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Improved Analysis of B±→J/ψp± and B±→J/ψK± Decays Using Full Data Sample

This document presents the status of the analysis for the decays B±→J/ψp± and B±→J/ψK±, focusing on results from a comprehensive data sample. Key topics include refined Probability Density Functions (PDFs), branching fraction measurements, and asymmetry analysis, based on collaboration update from September. The analysis conforms well to the signal area, addressing previous discrepancies and enhancing PDF descriptions using Monte Carlo (MC) simulations. Statistical evaluations, including systematic uncertainties, are discussed to ensure robustness of results.

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Improved Analysis of B±→J/ψp± and B±→J/ψK± Decays Using Full Data Sample

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  1. B J/y p (K) analysis on the full data sample Francesco Fabozzi, Luca Lista Università and INFN - Napoli

  2. Analysis status • September collaboration meeting • PDFs parameters from data sidebands retuned with full data sample • Still parameters from SP3 MC • Preliminary results on branching fraction and asymmetry • Fit is OK in describing the signal region • Not following data behaviour for DEp ~ –110 MeV • 1.8 s asymmetry effect in J/yK channelmostly coming from 2001 data • Now • another iteration performed • SP4 MC • Improved PDFs description F.Fabozzi

  3. DE PDF for the signal • Same DE PDF is used in J/y p, J/y K hypotheses • Fit with sum of two Gaussians • Determination of m(core)-m(tail), sigma(core)/sigma(tail), Area(core)/Area(tail) m(c)  m(t)(MeV) s(c)/s(t) A(c)/A(t) J/y mm -2.4  0.9 0.40  0.03 0.92  0.01 J/y ee -3.4  1.0 0.45  0.02 0.84  0.02 SP4 MC J/y  mm events J/y  ee events F.Fabozzi

  4. D (=DEK -DEp) PDF for the signal • Good data-MC agreement SP4 MC • Different parameters for J/y ee, J/y mm events F.Fabozzi

  5. Peaking background • Number of peaking background events are extracted from SP4 Inclusive JPsi MC (650K events) Npeaking (81.9fb-1) = 40.4  7.2 R = 0.014  0.002 mES F.Fabozzi

  6. Improved fit • In our PDFs we have always neglected the effect of the cuts defining the data sample • |DEp|<-120 MeV && |DEK|<-120 MeV • OK if sample ~ 0 near the cut values • With more statistics we need to improve PDFs including this effect Data sideband B J/y p B J/y K DEK< 120 MeV DEp> -120 MeV F.Fabozzi

  7. Improved signal PDFs • Example: PDF(DEK, D | K): • f (DEK| K)  g(D | K)if DEp> -120 MeV • 0 if DEp< -120 MeV • f PDF is the signal (core + tail) Gaussians • To characterize g we study the projection of the PDF on the D axis: • Then we obtain g: In the old fit: g(D|K) = G(D|K) F.Fabozzi

  8. Improved background PDFs (I) • Example: PDF(S, D | bkd) • Not easy as in the previous case, since both S and D PDFs are affected by the cuts • Simpler if we change variables: (S, D)  (X, Y) • Cuts corresponds to oblique lines in the (S, D) plane • Cuts correspond to vertical lines in the (X,Y) plane B A C D A B C D F.Fabozzi

  9. Improved background PDFs (II) • Characterization of X and Y PDFs • X distribution fitted with a line • Y distribution fitted with a multi-functional PDF 2nd order poly Gaussian 2nd order poly F.Fabozzi

  10. DEp projection OLD FIT NEW FIT • Sample to fit: 7854 events (4053 ee, 3801 mm) • Now the fit describes also the behavior around –110 MeV J/y  ee events OLD FIT NEW FIT J/y  mm events F.Fabozzi

  11. Branching ratio summary Np = 234  19 NK = 4521  70 Nbkd = 309859 ppee = 0.485 0.041 pKee = 0.4641  0.0077 pbkdee = 0.5941 0.0094 Br/Br (%) ee5.42  0.66 mm4.98  0.56 All 5.19  0.43 statistical error only Br. ratio in different sub-sample rpK= -0.015 F.Fabozzi

  12. Asymmetry results rpK=-0.02 Ap AK Abkd All 0.116  0.087 0.028  0.015 0.019  0.019 Run1 0.01  0.17 0.011 0.029 0.040  0.037 Run2-2001 0.30  0.14 0.038  0.024 0.017 0.031 Run2-2002 0.01 0.14 0.031  0.027 0.003  0.034 F.Fabozzi

  13. Conclusions • Complete iteration of the analysis done • All SP4 MC used • Improved PDFs both for signal and MC • Improved DEp projection • Study of the systematics is ongoing • Systematics from PDFs parametrization done • sPDF(Np)% = 2.0%, sPDF(NK)% = 0.1% sPDF( Brp/BrK )% = 2.0% • sPDF(Ap)% = 1.0%, sPDF(AK)% = 0.3% • A comparison of the fit on old and new run1 is needed • A new BAD must be released • Hopefully by the end 2002 / early 2003 F.Fabozzi

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