A Few Of The J / ¦· Decays Branching Ratio Measurements

This thesis consists of two parts. The first part is about the data processing in high-energy physics. First the brief introductions to basic concept of high-energy physics. Beijing electron-positron collider and data processing are given. The usages of some software are also shown. Then by using the large data sample of5.8x107 J/ψ events of Beijing Spectrometer (BES), the branching ratios forthree decay channels J/ψâ†'PP , J/ψâ†' PP Ï€0â†'PPrr ,J/ψâ†'PPp arestudied. The results for the first two channels agree with the values given in PDG book very well, because the background channels in these two cases are very low.For the third decay channel. PDG book only gave an upper limit, 3.1x10-4, which appears suppressed comparing with other large variety of three-body decay modes of the J/ψ , nearly all of which have branching ratios of order 10-3. Our analysis gave 3.84 x 10-4 This is particularly interesting in that the decay J/ψ- PP w is not suppressed relative to the other allowed three-body states.In the second part, the possible symmetry operations of the super-lattice in high dimensional space are explored. The C60 molecule and its ramifications.virus etc. have the symmetry of icosahedron. The main feature of the symmetry of icosahedron is the appearance of 5-fold axes. Because the crystal hasn't 5-fold axes in 3 dimensional space, many people cast their eyes to the high dimensional space. Using the properties of SO(n) group and the symmetry of crystal, I study the possible symmetry operations of the super-lattice in the high dimensional space. It is obtained that there are not only 5-fold axes, but also 8-, 10- and 12-fold axes in 4, 5 and 6 dimensional space.