``Good-Walker'' + QCD dipoles = Hard Diffraction

The Good-Walker mechanism for diffraction is shown to provide a link between total and diffractive structure functions and to be relevant for QCD calculations at small x_{Bj}. For Deep-Inelastic scattering on a small-size target (cf. an onium) the r\^ ole of Good-Walker ``diffractive eigenstates'' is played by the QCD dipoles appearing in the $1/N_C$ limit of QCD. Hard diffraction is thus related to the QCD tripe-dipole vertex which has been recently identified (and calculated) as being a conformal invariant correlator and/or a closed-string amplitude. An extension to hard diffraction at HERA via $k_T-$factorisation of the proton vertices leads to interesting phenomenology.Comment: 6 pages latex + figure.eps; Invited talk at the DIS98 workshop, Brussels, April 199

High Energy Scattering from the AdS/CFTAdS/CFT Correspondence

We apply the AdS/CFT correspondence to derive expressions for the scattering amplitudes at high energy for gauge theories at strong coupling. A method is proposed based on the computation of correlators of Wilson loop operators by their stringy duals in AdS spaces using either the supergravity (weak field) or classical (minimal surface) approximations.Comment: 6 pages,1 figure,Invited talk at ``DIS 2000'', 25-30 April 2000, Liverpool, to appear in the Proceedings in a shortened versio

Unified approach to hard diffraction

Using a combination of S-Matrix and perturbative QCD properties in the small x_{Bj} regime, we propose a formulation of hard diffraction unifying the partonic (Ingelman-Schlein) Pomeron, Soft Colour Interaction and QCD dipole descriptions.Comment: 4 pages, 1 figure, to appear in Proceedings of 9th International Workshop on Deep Inelastic Scattering and QCD (DIS 2001), Bologna, Italy, 27 Apr-1 May 200

Soft Physics and Intermittency: Open Question(s) in Krakow

This contribution contains a summary of the Krakow meeting on Soft Physics and Fluctuations. It emphasizes both the experimental and the theoretical investigations on correlations/fluctuations and intermittency in multi-particle processes and discusses of the present status of this concept. A clarification of the main open questions in this field of research is now within reach, thanks to the studies presented at the meeting. Summary Talk of the Krakow Workshop on Multiparticle Physics, May, 4-7, 1993. E-mail contact: [email protected]: 12p., Plain Tex file, Saclay-T93/11

Testing resummed NLO-BFKL kernels

We propose a new method to test the (resummed) next-to-leading-order BFKL evolution kernels using the Mellin transformed j-moments of the proton structure function F_2.Comment: 12 pages,2 figures, To appear in the special issue of Acta Physica Polonica to celebrate the 65th Birthday of Professor Jan Kwiecinsk

Diffractive Production of the Higgs Boson

Diffractive production of the Higgs boson at hadron colliders is discussed in the light of the observed rate of hard diffractive dijet events at the Tevatron. The Higgs predictions of models successful for dijets are compared. LHC seems promising for a diffractive light Higgs boson and its mass determination. Hard diffractive dijets, diphotons and dileptons at the Tevatron (Run II) will be necessary to remove the remaining large uncertainties on cross-sections and signals.Comment: 4 pages,3 figures,1 table; Talk presented at the XXXVIIIth Rencontres de Moriond, QCD and High Energy Hadronic Interactions, Les Arcs, France, March 22-29 200

Factorial correlators: angular scaling within QCD jets

Factorial correlators measure the amount of dynamical correlation in multiplicity between two separated phase-space windows. We present the analytical derivation of factorial correlators for a QCD jet described at the double logarithmic (DL) accuracy. We obtain a new angular scaling property for properly normalized correlators between two solid-angle cells or two rings around the jet axis. Normalized QCD factorial correlators scale with the angular distance and are independent of the window size. Scaling violations are expected beyond DL approximation, in particular from the subjet structure. Experimental tests are feasible, and thus welcome.Comment: preprint SACLAY-T00-182, TSL/ISV-00-0239; 18 pages, latex, 4 figures; submitted to Eur. Phys. J.