Measurement of f in h g with p + p - 7 g final state

1. Measurement of f in hg with p+ p- 7g final state Camilla Di Donato

2. Outline of the talk • Motivations of this analysis • The data sample • Event Selection • Systematic checks • Results • Conclusions [see C. Di Donato, KLOE Memo 327]

3. Motivations of this analysis • BR(fhg) can probe the ss and gluonium content of h • The ratio R= BR(fhg)/BR(fhg) can be related to the h-h mixing parameters and determine the mixing angle in the flavor basis P, the best parameter for a description of the mixing • The two mixing parameter, has emerged from EcPT and phenomenological analyses, in the flavor basis are equal apart from terms which violate OZI-rule

4. The data sample • MC RAD04: the clusters are weighted using the correction by S. Miscetti, optimized to solve the bug of over number artificial accidentals; we use Spadaro-Palutan efficiency curve for clusters (thanks to Simona G.) • DATA: 2001-2002 run # 17874-26965 Lint=427 pb-1

5. Signal & Background • Two channel can contribute to the signal f  hg [BRPDG= (6.2±0.7)·10-5] hp+p-h with hp0p0p0 (charged [BR=(13.9±0.5)%]) hp0p0h with h p+p-p0 (neutral [BR=(4.6±0.3)%]) • Background: f KSKL KS  p+p-; KL  p0p0p0 KS p0p0; KL  p+p-p0 KS  p+p-g; KL  p0p0p0

6. Barrel Ecap West Barrel Ecap West First level selection: h Trigger, Filfo and EVCL give a first level selection: • Trigger efficiency very high: 99.7% (crg); 99.9%(ntr) • Filfo efficiency for triggered events: 100% • EVCL efficiency for triggered events: 57.9% (crg); 61.45% (ntr) Effects on the analysis • Trigger: 100% • EVCL: 99.07% (crg); 97.03% (ntr)

7. Sample preselection and kinematic fit Acceptance cut: • 7 neutral clusters in time window, |Tclu-Rclu/c| < min(5sT,2ns ), with Eclu > 10 MeV and qclu> 21º • One charged vertex near IP r < 4 cm & |z| < 8 cm with two opposite charged tracks Kinematic fit: • requiring 4-momentum conservation and the promptness of g’s ( TcluRclu/c = 0 )

8. Analysis cut • c2/Ndf< 4.54 • KtagVeto: no double writing stream events, but only radiative one reject events from neutral kaon stream as KS  p+p-KL  p0p0p0and KS  p+p-g; KL  p0p0p0 • Eclu>20 MeV  reject events from KS  p0p0KL  p0p+p- • cosqp+p-0.84  reject events from multi-photons final state events with photon conversion

9. c2/Ndf cut The study of the ratio N/e to choose the cut MC data

10. Eclu>20 MeV  reject events from KS  p0p0KL  p0p+p-

11. cosqp+p-0.84

12. The h events •  hgrad… gradp+p-p0p0p0  gradp+p-6g

13. The h events From M(p+p-6g) to M(h) invariant mass

14. Signal h • We select also f  hg decay [BRPDG=(1.301±0.024)%] with hp0p0p0; we have 7 g in the final state. It’s background free We start from the selection done by F.A. and F.P.: • one prompt neutral cluster with 320MeV< Eg < 400 MeV and Ep+ + Ep-< 550 MeV; • same selection as for h ;

15. A normalization sample: h Trigger, Filfo and EVCL give a first level selection: Effects on the analysis • Trigger: 100% • Filfo-EVCL: 99.27% Sample preselection and kinematic fit Acceptance cut: • 7 neutral clusters in time window, |Tclu-Rclu/c| < min(5sT,2ns ), with Eclu > 10 MeV and qclu> 21º • No tracks from IP Kinematic fit: • Requiring 4-momentum conservation and the promptness of g’s ( TcluRclu/c = 0 )

16. The h events •  hgrad gradp0p0p0  grad6g Mh (MeV) Eg (MeV)

17. Systematic checks • Filfo-EVCL: data selected from raw without Filfo-EVCL • TRK-VTX: data from raw filtered with filfo/par=1 to select a sample for study of f p+ p- p0, the control sample to check efficiency • Check of MonteCarlo stability • Uncertainty on the c2/Ndf cut • Correction due to interference between amplitudes A(f h(h)g) and A(r h(h)g)

