Diffractive Physics at HERA

A great interest for diffraction has been generated these last years by the HERA data. They give us the first opportunity to understand high energy diffractive physics in terms of a fundamental theory, i.e. QCD. A review of the main results from H1 and ZEUS in this field is presented and the relation with the proton structure function at small x-Bjorken values is discussed.Comment: 10 pages. Contribution to the Proceedings of Hadron Physics 200

Proposal for a Very Forward Proton Spectrometer in H1 after 2000

A new, very forward proton spectrometer (VFPS) with large acceptance is proposed to be installed in the proton beam of the H1 experiment after the luminosity upgrade in the year 2000. The spectrometer, located at 220 m downstream of the interaction point is based on the Roman Pot technique and consists of two stations situated in the cold section of the proton beam line. Physics motivations and a brief description of the proton spectrometer are presented.Comment: Contribution to the DIS-2000 proceeding

Deeply Virtual Compton Scattering at HERA

The Deeply Virtual Compton Scattering (DVCS) $\gamma^* p \to \gamma p$ cross section has been measured with the H1 detector at HERA with an increased precision and in an extended kinematic domain: at photon virtualities $4<Q^2<80$ GeV$^2$, and photon-proton c.m.s. energy $30<W<140$ GeV. The measurement is compared to NLO QCD calculations and to Colour Dipole model predictions.Comment: 4 pages, 4 figs, Proceedings of DIS0

Deeply Virtual Compton Scattering at H1 and ZEUS

Results on Deeply Virtual Compton Scattering at HERA measured by the H1 and ZEUS Collaborations are presented. The cross section, measured for the first time, is reported for $Q^2 > 2 GeV^2$, $30 < W < 120 GeV$ and $|t| < 1 GeV^2$.Comment: 4 pages, 3 figures, to appear in Proceedings of 9th International Workshop on Deep Inelastic Scattering and QCD (DIS 2001), Bologna, Italy, 27 Apr-1 May 200

Inclusive diffraction

Results are given on the measurements of the hard diffractive interactions at HERA $ep$ collider. The structure of the diffractive exchange in terms of partons and the factorisation properties are discussed, in particular by comparing the QCD predictions for dijets and $D^*$ with measurements both in the photo and electroproduction regimes.Comment: Contribution to the Proceedings of the Ringberg Workshop ``New Trends in HERA Physics 2005". 10 Page

MILOU : a Monte-Carlo for Deeply Virtual Compton Scattering

In this note, we present a new generator for Deeply Virtual Compton Scattering processes. This generator is based on formalism of Generalized Partons Distributions evolved at Next Leading Order (NLO). In the following we give a brief description of this formalism and we explain the main features of the generator for the elastic reactions, as well as for proton dissociation.Comment: 18 pages, 9 figure

QCD fits in diffractive DIS revisited

A new method of extracting diffractive parton distributions is presented which avoids the use of Regge theory ansatz and is in much closer relation with the factorization theorem for diffarctive hard processes.Comment: proceeding to PHOTON11 conferenc

Deeply Virtual Compton Scattering and Saturation Approach

We investigate the deeply virtual Compton scattering (DVCS) in the color dipole approach, implementing the dipole cross section through the saturation model, which interpolates successfully between soft and hard regimes. The imaginary and real part of the DVCS amplitude are obtained and the results are compared to the available data.Comment: 12 pages - Vers.2. Accepted by EJ