Malcolm John

Abstract:

The branching fractions and CP violating charge symmetries for B + → K0π+ and B0→K 0π0 were measured. The decays values for B 0→K̄0K0 and B0→K 0K̄0 were investigated. The upper limits on their branching functions were set at 2.5×10-6 and 1.8×10 -6 respectively, at the 90% CL. It was found that the branching fraction were consistent with previous measurements of the same quantities, but had nearly twice the statistical precision.

Abstract:

CP, T, and CPT violation in B0B̄0 oscillation and limits on the decay-rate difference of neutral B mesons were analyzed. Data and Monte Carlo samples were used to validate the analysis technique. It was found that the limit on CP and T violation in oscillations is independent of and consistent with the measurement based on an analysis of inclusive dilepton events. It was suggested that the fits to data subsamples selected by tagging category, running period, and Brec decay mode give consistent results.

Abstract:

A study of the decay B- → D*0K*- based on a sample of 86 × 10 6 υ(4S) → BB̄ decays was presented. The measurement was found to be 2.5 times more precise than previous results. The measurement was based on heavy quark effective theory. The longitudinal polarization fraction of this decay was also measured.

Abstract:

The physical characteristics such as mass and total width of ηc meson were analyzed in two-photon interactions. The hyperfine separations were found to be directly related to spin-spin interactions. The momenta of charged particles were measured and their trajectories reconstructed with two detector systems which were located in 1.5 T solenoidal magnetic field. The charged particle identification was provided by detector of internally reflected Cherenkov light. The mass resolution was determined by fitting the distribution of difference between reconstructed mass and generated mass to Gaussian function.

Abstract:

A search for the lepton-flavor-violating (LFV) decay of the tau into three leptons was performed by using 91.5 fb-1 of data collected at an e+ e- center-of-mass energy around 10.58 GeV with the BABAR detector at the SLAC storage ring PEP-II. It was shown that the most stringent limit on FLV was B(τ → μγ) < 3.1 × 10 -7 at 90% C.L., in tau decays. The efficiency of the selection for signal events was estimated with a Monte Carlo (MC) simulation of LFV ray decays. The simulated tau-pairs events including higher-order radiative corrections were generated using KK2F with one tau decaying to three leptons with a three-body phase space distribution.