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Mass Reconstruction Analysis in Physics Experiment with Two Constraint Methods

In this study, I employed two distinct mass constraints for the reconstruction of particles. The VertexMassConstraint was utilized for forming a composite track of Ks, while MassConstraint1 from BphysicsAnalysis posed some issues. Phil and Brad identified and corrected a bug affecting the J/Ψ mass after the first mass constraint implementation. The analysis was conducted on old dataset variations "AA" from set1 to set10. The criteria included SMT hits ≥1, kpT >0.5, χ2(K) <10, BpT >3 GeV, χ2(B) <25, and PT(J/Ψ) >4, with specific ranges for mμμ and m(Ks). Additional cuts were applied, such as |dl/σ(K)| >3 and |B decay length| >0.3 mm for mass-constrained and unconstrained scenarios. The observed values for NB0 ranged from 0.35 ± 15 to 0.88 ± 28 GeV, showcasing variations based on the constraint method used and the presence of bugs in the J/Ψ mass calculation. The B0 lifetime was also evaluated, and Monte Carlo simulations were performed to validate the findings, ensuring the accuracy of the reconstruction process.

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Mass Reconstruction Analysis in Physics Experiment with Two Constraint Methods

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  1. Bd → J/ + Ks reconstruction(d0root_xxx) • I have used two kinds of mass constraints: • VertexMassConstraint for Ks to form a composite track • MassConstraint1 in BphysicsAnalysis which now seems to be “problematic”. Phil/Brad corrected one bug (J/ mass changed after 1st mass constraint). • Data used are the old set1 to set10 of “AA”. Kin Yip March 27, 2003

  2. SMT hits1, kpT>0.5,2(K)10, BpT>3 GeV, 2(B) <25, PT(J/) > 4, 2.9< m < 3.3, 0.475<m(Ks)<0.5225, |dl/(K)|>3 Looser mass-constrained NB0 = 88 ± 28 ( GeV )

  3. One more cut: |B decay length| > 0.3 mm NB0 = 54 ± 15 mass-constrained ( GeV )

  4. Same but mass unconstrained NB0 = 60 ± 16 ( GeV )

  5. with J/ mass bug NB0 = 35 ± 15 ( GeV )

  6. B0 Lifetime (cm)

  7. Monte Carlo with J/ mass bug fixed

  8. Monte Carlo unconstrained + 3.09688 – di-_mass

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