Recent results on rare kaon and pion decays are reviewed and prospects for future experiments are discussed.

The pion form factor at very large Q2 is obtained by using a new pion wave function. It shows that when Q2 >> (1.8GeV )2 the pion form factor reaches the asymptotic limit αs(Q) Q .

A weakly interacting massive particle (WIMP) is perhaps the most promising candidate for the dark matter in the Galactic halo. The WIMP detection rate in laboratory searches is fixed by the cross section for elastic WIMP-nucleus scattering. Here we calculate the contribution to this cross section from two-nucleon currents from pion exchange in the nucleus and show that it may, in some cases, be...

In hadronic Z decays, we compare Bose-Einstein correlations in π 0 pairs with those in identical charged pion pairs. We also measure Bose-Einstein correlations in triplets of identical charged pions. From the first study, the source radius is found to be smaller for π 0-π 0 than for π ±-π ± , as would be expected, e.g., in a string model. However, the second study shows that the data are consis...

For the first time single–spin asymmetries in semi–inclusive pion production are measured by the Hermes experiment with a transversely polarised hydrogen target. Two different sine–modulations are extracted which can be related to the transversity δq(x) and Sivers f 1T (x) quark distribution functions. The extracted sine–moments still contain small sub–leading twist contributions which can be e...

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Differences among calculations of the atmospheric neutrino beam can be traced in large part to differences in the representation of pion production by protons interacting with nuclei in the atmosphere. In this paper we review the existing data with the goal of determining the regions of phase space in which new measurements could help to improve the input to the calculations. preprint BA-99-73

Recent experiments by the HERMES group at HERA are measuring semiinclusive electroproduction of pions from deuterium. We point out that by comparing the production of π and π from an isoscalar target, it is possible, in principle, to measure charge symmetry violation in the valence quark distributions of the nucleons. It is also possible in the same experiments to obtain an independent measurem...

(June 29, 1999) We consider an “oriented” chiral condensate produced in the squeezed states of the effective field theory with timeand space-dependent pion mass parameter. We discuss the general properties of the solution, identifying condensate modes and determining the resulting pion distributions. The implementation of the dynamics in the form of sudden perturbation allows us to look for exa...

A model field theory, in which the interaction between quarks is mediated by dressed vector boson exchange, is used to analyse the pionic sector of QCD. It is shown that this model, which incorporates dynamical chiral symmetry breaking, asymptotic freedom and quark confinement, allows one to calculate fπ, mπ, rπ and the partial wave amplitudes in π-π scattering and obtain good agreement with th...