ar X iv : h ep - p h / 05 08 16 2 v 1 1 5 A ug 2 00 5 Electroproduction of two light vector mesons in the next - to - leading approximation

ar X iv : h ep - p h / 05 08 13 1 v 1 1 1 A ug 2 00 5 Einstein ’ s Contributions to Quantum Theory ∗

Einstein’s revolutionary light quantum hypothesis of 1905 and his further contributions to quantum theory are reviewed.

ar X iv : h ep - p h / 01 05 03 3 v 1 3 M ay 2 00 1 Threshold η and η ′ electroproduction off nucleons 1

The electroproduction of η and η ′ mesons on the proton and the neutron is investigated at tree level within the framework of U (3) chiral perturbation theory. In addition to the Born terms low-lying resonances such as the vector mesons and J P = 1/2 + , 1/2 − baryon resonances are included explicitly and their contributions are calculated. Results for the separated differential cross sections ...

ar X iv : h ep - p h / 05 08 14 2 v 1 1 1 A ug 2 00 5 Nature of the light scalar mesons

Despite the apparent simplicity of meson spectroscopy, light scalar mesons cannot be accommodated in the usual q ¯ q structure. We study the description of the scalar mesons below 2 GeV in terms of the mixing of a chiral nonet of tetraquarks with conventional q ¯ q states. A strong diquark-antidiquark component is found for several states. The consideration of a glueball as dictated by quenched...

ar X iv : h ep - p h / 03 08 31 8 v 1 2 9 A ug 2 00 3 On the structure of the scalar and D mesons

The qq spectrum is studied within a chiral constituent quark model. It provides with a good fit of the available experimental data from light (vector and pseudoscalar) to heavy mesons. The new D states measured at different factories are studied. The 0 ++ light mesons are analyzed as q ¯ q pairs or tetraquark structures.

ar X iv : h ep - p h / 06 08 21 3 v 1 1 8 A ug 2 00 6 Properties of D - Mesons from QCD Sum Rules with an improved spectral function