Production of Vector Mesons and Measurement of the Hadronic Component of Photon Light-Cone Wave Function at Hera

A detailed study of vector meson production (ϕ and J/ψ) in e^±p collisions at HERA with the ZEUS and H1 detector has been performed. The cross sections are measured as a function of Q², 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 → eπ⁺π^-p is also reported.