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Systematic Studies on Shad Measurement: First Results from Dalitz Plot Analysis

This report details the systematic studies conducted concerning shad measurements, particularly focusing on the decay process h → p+ p- p0 and the analysis of Dalitz plot parameters. The results include insights into track mass, acceptance, and Filfo systematics, with preliminary limits established for backgrounds and efficiency. We analyzed both MC samples and accumulated data, evaluating geometrical cuts and the dependence on various parameters. The findings suggest no significant dependence on Fp parameters for acceptance studies, paving the way for further explorations into decay processes and kinematic fitting.

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Systematic Studies on Shad Measurement: First Results from Dalitz Plot Analysis

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  1. FDecays Working Group Activities GENERALMEETING systematics studies concerning theshad measurement first results in h  p+ p- p0 Dalitz plot parameters h  g g g: wg background and a new upper limit Federico Nguyen - October 10th 2002

  2. GENERALMEETING Trackmass, Acceptance and Filfo studies for the shad measurement

  3. some sourcesof background can be seen in the Mtrk - distribution: -p+ p-p0:at high values of Mtrk which is Mpp2 dependent -m+ m- g:at Mtrk 104 MeV Trackmass Systematics (I) p+ p- p0 Mtrack (MeV) p+ p- g mp m+ m- g M2pp(GeV2)

  4. Trackmass Systematics (II) 2 MC samples differing only for Fp values eFZK(Mpp)  eLNF(Mpp) atthe level 2% Switched OFF PPGTAG and PPFILT

  5. Geometrical Cuts Systematics (I) we studied acceptance cuts dependence on Fp parameters by generating stand alone ppg MC samples (NTOT=106 events) with different Mr or Gr values covering the whole phase space our acceptance selection: 400 < +,-<1400 and (pt>160 MeV or |pz| >90 MeV) 00 <  < 150 or 1650 <  < 1800 E > 10 MeV there is no significant dependence on Fp parameters in acceptance studies

  6. geom [(772.6)-(770)]/(772.6) Mpp2 (GeV2) [(772.6)-(780)]/(772.6) Mpp2 (GeV2) Mpp2 (GeV2) Geometrical Cuts Systematics (II) dependence onMr - we fixed the other parameters

  7. [(143.7)-(140)]/(143.7) Q2 [(143.7)-(150)]/(143.7) Q2 Geometrical Cuts Systematics (III) dependence onGr - we fixed the other parameters geom Mpp2 (GeV2) Mpp2 (GeV2) Mpp2 (GeV2)

  8. Filfo Systematics (I) FILFO/par=5: ~ 2000 refiltered files 6 pb-1 from different periods of 2001 DATA taking • Filfo efficiency is evaluated from DATA by reprocessing RAW • without using Filfo as a filter • to overcome the long • reconstruction time, a prefilter, based on CALORIMETER and PATTERN RECOGNITION, is used, then TRACK, VERTEX modules are called... Mpp2 (GeV2) errors ~0.5-1% per bin Mpp2 (GeV2) Overall efficiency: DATAFILFO, SMA= (94.82±0.07) %

  9. Filfo Systematics (II) • signal events vetoed by FILFO/par=5 • by the following: • Bhabha-filter (83.5%) • Cosmic-filter (13.9%) • Machine Background filter (4.3%) 4734 events BHABHA[3955events] COS[659 events] MB[205 events] Mpp2 (GeV2)

  10. Filfo Systematics (III) FILFO/par=5: 2  105 stand alone MC events • we wanted to know the difference in applying Filfo at the beginning or at the end of our analysis chain • resulting systematic correction: •  = (-0.71 ± 0.07)% Overall efficiency (Filfo at first): MCFILFO, SMA= (96.66±0.07) % Mpp2 (GeV2) systematic Filfo checks have been performed we plan to study Filfo changes in different periods of DATA taking Mpp2 (GeV2) Overall efficiency (Filfo at the end): MCFILFO, SMA= (97.37±0.07) %

  11. GENERALMEETING f  h g, h  p+ p- p0: resolution, fit procedure and results

  12. Dalitz Plot Parameters: Definition Ti kinetic energy of the pi Q mh - 2mp+ - mp0 usual decay rate in terms of slope parameters: G(h  p+ p- p0 )  |M(X,Y)|2 |M(X,Y)|2  1 + aY + bY2 + cX2

  13. Dalitz Plot Parameters: Resolution (I) Y resolution has been obtained by using 1.3105 MC events it can be estimated either from p or from gg (fromp0) score = 0.034 score = 0.042

  14. Dalitz Plot Parameters: Resolution (II) score = 0.028

  15. as a 1st approximation b  c  0, , that has to be fitted on: Fit Procedure and Results (I) where: N(X,Y) = # of events in the Dalitz plot e(X,Y) = efficiency (from an independent MC sample) PS(Y) = phase space as a function of Y bins

  16. Fit Procedure and Results (II) 16 pb-1from 2000 DATA have beenstudied (the same selection for the mixing angle analysis,Kloe Memo 266) dN/dY ~ 1 + aY Y

  17. Fit Procedure and Results (III) resolution studies have been optimized, 1st glance at DATA shows sensitivity to the quadratic slope parameter dN/dY ~ 1 + aY + bY2 Y

  18. GENERALMEETING f  h g, h  g g g: selection cuts, possible background and preliminary limit

  19. after kin. fit kinematic fit has been studied on MC (Ntot=3104 events) before kin. fit Eg (MeV) Eg (MeV) Analysis Requirements Pre-selection: 4 prompt clusters Angle between two clusters > 15° Etot(clusters) > 900 MeV; Ptot < 110 MeV • Final Selection: • Pkin-fit(2>20) > 0.01 • |M - 140| > 30 MeV • E vs. cosplane cut • |Mggg– 550|< 45 MeV

  20. e+ e- w g1 4 p0 g2 Background Problem w peak  Mrecoil of g1 (MeV) inconsistent with MC estimated background 59events perhaps a missing background: wg can be rejected by p0 cut, still we must know the tails g1 non p0 least energetic g Mgg (MeV)

  21. Preliminary Results on 2001 DATA from MC: sGauss = 13 MeV PAW raw fit: a+bx+cx2+Nsignal*Gauss Mggg (MeV) Mggg (MeV) Nsignal = 9 26, corresponding to 616 events out of 142 pb-1 Nupper (90% C.L.) = Nsignal + 1.28*sNsignal = 42, eTOT = 21% BR(hggg) < Nupper/(L*sF*BR(f hg)*eTOT) = 3.5 10-5

  22. Summary and Outlook shad: NO significant Fp parameters dependence both in acceptance and trackmass, filfo efficiency has been studied, we started evaluating trackmass efficiency from DATA. h  p+ p- p0 : resolution and fit procedure have been checked, work ahead: genuine 2D fit, 2001-2002 DATA analysis. h  g g g: wg background has been studied, but a MC code is needed, reachable limit (~ 500 pb-1): BR(h  g g g) < 2 10-5 .

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