18. Filfo-EVCL • Using 40pb-1 selected with a minimum bias procedure and without EVCL and Filfo (see kloe memo 365) we measure the efficiency on data 1% from efficiency evaluation as systematic contribution to the uncertainty With KtagVeto(EVCL) With Ep++Ep-<500MeV

19. TRK efficiency • Cut on clusters Eclu<400 MeV • 2 prompt neutral clusters qclu>25° & Eclu>50 MeV • |Mgg – Mp|<20 MeV • 2 clusters 0.8<b<0.95 & Eclu>100 MeV • one track qtrk>40° & 200MeV<Ptot<400 MeV  We look if there is a track in a cone of 35° around Pmiss

20. TRK efficiency + MC + Data Background contamination at level of 1%

21. TRK efficiency etrk(Data)/etrk(MC) = 0.992±0.003  1%

22. VTX efficiency • Cut on clusters Eclu<400 MeV • 2 prompt neutral clusters qclu>25° & Eclu>50 MeV • 100MeV < Mgg < 170 MeV • two tracks qtrk>40° & 50MeV<Ptot<400MeV • 850 MeV<Etot<1200MeV  We look for a vertex as a function of the minimum momentum

23. VTX efficiency + MC + Data Background contamination at level of 1.5%

24. VTX efficiency evtx(Data)/evtx(MC) = 0.990±0.001  1%

25. Check of MonteCarlo stability

26. Interference between amplitudes A(f h(h)g) and A(r h(h)g) • Has been evaluated in the Born approximation • Take into account also radiative corrections at the cross section

27. Interference between amplitudes A(f h(h)g) and A(r h(h)g) s Kr run

28. Results

29. Results Systematics are dominated by knowledge of h,h’ branching ratios Previous KLOE results: Phys. Lett. B541 (2002) 45-51

30. Pseudoscalar mixing angle Using the Bramon approach [A.Bramon et. al. Eur. Phys. J. C7, 271(1999)] we extract mixing angle: • stat. uncertainty: mc extraction of R with Gaussian distribution • syst. unc.: mc extraction of R with flat distribution • th. unc.: difference between angle extractions using different values for parameters.

31. Stat. and syst. uncertainty • Monte Carlo extraction of R with Gaussian distribution using the statistical error as sigma and then evaluating the 68% confidence interval on P • Monte Carlo extraction of R with flat distribution R±DR; we get a flat distribution of P and we take the systematic as the half interval of the distribution

32. Theoretical uncertainty • VP Wave function overlaps [A.Bramon et. al. Phys. Lett. B503, 271 (2001)]: ZNS=0.91±0.05; ZS=0.89±0.07; ZNS/ZS =1.02±0.10  ±10%  maximum variation P =±0.3º • ms/m= (1.24-1.45)  maximum variation P=±0.5º Theo. unc. P=±0.6º

33. Gluonium content The meson h is a good candidate to have a gluonium content Gluonium content means We have 3 constraint in the plane:

34. Gluonium content We have 3 constraint We published in 2002

35. Gluonic content of h´ Another constraint on the Y2-X2h´ plane can be added by measuring the decay h´→wg[Kou PRD 63 (2001) 54027] BR(h´→wg) measured by KLOE with 2.5 fb-1 (stat. error only) Present situation

36. Conclusions • 2001-2002 data analysis in kloe memo 327 • All checks asked by referee has been done • Agreement with published branching ratio • We get a very accurate measurement of the BR(fhg) and the determination of pseudoscalar mixing angle with uncertainty less then 1º • The work is over

37. Conclusions II • Theoretical error to Kr dominated by G

38. Acknowledgement • Mille grazie ai miei referee Simona e Paolo che oltre a verificare il mio lavoro, mi hanno aiutata a chiudere l’analisi e il memo. • Grazie a Stefano, Matteo e Tommaso per il loro contributo per la parte di clustering, a Federico per la selezione da raw dei f p+ p- p0e a Fabio per i suggerimenti nello studio del contenuto gluonico e non solo • Grazie a Tiziana per il suo sostegno e a Chiara che questa notte mi ha fatto dormire un po’ più del solito

40. Background evaluation The background study required an huge amount of events: an ad hoc production has been done with run condition from 2000 data On the other hand we have the MC production with the simulation of right run condition Systematics due to background subtraction has been evaluated from comparison between results from official MC w.r.t. the ad hoc production: Background at level of 8.5% for official MC Background at level of 9.2% for ad hoc production We say that the background is at level of (9.2±0.7)%, which means, for the analysed sample, Nbg = 345 ±6stat ±28syst

41. What we measure? The ratio of the two branching ratio: