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Neutral Higgs-boson-pair production provides the possibility of studying the trilinear Higgs couplings at future high-energy colliders. We present the QCD corrections to the gluon-initiated processes in the limit of a heavy top quark in the loops and the Drell-Yan-like pair production of scalar and pseudoscalar Higgs particles. The pp cross sections are discussed for CERN LHC energies within the standard model and its minimal supersymmetric extension. The QCD corrections are large, enhancing the total cross sections significantly.

XV goals. We then discuss the baseline experimental facilities. Our baseline design is an accelerator of 500 GeV center-of-mass energy, with polarized e-beams, and with two interaction regions that share the luminosity. The design envisions a number of upgrade paths. These include low-energy precision measurements in one of the two regions and e+e-collisions at multi-TeV energies in the other. The logic of these plans is described in some detail. In the subsequent chapters, we discuss the possible options of positron polarization, operation of a yy collider by laser backscattering from electron beams, and operation for e-e-collisions. In each case, we review the promise and the technological problems of the approach.

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Elementary cross sections for the production of supersymmetric partners of the known constituents and gauge bosons in collisions of quarks and gluons are calculated in tree approximation. Standard renormalization-group-improved parton-model methods are then used to estimate differential and integrated production cross sections in proton-proton and proton-antiproton collisions. For completeness, some analogous results are presented for electron-positron collisions. Decay modes, experimental signatures, and bounds on masses of supersymmetric partners are surveyed, and prospects for future searches are discussed.

Physics at the Large Hadron Collider (LHC) and the International e + e − Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC / LC Study Group so far is summarised in this report. Possible topics for future studies are outlined.4