Low x saturation at HERA ?

We compare the predictions of two distinct dipole models for inclusive and exclusive diffractive processes. While only one of these dipole models contains perturbative saturation dynamics, we show that the predictions of both models are fully consistent with the available HERA data, indicating no compelling evidence for saturation at present HERA energies.Comment: 8 pages, 4 figures, presented at the 26th Montreal-Rochester-Syracuse-Toronto (MRST) conference held at Concordia University, Montreal, Canada, 12th-14th May 2004. To appear in the proceeding

Photoproduction

Some selected topics in photoproduction are reviewed. In particular, the focus is on quasi-real photon-proton scattering as measured at HERA. Single & dijet rates and jet profiles are discussed, as are open charm production and inelastic charmonium production. The many intriguing theoretical issues which can be addressed through study of these processes are highlighted.Comment: 17 pages. Talk given at DIS97, Chicago, 14-18 April 199

Photon '97: Theory Summary

Some recent developments in the physics of photon induced reactions are discussed. My presentation is biased towards HERA physics with the other summary talk (of David Miller) being biased towards the gamma-gamma topics. Within the context of the data which were presented, I concentrate upon the the following topics: diffraction; jets; prompt photons; open charm and charmonium.Comment: 15 pages. To appear in the proceedings of the "Photon '97" conference, Egmond aan Zee, The Netherlands, May 199

Diffractive Higgs production: theory

We review the calculation for Higgs production via the exclusive reaction pp -> p+H+p. In the first part we review in some detail the calculation of the Durham group and emphasise the main areas of uncertainty. Afterwards, we comment upon other calculations.Comment: 19 pages. 11 figures. Contribution to the workshop "HERA and the LHC

Phenomenology of Distribution Amplitudes for the rho meson

We report on a successful extraction of the twist-2 and twist-3 Distribution Amplitudes (DAs) of the rho meson using the HERA data on diffractive rho photoproduction. We extract these DAs using several Colour Glass Condensate (CGC) inspired and a Regge inspired dipole models. All our extracted DAs are consistent with Sum Rules and lattice predictions.Comment: 4 pages, 2 figures, presented at the 19th International Workshop on Deep Inelastic Scattering and Related Subjects (DIS 2011), Jefferson Lab, Newport News, April 2011. To appear in the Proceeding

An AdS/QCD holographic wavefunction for the rho meson

We use an AdS/QCD holographic wavefunction to generate predictions for the rate of diffractive {\rho}-meson electroproduction that are in reasonable agreement with data collected at the HERA electron-proton collider.Comment: 4 pages, 3 figures, to appear in the Proceedings of 20th International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2012), Bonn, Germany, 26-30 March 201

THE STRUCTURE FUNCTION F_2^{\gamma}(x,Q^2) AT LEP2

The unique nature of the photon can be investigated in hitherto unexplored kinematic regions at LEP2. We discuss the theoretical significance of deep inelastic measurements and present a prescription that allows a theoretically and experimentally sensible separation of the so-called `anomalous' and `hadronic' components of the target photon. We perform preliminary studies regarding the ability to reconstruct the $\gamma^* \gamma$ CM energy (and hence $x$) and the usefulness of the easier to measure electron structure function.Comment: 6 pages Latex + 5 figures in a uuencoded fil

Colour Dipoles and Saturation

We employ values of the colour dipole cross section extracted from electroproduction and photoproduction data to show that gluon saturation effects are not required by the current HERA data but will become important in the THERA energy region.Comment: 3 pages, 2 figures. Talk given by G.S. at DIS 2000(Liverpool, April 2000