Summary Talk: First Workshop on Forward Physics and Luminosity Determination at the LHC

An attempt is made to summarize the discussion at the Workshop, except for the panel discussion on the ability of the LHC detectors to accommodate forward reactions. The Workshop focused on two main topics. The first topic was forward physics at the LHC. Predictions were made for forward reactions, including elastic scattering and soft diffractive processes, intopic was forward physics at the LHC. Predictions were made for forward reactions, including elastic scattering and soft diffractive processes, in terms of (multi) Pomeron exchange, using knowledge gained at lower energies. The survival probability of rapidity gaps accompanying hard subprocesses was studied. The nature of the Pomeron, before and after QCD, was exposed, and some aspects of small x physics at the LHC were considered. The second topic of the Workshop concerned the accuracy of the luminosity measuring processes at the LHC. Attention concentrated on three methods. The classic approach based on the optical theorem, secondly, the observation of the pure QED process of lepton-pair (l^+l^-) production by photon-photon fusion and, finally, the measurement of inclusive W and Z production.Comment: 21 pages,10 figures, LaTeX, Workshop at Helsinki, 31 October - 3 November, 200

Unintegrated generalised parton distributions

We show how the generalised (or skewed) parton distributions of the proton, H(x, xi; k_t^2, mu^2), unintegrated over the partonic transverse momenta, can be calculated from the known conventional parton distributions, q(x, mu^2) and g(x, mu^2), for small values of the skewedness parameter xi. We demonstrate the procedure by numerically evaluating the skewed unintegrated gluon. We also provide a simple approximate phenomenological form of the distribution, which may be used to make more rapid predictions of observables.Comment: 9 pages including 2 figure

Modeling missing transverse energy in V+jets at CERN LHC

I discuss a method to model the instrumental response of the CMS and ATLAS detectors at high transverse missing energies to dominant standard model V+jets backgrounds, where V is a Z, gamma or W, using multi-jet QCD events. The method is developed for new physics searches in early data at the Large Hadron Collider (LHC) with minimal recourse to simulation.Comment: Replaced with the published versio

F_2 at low Q^2

We analyse the data for the proton structure function $F_2$ over the entire $Q^2$ domain, including especially low $Q^2$, in terms of perturbative and non-perturbative QCD contributions. The small distance configurations are given by perturbative QCD, while the large distance contributions are given by the vector dominance model and, for the higher mass $q \overline{q}$ states, by the additive quark approach.Comment: Contribution to the "QCD98 Euroconference", (Montpellier, France, July 1998).4 pages, LaTeX, uses espcrc2.sty, 3 eps figures; error in the authors list correcte

Checking formalism for central exclusive production in the first LHC runs

We discuss how the early LHC data runs can provide crucial tests of the formalism used to predict the cross sections of central exclusive production.Comment: 7 pages, 6 figures; Based on a talk by A.D. Martin at the CERN - DESY Workshop "HERA and the LHC", 26 - 30 May 2008, CER

Competing many-body interactions in systems of trapped ions

We propose and theoretically analyse an experimental configuration in which lasers induce 3-spin interactions between trapped ions.By properly choosing the intensities and frequencies of the lasers, 3-spin couplings may be dominant or comparable to 2-spin terms and magnetic fields. In this way, trapped ions can be used to study exotic quantum phases which do not have a counterpart in nature. We study the conditions for the validity of the effective 3-spin Hamiltonian, and predict qualitatively the quantum phase diagram of the system.Comment: RevTex4 file, color figure