Soft Colour Interactions and Diffractive Hard Scattering at the Tevatron

We make a brief presentation of the soft colour interactions models, the Soft Colour Interaction and the Generalised Area Law, and summarise the results when they are applied to p-pbar scattering. The models give a good description of the Tevatron data on production of W, bottom and jets in diffractive events, as well as jets with two rapidity gaps, alternatively leading particles. We also give predictions for diffractive J/psi production and discuss diffractive Higgs production at the Tevatron and LHC.Comment: 5 pages, 4 figures, uses JHEP style. Talk presented at the International Europhysics Conference on High Energy Physics (EPS HEP 2001), Budapest, 12-18 July 200

Traveling waves and the renormalization group improved Balitsky-Kovchegov equation

I study the incorporation of renormalization group (RG) improved BFKL kernels in the Balitsky-Kovchegov (BK) equation which describes parton saturation. The RG improvement takes into account important parts of the next-to-leading and higher order logarithmic corrections to the kernel. The traveling wave front method for analyzing the BK equation is generalized to deal with RG-resummed kernels, restricting to the interesting case of fixed QCD coupling. The results show that the higher order corrections suppress the rapid increase of the saturation scale with increasing rapidity. I also perform a "diffusive" differential equation approximation, which illustrates that some important qualitative properties of the kernel change when including RG corrections

The high energy asymptotics of scattering processes in QCD

High energy scattering in the QCD parton model was recently shown to be a reaction-diffusion process, and thus to lie in the universality class of the stochastic Fisher-Kolmogorov-Petrovsky-Piscounov equation. We recall that the latter appears naturally in the context of the parton model. We provide a thorough numerical analysis of the mean field approximation, given in QCD by the Balitsky-Kovchegov equation. In the framework of a simple stochastic toy model that captures the relevant features of QCD, we discuss and illustrate the universal properties of such stochastic models. We investigate in particular the validity of the mean field approximation and how it is broken by fluctuations. We find that the mean field approximation is a good approximation in the initial stages of the evolution in rapidity.Comment: 31 pages, 20 figures. The code for BK evolution can be downloaded from http://www.isv.uu.se/~enberg/BK/ v2: several points clarified, discussion of the solutions to the mean-field evolution enhanced through the study of a different class of initial conditions, references added; conclusions unchanged. To appear in Phys. Rev.

Hard Pomeron in exclusive meson production at ILC

We calculate the exclusive process gamma* gamma* ->rho rho at high energy. The Born order estimate and the leading (LLA) and next to leading order (NLLA) BFKL resummation effects show the feasibility of experimental detection in a quite large range of Q2 values at future high energy e+e- linear colliders.Comment: 4 pages, Presented at Photon2005, International Conference on the Structure and Interactions of the Photon, Warsaw 31.08-04.09.2005, by Samuel Wallo

LHC and Dark Matter Signals of Improved Naturalness

The Standard Model Higgs suffers from the hierarchy problem, typically implying new states within the reach of the LHC. If the Higgs is very heavy (~500 GeV) the states that cutoff the quadratic divergence may be beyond the reach of the LHC. However, in this case precision electroweak data require the Standard Model to be augmented with new states at the electroweak scale. We study a very simple model, with no new colored states, that allows a heavy Higgs whilst remaining consistent with experiments, and yielding the correct dark matter abundance. We investigate the possibilities for its discovery at the LHC and future dark matter detection experiments.Comment: 33 pages, 13 figures. Minor changes: version to appear in JHE

Testing the dynamics of high energy scattering using vector meson production

I review work on diffractive vector meson production in photon-proton collisions at high energy and large momentum transfer, accompanied by proton dissociation and a large rapidity gap. This process provides a test of the high energy scattering dynamics, but is also sensitive to the details of the treatment of the vector meson vertex. The emphasis is on the description of the process by a solution of the non-forward BFKL equation, i.e. the equation describing the evolution of scattering amplitudes in the high-energy limit of QCD. The formation of the vector meson and the non-perturbative modeling needed is also briefly discussed.Comment: 17 pages, 8 figures. Brief review to appear in Mod. Phys. Lett.

Vector Meson Photoproduction from the BFKL Equation II: Phenomenology

Diffractive vector meson photoproduction accompanied by proton dissociation is studied for large momentum transfer. The process is described by the non-forward BFKL equation which we use to compare to data collected at the HERA collider.Comment: 39 pages, 29 figure