I discuss recent results of inclusive and exclusive electroproduction experiments at Jefferson Lab. They include measurements of the spin response for protons and neutrons in the resonance region, exclusive single pion and multiple pion production to measure resonance transition multipoles, and searches for missing quark model states. A brief outlook to the new domain of Generalized Parton Dist...

We propose an intensity-dependent pion-nucleon coupling Hamiltonian within a unitary multiparticle-production model of the Auerbach-Avin-Blankenbecler-Sugar (AABS) type in which the pion field is represented by the thermal-density matrix. Using this Hamiltonian, we explain the appearance of the negative-binomial (NB) distribution for pions and the well-known empirical relation, the so-called Wr...

Recent developments and open issues in chiral dynamics with strange quarks are reviewed. Topics include: Order parameters of chiral symmetry breaking, the flavor dependence of these order parameters, speculations about the phase structure of QCD with varying number of flavors, OZI violation and its natural emergence in case of a small strange quark condensate, heavy kaon chiral perturbation the...

We calculate the cross section of a pion diffraction dissociation in two jets with large transverse momenta originating from a hard gluon exchange between the pion constituents. To the leading logarithmic accuracy (in energy), the contribution coming from small transverse separations between the quark and the antiquark in the pion acquires the expected factorized form, the longitudinal momentum...

Measurements of elementary pp collisions are essential for understanding heavy ion collisions. Results for pp collisions at 200 and 62.4 GeV are presented. At both energies NLO pQCD describes pion production well. The measured pion transverse single spin asymmetries are very large at 62.4 GeV and are reasonably well described by models relying on pQCD at transverse momenta larger than 1 GeV/c.

I discuss recent results of inclusive and exclusive electroproduction experiments at Jefferson Lab. They include measurements of the spin response for protons and neutrons in the resonance region, exclusive single pion and multiple pion production to measure resonance transition multipoles, and searches for missing quark model states. A brief outlook to the new domain of Generalized Parton Dist...

A brief overview on recent model calculations for near threshold pion production in nucleon-nucleon collisions is given. Results from our own investigations of the reactions pp → ppπ 0 and pn → dπ 0 are presented. Direct production, heavy meson exchange and pion rescattering are taken into account. For the latter a T-matrix obtained from a microscopic model of the πN interaction is employed. We...