Branching Fraction Measurement of B⁰ → K∗⁰(K⁺ π⁻) J/ψ (ℓ⁺ ℓ⁻) Decay in Simulated Events with Belle II Detector

Rattan, Hitesh (2022) Branching Fraction Measurement of B⁰ → K∗⁰(K⁺ π⁻) J/ψ (ℓ⁺ ℓ⁻) Decay in Simulated Events with Belle II Detector. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Hitesh Rattan (17MS049)) 17MS049_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

This thesis presents an analysis of the neutral mode of B → K∗ J/ψ. The study have been performed on Monte Carlo(MC) simulations of of Belle II, SuperKEKB accelerator complex at KEK Laboratory, Japan. For the analysis 1 ab−1(tentatively) equivalent of genric MC sample is taken from MC13a campaign and the beam background (BGx1) is taken from the Geant4 simulation of the detector. The aim of this study is to measure the branching fraction of the neutral mode decay B → K∗ J/ψ where J/ψ subsequently decays to pair of leptons. The decay B → K∗ J/ψ arise from the quark-level process b → c c s, which have large decay rates and serves as a good control sample to the decay B → K∗ ℓ⁺ ℓ⁻ with the same final state particles. The branching fraction of B⁰ → K∗⁰J/ψ(→ ℓ⁺ ℓ⁻) is found out be 8.171 ± 1.212(stat.) ×10⁻⁵ A toy Monte Carlo study is done to check for the presence of any bias. The mean and variance of the pull distribution are found to be consistent with 1 and 0, respectively, within the uncertainty. Hence, the fit model is found to be free from any bias. v.

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