ke3/pipi0); Ratio(kmu3/pipi0) A. Dabrowski, October 27 2005

  4. Principle of the Analysis • Track • 1 pi0 • Kaon mass cut • Particle ID • electron E/P > 0.95 • pion E/P < 0.95 • muon ID using muon Veto • (few other kinematical cuts ... can refer to my other talks for details) Ratio(ke3/pipi0); Ratio(kmu3/pipi0) A. Dabrowski, October 27 2005

  5. Input needed to extract the ratios • Acceptance • Particle ID efficiency • Trigger efficiency • Number of events in Data • Background substraction, done in both signal and normalisation Ratio(ke3/pipi0); Ratio(kmu3/pipi0) A. Dabrowski, October 27 2005

  6. Summary Table of inputs for the ratios Change in acceptance of 1.7% since ICHEP due to effect of real gammas in Ke3 MC Ratio(ke3/pipi0); Ratio(kmu3/pipi0) A. Dabrowski, October 27 2005

  7. Main Contributions to the background Neutrino mass cut sensitive to background when pion decays Ratio(ke3/pipi0); Ratio(kmu3/pipi0) A. Dabrowski, October 27 2005

  8. Main Changes to analysis compared to ICHEP result Reprocessed data  energy baseline correction Alphas and Beta corrections Neutral Vertex method with full Blue Field and projectivity corrections CMC005 (CMC003 at ICHEP) Now simulate real gammas in the ke3 (kmu3) MC ; in ICHEP we used just Ginsberg for ke3 (kmu3) Ratio(ke3/pipi0); Ratio(kmu3/pipi0) A. Dabrowski, October 27 2005

  9. Difference when varying the linear model by +- 1 σ on the form factors Contributions to the systematic of ke3/pipi0 We have used Linear form factor model as our reference, but we are ready to use quadratic, or pole model.

  10. Contributions to the systematic of kmu3/pipi0 Form factor model systematic also dominated by the quadratic. Reference parameterisation is linear – ready to switch to pole or quadratic if necessary

  11. Summary of results

  12. Ratio kmu3/ke3

  13. Summary of experimental Results

  14. Extraction of Branching Ratios The uncertainty is dominated by the pipi0 branching fraction. Using the PDG 2004 value for the branching ratio of pipi0 0.2113 +- 0.0014, Recall PDG: Br(Ke3) = 0.0487 +- 0.0006 Br(Kmu3) = 0.0327 ± 0.0006 Recall ICHEP: Br(Ke3): 0.0514 +- 0.0002 (stat) +- 0.0006 (sys)

  15. kmu3/ke3 predicted by theory

  16. Extraction of Vus f+(0) Inputs done for the linear form factor model, but we have available the phase space integrals for the quadratic and the pole form factor models.

  17. Extraction of Vus

  18. Extraction of Vus

  19. Combined Vus Result for NA48/2 Using f+(0) = 0.9821 +- 0.008 +- 0.002 for K± * (compared to 0.961 +- 0.008 for K0) |Vus|unitarity was calculated assuming unitarity and given |Vud|=0.9740 ± 0.0005 ** and |Vub| small *** * H Leutwyler and M Roos, Z. Phys C 25 (1984) 91. ** (A Czamecki, W.J. Mariano and A Sirlin phys Rev D 70 (2004) 093006 hep-ph/0406324) *** (K Hagiwara et al, Physical Review D 66 (2002))

  20. Additional Studies • Effect of real gammas in the Ke3 MC simulation Ginsberg vs (Ginsberg + PHOTOS) (KLOE) • Ginsberg + PHOTOS compared to KLOE

  21. Effect of real gammas in Ke3 MC • Acceptance effect of 1.7% was seen between Ginsberg (no real gammas simulated) and Ginsberg + PHOTOS (or KLOE) (real gammas simulated). • The improvement in the DATA/MC reflected that real gammas did improve the invariant mass of epi0 distribution • But effect in the change in acceptance needed to be investigated because we do not cut on the epi0 variable

  22. Effect of real Gammas in MC – Neutrino mass reconstruction • The source of this effect is due to the neutrino mass cut (-0.012 : 0.012 ) GeV ^2, where the neutrino is mis-reconstructed due to the wrong gamma being selected to make the pi0 • Visible differences in the tail of the neutrino mass distribution for ke3 for the two MC’s .

  23. Effect of real Gammas in MC – Neutrino mass reconstruction • If one removes this cut, the acceptance between Ginsberg and Ginsberg + PHOTOS agree Without the cut difference goes away

  24. DATA/MC Ginsberg + PHOTOS is MC of choice Better description of the tails when real gammas are simulated

  25. Effect of removing this Neutrino Mass cut in Ke3 • This neutrino mass cut is powerful in removing background. • Releasing cut, background increases by X25 to • K+ (0.411 +- 0.022) % • K- (0.457 +- 0.031) % • And the ratio ke3/pipi0 is absolutely stable. • This background is well understood, and can be easily subtracted. (and it is still small) • Propose to remove this cut from the official cut … Now that we understand the background so well, it serves no purpose

  26. What about for Kmu3? • Firstly, there was almost no acceptance change when comparing Ginsberg and Ginsberg+PHOTOS. • The neutrino mass for kmu3 has even tails, and is almost Gaussian. • The background in kmu3 is already X20 higher than for ke3 (pions decaying into muons), and releasing this cut would increase the background to about 4%. • Propose leaving this cut in for kmu3 analysis

  27. Report on KLOE vs Ginsberg+PHOTOs MC ke3 Cambridge •  from Cambridge meeting, showed ridges in KLOE/Ginsberg MC •  After checks with C. Gatti (From KLOE), numerical solution solved. Still a slope in the Dalitz plane. This slope will be investigated. Now

  28. Conclusion • Results of the draft version of the paper were shown today. • I propose to release the neutrino mass cut in ke3 for final version on the paper, and to leave the neutrino mass cut in for kmu3. • Numerical MC issue with KLOE vs. Ginsberg has been resolved. • MC being used at the moment • Ke3 Ginsberg + PHOTOS (KLOE also available) • Kmu3 Ginsberg + PHOTOS (KLOE MC does not have the lambda0 term of the matrix element yet) • Pipi0 KLOE

More Related