During the past fifty years, our concept of an elementary particle has undergone a fundamental change. Today we understand hadrons as bound states of quarks, and thus as composite. In strong interaction physics, quarks have become the smallest building blocks of nature. But the binding force between quarks confines them to their hadron, which cannot be split into its quark constituents. In term...

After a very brief review of twentieth century elementary particle physics, prospects for the next century are discussed. First and most important are technological limits of opportunities; next, the future experimental program, and finally the status of the theory, in particular its limitations as well as its opportunities. Invited talk given at the International Conference on Fundamental Scie...

The theory of elementary particles permitting to explain their constitution, sizes, bond energy, possible channels of decay, spectrum of weights and other properties is offered.

Gauge symmetries: These are local symmetries that act differently at each space-time point x = (t,x) . They create particularly stringent constraints on the structure of a theory. For example, gauge symmetry automatically determines the interaction between particles by introducing bosons that mediate the interaction. All current models of elementary particles incorporate gauge symmetry. (Detail...

WOLFGANG K. H. PANOFSKY Stanford Linear Accelerator Center Stanford University, Stanford, California 94309 ABSTRACT This paper reviews some key experiment,s of the past in which the same basic physical processes are attacked both through lepton-photon interactions and by using hadron machines as primary tools. Not surprisingly, it is conrludeh that the basic distinction between lepion-photon ph...

We derive compact analytical formulae of the Bonneau-Martin type for the reaction e + e − → ¯ f f γ with cuts on minimal energy and acollinearity of the fermions, where the photons may be emitted both from the initial or final states. Soft-photon exponentiation is also taken into account. One of the cleanest scattering processes at elementary particle accelerators is fermion-pair production in ...

We derive compact analytical formulae of the Bonneau-Martin type for the reaction e + e − → ¯ f f γ with cuts on minimal energy and acollinearity of the fermions, where the photons may be emitted both from the initial or final states. Soft-photon exponentiation is also taken into account. One of the cleanest scattering processes at elementary particle accelerators is fermion-pair production in ...

We consider the interaction of gravity, as expressed by Einstein’s Equations of General Relativity, to other force fields. We describe some recent results, discussing both the mathematics, and the physical interpretations. These results concern both elementary particles, as well as cosmological models. (This paper describes joint work variously done with with F. Finster, N. Kamran, B. Temple, a...

These proceedings summarize lectures that were delivered as part of the 2002 and 2003 Theoretical Advanced Study Institutes in elementary particle physics (TASI) at the University of Colorado at Boulder. They are intended to provide a pedagogical introduction to cosmology aimed at advanced graduate students in particle physics and string theory.

Symmetries and conservation laws have both played a vital part in the development of the Standard Model in the 20 century, and discoveries of symmetry violations have helped to propel elementary particle physics forward to the theory we have today. In this essay I attempt to introduce both the historical and theoretical background to this most important concept in particle physics, as well as g...