BR(K S  gg) Analysis update

1. BR(KSgg) Analysis update M. Martini and S. Miscetti 14/12/2006

2. Talk Layout • First sample of MC 2004 analyzed • • MC 2004 integrated luminosity, 214 pb-1 • • Production stopped since some AFS problems + • token expiration (slowest queues for users), we will • restart the production asap • Improved MC simulation of QCAL following • DATA (adding accidental, first fix to efficiency…) • MC-DATA EMC energy scale adjusted

3. Monte Carlo sample • Total integrated luminosity: To extract the BR, we use this MC sample summing 2001-2002 and 2004-2005 production

4. Data 2001-2002 fit results •• DATA -- MC all Signal Background Fit Data with the complete MC sample

5. Data 2004-2005 fit results •• DATA -- MC all Signal Background Fit Data with the complete MC sample

6. BKG shapes resulting from 04-05 fit MC old MC all sample Comparison between old and new MC sample for the BKG shape

7. Fit results Total MC sample Old MC sample BR obtained compatible with previous results but… We still need more MC statistics to decrease uncertainty

8. Data-MC energy scale MC01-02 MC 2001-2002 2g, BKG •• Data -- MC 4g, KS2p0 Before scale calibration

9. Data-MC energy scale MC01-02 MC 2001-2002 2g, BKG •• Data -- MC 4g, KS2p0 After scale calibration

10. Data-MC energy scale MC04 MC 2004 2g, BKG •• Data -- MC 4g, KS2p0 Before scale calibration

11. Data-MC energy scale MC04 MC 2004 2g, BKG •• Data -- MC 4g, KS2p0 After scale calibration

12. Data-MC energy scale Before We have a not significant effect on Mgg for KSgg signal events from MC After

13. Data-MC energy scale •• DATA -- MC all Signal Background Fit Data with the adjusted MC sample

14. DATA-MC energy scale We obtain an higher BR using the calibrated sample (~10% more) but we have a slightly worst fit….

15. DATA-MC energy scale Data 2004-2005 Not Calibrated FCN = 72.3 c2 = 1.64

16. DATA-MC energy scale Data 2004-2005 Calibrated FCN = 80.3 c2 = 1.82

17. QCAL simulation DTQCAL: Comparison between Data and the standard MC simulation of QCAL We improve the simulation considering 3 different contributions in MC

18. QCAL simulation 1 component: Standard simulation + Gaussian smearing + Offset to center T-R/c

19. QCAL simulation 2 component: Accidental hit rephased with RF

20. QCAL simulation 3 component: When there are MC photons hitting QCAL but there are not reconstructed hits, we had the % of losses found in data by using a gaussian distribution of DT

21. QCAL simulation Final comparison: Data MC QCAL simulation

22. QCAL simulation – Statistical variation DATA Mgg after QCAL veto Old simul. New simul. MC After QCAL veto, we now have the Adjusted Qcal simulation which follows much better the vetoed fraction in data R = 0.34/0.48 = 71% vs 69.5% from plot!

23. QCAL simulation •• DATA -- MC all Signal Background Fit Data with the adjusted QCAL MC sample As example: Data 01-02 MC 01-02

24. QCAL simulation No QCAL sim QCAL sim Comparison between adjusted and not adjusted MC sample for the BKG shape

25. QCAL simulation The larger error is due to the reduced statistics after QCAL veto. The value of the BR is not modified using the simulation above.

26. Conclusions • Using the new + old MC production we obtain a compatible result • for the BR. • We started using the MC scale calibration for EMC .. OK for 01- • 02 .. In progress for 04-05. Final BR will be estimated after fixing • the scale. Systematics will follow. • The improved QCAL simulation on MC gives compatible results • and will be used as systematic • To be done: • Prepare a significant MC 2004 sample to decrease BR uncertainty • Process the few missing pb-1 of data (200-300) • Meeting with referees to decide paper strategies • Start writing the memo