A kinematically complete measurement of K^+ \to \pi^+ \pi^0 \pi^0 decays

In a kinematically complete setting, the decays of stopped were measured. In the frame work of the Weinberg polynomial expansion, the coefficients up to quadratic terms were deduced. The results are in good agreement with previous measurements and consistent with CP conservation expectations. The empirical rule is violated. Received: 16 October 1999 / Published online: 27 January 2000     

Effects of Final State Interactions in Pure Annihilation Decay of B^{0}_{s}\rightarrow\pi^{0}\pi^{0}

We investigate the effects of final state interactions (FSI) contributions in the nonleptonic two body $B^{0}_{s} \rightarrow \pi^{0}\pi^{0}$ decay. The short distance interaction amplitude is calculated by using the annihilation diagrams and a tiny branching ratio is obtained, then the long distance amplitude is considered and calculated within FSI effects. For contributions of FSI, the ρ ⁰ ρ ⁰, π ⁺ π ^?(ρ ⁺ ρ ^?), K ⁺ K ^?(K ^+? K ^??) and $K^{0}\bar{K}^{0}(K^{0*}\bar{K}^{0*})$ are produced for intermediate states, in this case the π ⁰, π ^?(ρ ^?), K ^?(?) and $\bar{K}^{0(*)}$ mesons are exchanged. The absorptive part of the diagrams is directly calculated and the dispersive part of the rescattering amplitude can be obtained from the absorptive part via the dispersion relation. The imaginary and real parts of the amplitudes are summed over all intermediate states. The predicted branching ratio of $B^{0}_{s} \rightarrow \pi^{0}\pi^{0}$ is 0.69×10^?8 in the absence of FSI effects and it becomes 1.86×10^?4 when FSI contributions are taken into account, while the experimental result is less than 2.1×10^?4.     

The neutral kaon decays to \pi^+ \pi^- \pi^0: a detailed analysis of the CPLEAR data

A detailed analysis of neutral kaons decaying to is presented based on the complete data set containing half a million events. Time-dependent decay rate asymmetries are measured between initially tagged and and for different regions of the phase space. These asymmetries, resulting from the interference between the CP-conserving decay amplitude of and the decay amplitude of – either CP-violating or CP-conserving – allow the determination of the parameters (CP-violating) and (CP-conserving), and also of the main isospin components of the decay amplitude. The branching ratio of (CP-conserving) is deduced directly from . In addition, we extract the slope parameters describing the energy dependence of the Dalitz plot. The whole set of our results fits well within the current phenomenological picture of the neutral-kaon system including CP violation and Chiral Perturbation Theory (ChPT). Received: 13 March 1998 / Published online: 3 September 1998