Production of vector mesons and measurement of the hadronic component of photon light-cone wave function at HERA

Abstract

A detailed study of vector meson production ($\phi$ and $J/\psi$) in $e^\pm p$ collisions at HERA with the ZEUS and H1 detector has been performed. The cross sections are measured as a function of $Q^2$, $W$ and $t$. In this contribution, the results are summarised, compared to theoretical calculations and the dynamical picture emerging in perturbative QCD is highlighted. The measurement of the hadronic component of the photon light-cone wave function in the exclusive production of di-pions, $ep\to e \pi^+\pi^- p$ is also reported.Comment: 4 pages, 6 figures, Submitted to be published in the Proceedings of to 32nd International Conference on High-Energy Physics (ICHEP 04), Beijing, China, 16-22 Aug 200