Summary of Working Group I: Hadron Structure

A summary is given on the main aspects which were discussed by the working group. They include new results on the deep inelastic scattering structure functions $F_2, xF_3, F_L$ and $F_2^{c\bar{c}}$ and their parametrizations, the measurement of the gluon density, recent theoretical work on the small $x$ behavior of structure functions, theoretical and experimental results on $\alpha_s$, the direct photon cross section, and a discussion of the event rates in the high $p_T$ range at Tevatron and the high $Q^2$ range at HERA, as well as possible interpretations.Comment: 22 pages latex, including 8 figures (ps,eps), to appear in the Proceedings of the International Conference on Deep Inelastic Scattering, Chicago, April 1997, AI

Threshold scans in Central Diffraction at the LHC

We propose a new set of measurements which can be performed at the LHC using roman pot detectors. The method exploits excitation curves in central diffractive pair production, and is illustrated using the examples of the W boson and top quark mass measurements. Further applications are mentioned.Comment: 11 page

Hard diffraction and the nature of the Pomeron

We ask the question whether the quark and gluon distributions in the Pomeron obtained from QCD fits to hard diffraction processes at HERA can be dynamically generated from a state made of ``valence-like'' gluons and sea quarks as input. By a method combining backward Q^2-evolution for data exploration and forward Q^2-evolution for a best fit determination, we find that the diffractive structure functions published by the H1 collaboration at HERA can be described by a simple ``valence-like'' input at an initial scale of order mu^2 ~ 2.3-2.7 GeV^2. The parton number sum rules at the initial scale mu^2 for the H1 fit gives 2.1\pm .1\pm .1 and .13\pm .01 \pm .02 for gluon and sea quarks respectively, corresponding to an initial Pomeron state made of (almost) only two gluons. It has flat gluon density leading to a plausible interpretation in terms of a gluonium state.Comment: 14 pages, 9 figure

Diffractive χ\chi Production at the Tevatron and the LHC

We present predictions for the diffractive production of $\chi$ mesons in the central rapidity region usually covered by collider detectors. The predicted cross sections are based on the Bialas-Landshoff formalism for both exclusive and inclusive production and makes use of the DPEMC Monte-Carlo simulation adapted with kinematics appropriate for small-mass diffractive production. We compare generator-level results with a CDF measurement for exclusive $\chi$ production, and study background and other scenarios including the contribution of inclusive $\chi$ production. The results agree with the Tevatron data and are extrapolated, highlighting the exclusive \chic production at LHC energies. A possible new measurement at the Tevatron using the D{\O}forward detectors is investigated, taking advantage of the dominance of exclusive production for high enough diffractive mass fraction.Comment: 9 pages, 2 figures, added akcnowledgment

Inclusive Higgs boson and dijet production via Double Pomeron exchange

We evaluate Higgs boson and dijet cross-sections at the Tevatron collider via Double Pomeron exchange when accompanying particles in the central region are taken into account. Such {\it inclusive} processes, normalized to the observed dijet rate observed at run I, noticeably increase the predictions for tagged (anti)protons in the run II with respect to {\it exclusive} ones, with the potentiality of Higgs boson detection.Comment: 6pages, 4 figure

Anomalous quartic WWgamma gamma, ZZgamma gamma, and trilinear WWgamma couplings in two-photon processes at high luminosity at the LHC

We study the W/Z pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and W/Z bosons for an integrated luminosity of 30 and 200 fb^{-1}. For simplicity and to obtain lower backgrounds, only the leptonic decays of the electroweak bosons are considered.Comment: 22 pages, 17 figures, sumitted to Phys. Rev.

A new determination of the Pomeron intercept in hard processes

A method allowing for a direct comparison of data with theoreticalpredictions is proposed for forward jet production at HERA. It avoids thereconstruction of multi-parton contributions by expressing the experimentalcuts directly as correction factors on the QCD forward jet cross-section. Anapplication to the determination of the {\it effective} Pomeron intercept inthe BFKL-LO parametrization from $d\sigma/dx$ data at HERA leads to a good fitwith a significantly higher {\it effective} intercept, $\alpha_P= 1.43 \pm0.025 (stat.) \pm 0.025 (syst.),$ than for proton (total and diffractive)structure functions. It is however less than the value of the pomeron interceptusing dijets with large rapidity intervals obtained at Tevatron. We alsoevaluate the rapidity veto contribution to the higher order BFKL corrections.The method can be extended to other theoretical inputs

Diffractive SUSY particle production at the LHC

We give detailed predictions for diffractive SUSY Higgs boson and top squark associated productions at the LHC via the exclusive double pomeron exchange mechanism. We study how the SUSY Higgs cross section and the signal over background ratio are enhanced as a function of tangent beta in different regimes. The prospects are particularly promising in the ``anti-decoupling'' regime, which we study in detail. We also give the prospects for a precise measurement of the top squark mass using the threshold scan of central diffractive associated top squark events at the LHC.Comment: 14 pages, 6 fig