Showing papers by "Richard Phillips Feynman published in 1971"

Current Matrix Elements from a Relativistic Quark Model

Abstract: A relativistic equation to represent the symmetric quark model of hadrons with harmonic interaction is used to define and calculate matrix elements of vector and axial-vector currents. Elements between states with large mass differences are too big compared to experiment, so a factor whose functional form involves one arbitrary constant is introduced to compensate this. The vector elements are compared with experiments on photoelectric meson production, Kl3 decay, and ω→πγ. Pseudoscalar-meson decay widths of hadrons are calculated supposing the amplitude is proportional (with one new scale constant) to the divergence of the axial-vector current matrix elements. Starting only from these two constants, the slope of the Regge trajectories, and the masses of the particles, 75 matrix elements are calculated, of which more than 3/4 agree with the experimental values within 40%. The problems of extending this calculational scheme to a viable physical theory are discussed.

Phenomenology in particle physics, 1971

Abstract: What is phenomenology? Reach not for your dictionary; make no vain efforts to pronounce it; we will come clean and explain all. Science is noted for a competitive and helpful interaction between theorists and experimentalists. Unfortunately in almost all developing sciences, the moving hand of time drives a widening wedge between theory and experiment. Thus theorists are fully occupied in the mathematical and philosophical intricacies of their latest ideas. Again, experimentalists must concentrate on the design of their apparatus to insure they will get the best possible results current technology will allow. Phenomenology seeks to close the gap between those once close friends, theory and experiment, and so restore the interaction which is both vital to and characteristic of science. Although a classical concept, phenomenology is best known in its second-quantized form. The basic tool of the phenomenologist is, first, the construction of simple models that embody important theoretical ideas, and then, the critical comparison of these models with all relevant experimental data. It follows that a phenomenologist must combine a broad understanding of theory with a complete knowledge of current and future feasible experiments in order to allow him to interact meaningfully with both major branches of a science. The impact of phenomenology is felt in both theory and experiment. Thus it can pinpoint unexpected experimental observations and so delineate areas where new theoretical ideas are needed. Further, it can suggest the most useful experiments to be done to test the latest theories. This is especially important in these barren days where funds are limited, experiments take many "physicist-years" to complete, and theories are multitudinous and complicated. Phenomenology is applicable in many sciences but this conference was organized with the hope of emphasizing the wide scope and importance of phenomenology in particle physics. In fact, in the time available, not even all the important applications to particle physics could be covered. Some of these omissions were repaired in a workshop, held at Caltech just after the main conference reported here, and devoted to physics at intermediate energies (~< 5 GeV). This area is particularly suitable for phenomenology as the qualitative features have been well explored and further progress demands difficult experiments with high statistics. Phenomenology can indicate, for instance, which of the some hundred (quasi) two body reactions will be most fruitful to study. In the following we map some of the more active fields of phenomenology indicating where they have been covered in either the present volume, our companion workshop, or elsewhere. The contents of the current volume are summarized in more detail in the abstracts of the invited papers which have been collected together in pages xi to xvi. We are indebted to many people for making this conference possible: Professor R.B. Leighton for his generous sponsorship; Nancy Hopkins and James Black of the Caltech Alumni Office for their efficient and cheerful organization; the session chairmen, M. Gell-Mann, W. Selove, J.D. Bjorken, M.J. Moravcsik, J.D. Jackson, T. Ferbel, R.L. Walker and S.C. Frautschi, for the smooth running of the conference; Susan Berger for her delightful cover; and our secretaries for their careful typing, with an especial thank you to Chris St.Clair who also drew the amusing illustrations. Alvin Tollestrup originally had the good idea of holding a phenomenology conference: We are grateful to him and our colleagues at Caltech for the encouragement which has made the organization and editing of this conference so enjoyable.