The subject of this year's conference, as of the six previous meetings, was again elementary particle physics. One of the main topics of current interest here is the understanding of strong interactions; some of the attempts to explain them are discuBBed at length in these proceedings, including current algebra, Regge pole theory and effective Lagrangians. On the other hand, the proceBses of weak interactions, too, are not yet fully understood, especially when strong interactions intervene, as in the radiative corrections to weak decays. Several other aspects of elementary particle physics are also treated in this volume, every one of them another step towards a thorough understanding of the sub. atomic world. I want to take this opportunity to thank all the members of my staff for their assistance in organizing the meeting and for their help in preparing the manuscripts. Graz, June 1968 P. Urban Contents Urban, P. Introduction ................................................. V Nilsson, J. Discrete Symmetries in Elementary Particle Physics ............ 1 Pietschmann, H. Semi-Leptonic Weak Decay Processes ....•............... 88 Dothan, Y. Introduction to Recent Developments in Regge Pole Theory .... 126 Koller, K. On Feynman Diagrams wi~h Infinite Dimensional Representations of the Lorentz Group 0 (3,1) ......................................... 161 Giirsey, F. Effective Lagrangians in Particle Physics. . . . . . . . . . . . . . . .. . . 185 . . . .
