Study of Single W production in e-gamma collisions through the decay lepton spectrum to probe gamma-WW couplings

We investigate the effect of anomalous gamma-W-W couplings in e-gamma --> nu W through the angular and energy spectrum of the secondary leptons. Within the narrow-width approximation, a semi-analytical study of the secondary lepton energy-angle double distribution is considered. Utility of observables derived from this is demonstrated by considering the anomalous coupling, delta-kappa-gamma. Results of our investigation for typical ILC machine considered at Ecm = 300-1000 GeV re-affirms potential of this collider as a precision machine.Comment: Typos corrected, discussion added in section 2 for clarity, error in fig.2 corrected, figures 7 and 8 replaced with better resolutio

Lepton Number Violating Radiative WW Decay in Models with R-parity Violation

Models with explicit R-parity violation can induce new rare radiative decay modes of the $W$ boson into single supersymmetric particles which also violate lepton number. We examine the rate and signature for one such decay, $W\rightarrow \tilde l\gamma$, and find that such a mode will be very difficult to observe, due its small branching fraction, even if the lepton number violating coupling in the superpotential is comparable in strength to electromagnetism. This parallels a similar result obtained earlier by Hewett in the case of radiative $Z$ decays.Comment: 10 pages, 2 figures(available on request), LaTex, ANL-HEP-PR-92-8

Hadronic WW production and the Gottfried Sum Rule

The difference in production rate between $W^+$ and $W^-$ at hadron colliders is very sensitive to the the difference between up- and down-quark distributions in the proton. This sensitivity allows for a variety of useful measurements. We consider the difference $d_s(x,Q^2) - u_s(x,Q^2)$ in the sea distributions and the difference $\Delta u(x,Q^2) - \Delta d(x,Q^2)$ in the polarized parton distribution functions. In both cases we construct an asymmetry to reduce systematic uncertainties. Although we discuss measurements at the Tevatron and future hadron colliders, we find that the Brookhaven Relativistic Heavy Ion Collider (RHIC) is the most appropriate hadron collider for these measurements.Comment: 19 pages (20 figures available from the authors), MAD/PH/74

Flavor Asymmetry of the Nucleon Sea and W Boson Production

The advantage and feasibility of using $W$-boson production to extract unique information on the flavor asymmetry of the $\bar u$ and $\bar d$ sea-quark distributions in the proton are examined. The $W^+$ and $W^-$ production cross section ratios in $p+p$ collisions are shown to be sensitive to the $\bar d/ \bar u$ ratios, and they are free from charge-symmetry-breaking and nuclear-binding effects. The feasibility for measuring these ratios at the RHIC and LHC proton-proton colliders, as well as the expected sensitivity to the $\bar d/ \bar u$ ratios, are also presented.Comment: 7 pages, 4 figures (updated figures

Flavor Asymmetry of Antiquark Distributions in the Nucleon

1. Introduction 2. Possible violation of the Gottfried sum rule 2.1 Gottfried sum rule 2.2 Early experimental results 2.3 NMC finding and recent progress 2.4 Small $x$ contribution 2.5 Nuclear correction: shadowing in the deuteron 2.6 Parametrization of antiquark distributions 3 Expectations in perturbative QCD 3.1 Operator product expansion 3.2 Perturbative correction to the Gottfried sum 4 Theoretical ideas for the sum-rule violation 4.1 Lattice QCD 4.2 Pauli exclusion principle 4.3 Mesonic models 4.3.1 Meson-cloud contribution 4.3.2 Chiral models 4.3.3 Anomalous $Q^2$ evolution 4.4 Diquark model 4.5 Isospin symmetry violation 4.6 Flavor asymmetry ubar-dbar in nuclei 4.7 Relation to nucleon spin 4.8 Comment on effects of quark mass and transverse motion 5 Finding the flavor asymmetry ubar-dbar in various processes 5.1 Drell-Yan process 5.1.1 Fermilab-E866 results 5.2 W and Z production 5.3 Quarkonium production at large $x_{_F}$ 5.4 Charged hadron production 5.5 Neutrino scattering 5.6 Experiments to find isospin symmetry violation 6 Related topics on antiquark distributions 7 Summary and outlookComment: 3+79 pages, LATEX2e, 29 eps figures. Physics Reports in press. Complete postscript file is available at http://www.cc.saga-u.ac.jp/saga-u/riko/physics/quantum1/structure.html Email: [email protected]

Physics Opportunities of e+e- Linear Colliders

We describe the anticipated experimental program of an e+e- linear collider in the energy range 500 GeV -- 1.5 TeV. We begin with a description of current collider designs and the expected experimental environment. We then discuss precision studies of the W boson and top quark. Finally, we review the range of models proposed to explain the physics of electroweak symmetry breaking and show, for each case, the central role that the linear collider experiments will play in elucidating this physics. (to appear in Annual Reviews of Nuclear and Particle Science)Comment: 93 pages, latex + 23 figures; typos corrections + 1 reference adde

CP-violating dipole form factors of the top quark and tau lepton in scalar leptoquark models

We calculate the CP-violating electric and weak dipole form factors of the top quark and the tau lepton in models with scalar leptoquarks coupling only to the third generation of quarks and leptons. We obtain numerical values of the real and imaginary parts of these form factors at various energies for different values of leptoquark masses and couplings. The existing limits on the tau electric and weak dipole form factors allows us to put a limit on the masses and couplings of such leptoquarks and therefore on the top electric and weak dipole form factors. We also discuss constraints on the form factors coming from indirect limits on leptoquark masses and couplings deduced from LEP results on Z properties.Comment: 22 pages, LaTeX, includes 14 figures in postscript file

Atom Optics Quantum Pendulum

We explain the dynamics of cold atoms, initially trapped and cooled in a magneto-optic trap, in a monochromatic stationary standing electromagnetic wave field. In the large detuning limit the system is modeled as a nonlinear quantum pendulum. We show that wave packet evolution of the quantum particle probes parametric regimes in the quantum pendulum which support classical period, quantum mechanical revival and super revival phenomena. Interestingly, complete reconstruction in particular parametric regime at quantum revival times is independent of potential height.Comment: 14 pages, 7 figure