Spin, branching ratios and production characteristics of the K*(1420)

An account is given of the reduction and analysis of data from bubble chambers. Initially, the principles of operation and the important advances in the bubble chamber technique are briefly described. Since the discovery of the bubble chamber principle, chamber volumes have increased in two decades by a factor of 106. The development in the chambers themselves has been accompanied by a parallel development in the techniques used to analyse the data. The development of film measuring machines is then outlined and the construction and performance of some of these machines are discussed. In the late 1950's manual machines such as Franckenstein were highly automated and they were operating on-line to computers by the second half of the 1960's with program assistance and error detection. Fully automatic machines, proposed in the early 1960's, did not live up to their early promise. Evidently automatic event recognition is a very sophisticated task and the crude methods at present available require far too much computer time. Problems with precision CRT's were resolved in the mid 1960's, and their advantages over mechanical scanning systems have been successfully exploited. At the present time semi-automatic CRT machines such as POLLY are proving most successful. Specialized processor hardware such as BRUSH and SATR may eventually offer the solution to complete automation. The rest of the article describes the geometrical reconstruction, kinematical fitting and statistical analysis of bubble chamber events. The problems of geometrical reconstruction in the present generation of chambers caused by the use of wide angle photography are discussed. A description of the common methods of presenting bubble chamber data and some of the mathematical techniques used in the analysis are also given.

http://iopscience.iop.org/article/10.1088/0034-4885/35/3/303/pdf

Data analysis techniques in high energy physics

Study of multi-body final states in K+p reactions at an incident momentum of 5 GeV/c

Density matrix elements and Donohue-Høgaasen parameters of resonances produced in π+p and γp reactions

Decays of interfering resonances and statistical tensors

Among the interactions of K+p at 5 GeV/c produced in the CERN 2 m and Saclay 81 cm hydrogen bubble chambers we have studied the four-body reactions K+p→ Kππ. The cross-sections for the various final states contributing to these reactions have been determined. A detailed analysis has been performed on the double-resonance production K+p→ K*(892)*(1236). Decay angular distributions for both resonances have been studied and single and joint spin-density matrix elements calculated as a function of four-momentum transfer. The results have been compared to the absorption-model predictions assuming pion exchange. Various quark-model predictions for the decay angular distributions have been tested. The quark-model relations derived on the basis of the additivity assumption only, are experimentally well satisfied. If additional conditions about the quark-quark scattering amplitudes are imposed, only some of the quark-model predictions agree with experiment.

W. Matt

Papers

Double-resonance production by 5 GeV/c K+ mesons on protons