Frank Cuypers

Top quarks and CP violation in polarized e+e− collisions

Abstract Electroweak dipole moments of the top quark are conjectured and their effect in polarized e + e − collisions is examined for the expectation values of two different CP -odd observables. Oneof these observables probes the real part of the dipole moments whereas the other probes their imaginary part. It turns out that varying the polarization of the electron beam substantially enhances the resolving power of the experiment.

Standard model predictions for the reaction e−e−→W−W−νeνe

Abstract We study the process e − e − → W − W − ν e ν e within the framework of the standard model of electroweak interactions. This mechanism for producing two W − bosons is a potential background for exotic reactions violating lepton number conservation. At a centre-of-mass energy of 500 GeV the total cross section is calculated to be 2.28 fb for unpolarized beams. The energy behaviour of the cross section as well as some instructive differential distributions are shown and the topology of the final state is discussed.

Testing anomalous W couplings in e−e− collisions

Abstract We analyze the influence of anomalous gauge couplings in the reaction e−e− → e−W−νe at a 500 GeV linear collider. The limits imposed by this process on deviations from the standard model of electro-weak interaction, are competitive with those inferred from other high energy experiments. Furthermore, the allowed domain in the parameter space is quite different, and hence such an experiment would more than complement the other direct searches.

Electron-electron scattering as a probe of anomalous gauge couplings

Abstract The effect of anomalous gauge couplings on polarized e − e − scattering cross sections is examined. It turns out that different combinations of beam polarizations provide constraints which are complementary to each other and to those obtained from other experiments, such as e + e − , e − γ and γγ collisions.

LEPTOQUARK PRODUCTION IN e−e− SCATTERING

We consider the production of scalar and vector leptoquarks in e−e− collisions. Although this reaction is not competitive with, e.g., e−γ scattering for discovering these heavy states, it is the main process susceptible of differentiating two important classes of leptoquarks.

Probing anomalous quartic vector boson couplings in e−e− collisions

Abstract We study the incidence of genuine vector boson couplings in the reactions e − e − → e − e − Z 0 Z 0 , e − ν e Z 0 W − and ν e ν e W − W − . We find that a linear collider operated in the e − e − mode will provide bounds on these couplings which are competitive with those to be obtained in the e + e − mode.

Production of heavy selectrons in e - γ collisions

We study the production and decay of heavy selectrons in the electron-photon mode of a linear collider of the next generation. The standard model backgrounds can be substantially reduced by appropriate kinematical cuts. As a consequence, selectrons far heavier than the kinematical threshold for pair production are shown to be easily discoverable for large portions of the supersymmetry parameter space. We also describe a model-independent kinematical measurement of the mass of the lightest neutralino.

Model-independent Z' limits from electron-electron collisions

Abstract Model independent constraints on the mass of an extra neutral gauge boson and its couplings to charged leptons are given for the e − e − option of a future linear collider. Analytic exclusion limits are derived in the Born approximation. The results are compared with those of the e + e − mode. The influence of radiative corrections is discussed.

Leptoquark production in e−γ scattering

Abstract We perform a model-independent analysis of the production of scalar and vector leptoquarks in the e−γ mode of a linear collider of the next generation. Since these leptoquarks are produced singly, higher masses can be probed than in other collider modes, like e+e− scattering. We discuss the discovery potential and show how polarization and angular distributions can be used to distinguish between the different types of leptoquarks.

Physics with like‐sign muon beams in a TeV muon collider

We point out that both the specific lepton number content and the high energies potentially attainable with muon‐muon colliders make it advisable to consider the technical feasibility of including an option of like‐sign incoming beams in the studies towards a proposal to build a muon‐muon collider with center‐of‐mass energies in the TeV region. This capability will add some unique physics capabilities to the project. Special attention will have to be paid to polarization retention for the muons.