In this talk I review the recent progress made in the calculations of quarkonia production in fixed target experiments. NRQCD organizes the calculations in a systematic expansion in αs and v, the relative velocity between the heavy quarks. Within this formalism there are octet contributions which are not included in the color singlet model. These contributions depend upon unknown matrix element...

In this work, we attempt to study the Cabibbo-Kobayashi-Maskawa-favored [Formula: see text] ("S" denoting the scalar meson) decays within the perturbative QCD approach at the leading order and the leading power. Although the light scalar mesons are widely perceived as primarily the four-quark bound states, in practice it is hard for us to make quantitative predictions based on the four-quark pi...

In this talk I summarize a recently proposed mechanism to understand ππ scattering to 1 GeV. The model is motivated by the 1/NC expansion to QCD, and includes a current algebra contact term and resonant pole exchanges. Chiral symmetry plays an important role in restricting the form of the interactions. The existence of a broad low energy scalar (σ) is indicated.

The relevance of the axial current for pion production processes off the nucleon with real or virtual photons is revisited. Employing the hypothesis of a partially conserved axial current (PCAC), it is shown that, when all of the relevant contributions are taken into account, PCAC does not provide any additional constraint for threshold production processes that goes beyond the Goldberger-Treim...

We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The 12C(gamma,pi(0))(12)C*(4.4 MeV) reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a pi(0) spectrometer and to detect decay photons from the excited residual ...

The neutral pion electroproduction on the proton is considered in the framework phenomenological model based on the PCAC, current algebra with hard pions and chiral symmetry breaking interaction. The swave differential cross-section of the electroproduction of neutral pions off protons near the threshold is predicted as function photon momentum transfer squared k2 . The swave multipoles ReE0+ a...

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...