The Measurement of Tri-Linear Gauge Boson Couplings at e+e−e^+e^- Colliders

We describe a detailed study of the process $e^+e^- \to \ell\nu_\ell q \bar{q}$ and the measurement of tri-linear gauge boson couplings (TGV's) at LEP200 and at a 500~GeV and 1~TeV NLC. We included all tree level Feynman diagrams contributing to the four-fermion final states including gauge boson widths and non-resonance contributions. We employed a maximum likelihood analysis of a five dimensional differential cross section of angular distributions. This approach appears to offer an optimal strategy for measurement of TGV's. LEP200 will improve existing measurements of TGV's but not enough to see loop contributions of new physics. Measurements at the NLC will be roughly 2 orders of magnitude more precise which would probe the effects of new physics at the loop level.Comment: Latex file uses aipbook.sty with revtex and psfig.sty. 2 figures (uuencoded) will be added with figures command. Full postcript version with embedded figures is available at ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9504.ps To appear in the Proceedings of the International Symposium on Vector Boson Self-Interactions, UCLA, Feb. 1-3, 199

The Kolmogorov-Smirnov test and its use for the identification of fireball fragmentation

We propose an application of the Kolmogorov-Smirnov test for rapidity distributions of individual events in ultrarelativistic heavy ion collisions. The test is particularly suitable to recognise non-statistical differences between the events. Thus when applied to a narrow centrality class it could indicate differences between events which would not be expected if all events evolve according to the same scenario. In particular, as an example we assume here a possible fragmentation of the fireball into smaller pieces at the quark/hadron phase transition. Quantitative studies are performed with a Monte Carlo model capable of simulating such a distribution of hadrons. We conclude that the Kolmogorov-Smirnov test is a very powerful tool for the identification of the fragmentation process.Comment: 9 pages, 10 figure

Top-quark couplings to TeV resonances at future lepton colliders

We study the processes $W_L W_L \to t \bar t$ and $W_L Z_L \to t\bar b (\bar t b)$ at future lepton colliders as probes of the couplings of the top quark to resonances at the TeV scale. We consider the cases in which the dominant low energy feature of a strongly interacting electroweak symmetry breaking sector is either a scalar or a vector resonance with mass near 1 TeV. We find that future lepton colliders with high energy and high luminosity have great potential to sensitively probe these physics scenarios. In particular, at a 1.5 TeV linear collider with an integrated luminosity of 200 fb$^{-1}$, we expect about 120 events for either a scalar or a vector to decay to $t\bar t, t \bar b$. Their leading partial decay widths, which characterize the coupling strengths, can be statistically determined to about 10% level.Comment: 33 pages, 9 ps figures, 1 tabl

Study of Anomalous Couplings at a 500500~GeV e+e−e^+e^- Linear Collider with Polarized Beams

We consider the possibility of observing deviations from the Standard Model gauge-boson self-couplings at a future $500$~GeV $e^+ e^-$ linear collider. We concentrate on the case in which the electroweak symmetry breaking sector is strongly interacting and there are no new resonances within reach of the collider. We find a sensitivity to the anomalous couplings that is two orders of magnitude higher than that achievable at LEP II. We also show how a polarized electron beam extends the reach of the collider, allowing experiments to probe different directions in parameter space.Comment: 21 pages LaTeX, epsf figure

MSSM radiative contributions to the WWγ\gamma and WWZ form factors

We evaluate one-loop contributions to the C and P conserving $WW\gamma, WWZ$ form factors in the Minimal Supersymmetric Standard Model (MSSM), and in a more constrained Supergravity Grand Unified Theory (SUGRA-GUT). A systematic search of maximal effects in the available parameter space, shows that at LEP2 energy MSSM contributions can hardly reach the border of the most optimistic accuracy expected on those couplings, even for particles close to their production thresholds. At NLC energies, the effects are more comfortably of the order of the expected sensitivity, and may therefore provide useful information on MSSM parameter values which will not be available from direct particle production. We also discuss briefly some variance with other studies.Comment: Latex, 18 pages, 5 figures appended in a uuencoded fil

Effects of Non-Standard Tri-linear Couplings in Photon-Photon Collisions: I. γγ→W+W−\gamma \gamma \to W^+ W^-

The effect of anomalous couplings in $\gamma \gamma \to W^+ W^-$ is studied for different energies of the $\gamma \gamma$ mode of the next linear collider. The analysis based on the maximum likelihood method exploits the variables in the four-fermion semi-leptonic final state. Polarised differential cross sections based on the complete set of diagrams for these channels with the inclusion of anomalous couplings are used and compared to an approximation based on $\gamma \gamma \to W^+ W^-$ with full spin correlations. To critically compare these results with those obtained in $e^+ e^-$ we perform an analysis based on the complete calculation of the four-fermion semi-leptonic final state. The anomalous couplings that we consider are derived from the next-to-leading order operators in the non-linear realisation of symmetry breaking.Comment: paper in LATEX, 36 pages, 11 figures. Complete psfile also available via anonymous ftp at ftp://lapphp0.in2p3.fr/pub/preprints-theorie/enslapp636.uu or at http://lapphp0.in2p3.fr/preplapp/psth/enslapp636.ps.g