Soft hadron production in pp interactions up to ISR energies

Soft hadron production is described as a two-step process, where the interaction of the partonic constituents of the colliding hadrons leads to the production of intermediate subsystems (fireballs), which decay subsequently into hadrons. The weights of the various final states are derived from the corresponding phase-space factors modified by empirical transition elements. The results compare well with data at energies between particle production thresholds and ISR energies. Special emphasis is put on correlation data, which offer the opportunity to shed some light on the question whether particle production proceeds via fireballs or strings.Comment: 14 pages, 19 figure

Research Summary on Fracture of Swollen Rubber

Crack propagation and critical strain in swollen rubbe

Cluster expansion for dimerized spin systems

We have studied dimerized spin systems by realizing the cluster expansion to high order. We have extended our previous dimer expansion for one-dimensional systems to cover weakly interacting chains for a quantitative description of three dimensional materials like PHCC and KCuCl_3. By comparison with recent inelastic neutron scattering data we are able to determine the exchange energies between individual spins. We have further investigated the incommensurate region of zigzag chains with isotropic exchange coupling constants near the disorder-line where the dispersion curve exhibits a minimum at a finite wavevector. Our approach clearly shows the gradual transition between the minimum of the dispersion at wavevector 0 and wavevector Pi within this region. The extent of the incommensurate regime is given analytically in an expansion in the coupling constants.Comment: 3 pages, 3 figures; contribution to ICNS2001; uses svjour.clo, svglobal.clo (included