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...

Doubly special relativity considers a deformation of the relativistic kinematics parametrized by high-energy scale, in such way that it preserves principle. When this is assumed to be applied any interaction between particles, one faces some inconsistencies. In order avoid them, we propose new perspective where affects only interactions elementary particles. A consequence proposal cannot modify...

To know the properties of a particle or a wave, one should measure how its energy changes with its momentum. The relation between them is called the dispersion relation, which encodes essential information of the kinetics. In a magnet, the wave motion of atomic spins serves as an elementary excitation, called a spin wave, and behaves like a fictitious particle. Although the dispersion relation ...

Human crowds often bear a striking resemblance to interacting particle systems, and this has prompted many researchers to describe pedestrian dynamics in terms of interaction forces and potential energies. The correct quantitative form of this interaction, however, has remained an open question. Here, we introduce a novel statistical-mechanical approach to directly measure the interaction energ...

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 ...