International Journal of Modern Physics A

The current status of measurements of the nucleon structure functions and their understanding is reviewed. The fixed target experiments E665, CCFR and NMC and the HERA experiments H1 and ZEUS are discussed in some detail. The extraction of parton momentum distribution functions from global fits is described, with particular attention paid to much improved information on the gluon momentum distribution. The status of α_s measurements from deep inelastic data is reviewed. Models and nonperturbative approaches for the parton input distributions are outlined. The impact on the phenomenology of QCD of the data at very low values of the Bjorken x variable is discussed in detail. Recent advances in the understanding of the transition from deep inelastic scattering to photoproduction are summarized. Some brief comments are made on the recent HERA measurements of the ep NC and CC cross-sections at very high Q².

Quantum field theory provides a consistent framework to deal with unstable particles. We present here an approach based on field theory to describe the production and decay of unstable and mixed systems. The formalism is applied to compute the time evolution amplitudes of K⁰ and studied in DAPHNE and CPLEAR experiments. We also introduce a new set of parameters that describe CP violation in K→ππ decays without recourse to isospin decomposition of the decay amplitudes.