[en] Several aspects of tagging two-photon interactions at the LHC, as separation from Pomeron-Pomeron events or control of the tagging efficiency, are shortly discussed. (author)

[en] Recent measurements of the diffractive production of neutral vector mesons at HERA are reviewed. The issue of transition between 'soft' and 'hard' underlying production mechanism is discussed in context of the phenomenology of Regge theory and the predictions of the perturbative QCD. (author)

[en] In this thesis the luminosity measurement in the ZEUS experiment at HERA is described. After a general description of the HERA collider and the ZEUS experiment the luminosity measurement on the basis of the process ep→e'γp is described. Then the construction, performance, and calibration of the detectors for the luminosity monitor are described together with the data acquisition system. Thereafter the measuring procedure is considered together with the required corrections. Furthermore the background is considered together with its control methods. finally the different sources of errors are discussed. (HSI)

[en] A precise measurement of the spectrum of the photons from ep bremsstrahlung with the ZEUS luminosity monitor at HERA is reported. The measurement shows a reduced rate compared to the Bethe-Heitler spectrum for photon energies below 5 GeV. This suppression, called the beam-size effect, is explained by the finite transverse size of the beam overlap relative to the typical impact parameter in the process of ep bremsstrahlung at HERA energies. (orig.)

[en] A precise measurement of the spectrum of the photons from ep bremsstrahlung with the ZEUS luminosity monitor at HERA is reported. The measurement shows a reduced rate compared to the Bethe-Heitler spectrum for photon energies below 5 GeV. This suppression, called the beam-size effect, is explained by the finite transverse size of the beam overlap relative to the typical impact parameter in the process of ep bremsstrahlung at HERA energies. (orig.)

No abstract available

[en] A search for the process e+p → WX, with the subsequent decay W → eve , was performed using 66 pb-1 of e+p collision data taken with the ZEUS detector during the 1999-2000 running period. The process leads to final states characterized by isolated high transverse energy electrons and large missing transverse momentum PT

[en] FP420 is an R project to assess the feasibility of installing proton detectors at 420 m from the ATLAS and/or CMS interaction point(s) at the LHC, allowing the measurement, in high luminosity environment, of the spatial position and arrival time of protons scattered at very low angles with fractional momentum loss between 0.2 % and 2 %. This is expected to open a new program of electroweak, QCD and beyond-the-Standard-Model physics. The challenges of the project are presented, along with the solutions envisaged, notably for the detectors and the original moving mechanism to bring the detectors close to the beam, as recently reported in arXiv:0806.0302. The progress since then is discussed, in particular in the design and prototyping picosecond resolution time-of-flight detectors capable of accurate vertex reconstruction for background rejection at high-luminosities as well as in the in-situ calibration techniques. GasToF - a Cerenkov detector filled with dense gas and readout by fast MCP-PMTs is proposed for very precise ToF measurements of forward-scattered protons at the LHC. The test beam results, cosmic ray measurements and detailed simulations are presented showing that the GasToF detectors reach the time resolution of several ps and high efficiency very close to its mechanical edge. Operation of GasToF in high luminosity conditions depends on the performance of MCP-PMTs at large event rates. Several studies were performed using a dedicated fast laser setup for testing two kinds of MCP-PMTs - the Hamamatsu R3809U-50 and the Photek 210, and the obtained results are reported. (author)

[en] Experimental prospects for studying high-energy photon interactions at the LHC are discussed. Role of the forward proton detectors in selection and reconstruction of such events is briefly described. Physics cases for the two-photon fusion and photon-proton interactions are introduced. Several examples, as the associated WH photo-production, or two-photon production of supersymmetric pairs are given. Finally, a possibility of studying the photon interactions in ion collisions is shortly discussed

[en] The exclusive two-photon production at the LHC of pairs of W and Z bosons provides a novel and unique test-ground for the electroweak gauge boson sector. In particular it offers, thanks to high gamma-gamma center-of-mass energies, large and direct sensitivity to the anomalous quartic gauge couplings otherwise very difficult to investigate at the LHC. An initial analysis has been performed assuming leptonic decays and generic acceptance cuts. Simulation of a simple counting experiment has shown for the integrated luminosity of 10 fb^-1 at least four thousand times larger sensitivity to the genuine quartic couplings, a₀^W, a₀^Z, a_C^W and a_C^Z, than those obtained at LEP. The impact of the unitarity constraints on the estimated limits has been studied using the dipole form-factors. Finally, differential distributions of the decay leptons have been provided to illustrate the potential for further improvements of the sensitivities. (authors)