Diffraction studies at HERA are introduced, with reference to other communications to this Conference. Motivations and specific features of the experimental approaches are stressed.
A new experimental analysis of the diffractive process $ep rightarrow eXY$, where $Y$ denotes a proton or its low mass excitation with $M_Y<1.6$ GeV, has been performed with the H1 experiment at HERA cite{Aaron:2012ad}. The main results of this study are summarised in this document, together with the comparisons to other measurements and theoretical predictions.
A review is presented of diffractive vector meson production at HERA, with stress on the investigation of ``hard features and comparisons with theoretical predictions based on perturbative QCD approaches.
The exclusive diffractive production of vector mesons and real photons in ep collisions has been studied at HERA in a wide kinematic range. Here the most recent experimental results are presented together with a Regge-type model and projects for new diffractive studies at LHC.
In this article, recent measurements of diffraction in deep inelastic scattering are presented along with QCD fits to extract the partonic structure of the exchange. These so-called diffractive parton density functions can then be used in predictions for other processes to test factorisation in diffraction. This is an important verification of QCD and has significance for predicting exotic signals such as diffractive Higgs production at the LHC.