Signatures of the neutral top-pion in eγe\gamma collisions

We calculate the contributions of the neutral top-pion $\pi_{t}^0$ to the process $e^-\gamma\to e^-\bar{t}c$ in the framework of topcolor-assisted technicolor(TC2) models and discuss the possible of detecting $\pi_t^0$ at the high energy linear $e^+e^-$ collider(LC). Our results show that $\pi_t^0$ can give significant contributions to this process. With reasonable values of the parameters in TC2 models, the cross section $\sigma$ can reach 0.19 fb which may be detected at the $e\gamma$ collisions based on the future LC experiments.Comment: latex files,11 pages, 3 figure

Pion-nucleus reactions in a microscopic transport model

We analyse pion-nucleus reactions in a microscopic transport model of the BUU type, which propagates nucleons, pions, deltas and N(1440)-resonances explicitly in space and time. In particular we examine pion absorption and inelastic scattering cross sections for pion kinetic energies T(pi) =85-315MeV and various target masses. In general, the mass-dependence of the experimental data is well described for energies up to the delta-resonance (\approx 160 MeV) while the absorption cross sections are somewhat overestimated for the higher energies. In addition we study the possible dynamical effects of delta- and pion-potentials in the medium on various observables as well as alternative models for the in-medium delta-width.Comment: 31 pages, UGI-93-0