Is Spin Physics Worthwhile?

Abstract

Spin Physics is here understood in a somewhat restricted sense. Even without polarized targets and polarized beams, the study of spin effects would be a very important part of particle physics in view of its close association with spectroscopy and with the implementation of selection rules. The advent of polarized targets and of polarized beams has however greatly enlarged the scope of scattering experiments and this is the only topic which is considered here under the general heading of spin physics. A large number of results, often embarrassing for otherwise successful models, and often provocative within the framework of too elementary theoretical ideas, bear witness to the importance of this research¹). Whilst the pertinent information is undoubtedly very valuable for particle physicists, it relies on very advanced and sophisticaled techniques in condensed matter physics and, more and more, in accelerator physics. Much ingenuity has to be developed and the efforts implied have to be fed by the significance of the physics results which are eventually to be obtained. A round table, bringing together experimentalists and theorists, but also target builders and machine builders, is the proper forum for a debate, whereby physics motivations and required effort can be discussed in some general perspective.