5 research outputs found
Probing the Top-Quark Electric Dipole Moment at a Photon Linear Collider
We probe the top-quark electric dipole moment (EDM) in top-quark pair
production via photon-photon fusion at a photon linear collider. We show how
linearly-polarized photon beams can be used to extract information on the
top-quark EDM without the use of complicated angular correlations of top-quark
decay products. If the luminosity of the laser back-scattered photon-photon
collisions is comparable to that of the collisions, then the
measurement of the top-quark EDM obtained by counting top-quark-production
events in photon fusion can be as accurate as the measurement obtained by
studying the decay correlations in collisions using a
perfect detector.Comment: Latex, 11 pages, 1 figure (not included). One compressed postscript
file of the paper available at
ftp://ftp.kek.jp/kek/preprints/TH/TH-443/kekth443.ps.g
Probing the CP nature of the Higgs bosons by top-pair production at photon linear colliders
We study effects of heavy Higgs bosons on the top-pair production process at
photon linear colliders. The interference patterns between the resonant
Higgs-production amplitudes and the continuum QED amplitudes are examined. The
patterns tell us not only the CP nature of the Higgs bosons but also the phase
of the --Higgs vertex which gives new information about the Higgs
couplings to new charged particles. We point out that it is necessary to use
circularly polarized photon beams to produce efficiently heavy Higgs bosons
whose masses exceed the electron beam energy, and show that the above
interference patterns of the production amplitudes can be studied by observing
top decay angular distributions. Analytic expressions for the helicity
amplitudes for the sequential process are presented in
terms of the generic production amplitudes.Comment: 34 pages, LATEX file with 6 PS figures, comments adde
How to trap a non-standard penguin? Isospin Symmetry Violations in B-decays with Enhanced Chromomagnetic Dipole Operator
A recently proposed Non-Standard Model solution to the problem of low
semileptonic branching ratio B_{SL} which suggests a large branching ratio for
the decay is critically examined. It is shown that the effects of
the Enhanced Chromomagnetic Dipole Operator might lead to significant
violations of isospin symmetry in rare radiative decays of B-mesons.Comment: 8 pages, RevTex, 2 figure
Tracing CP violation in the production of top quark pairs by multiple TeV proton-proton collisions
We investigate the possibilities of searching for non-standard CP violation
in at multiple TeV collision energies. A general kinematic
analysis of the underlying partonic production processes and
in terms of their density matrices is given. We evaluate
the CP-violating parts of these matrices in two-Higgs doublet extensions of the
standard model (SM) and give results for CP asymmetries at the parton level. We
show that these asymmetries can be traced by measuring suitable observables
constructed from energies and momenta of the decay products of and . We find CP-violating effects to be of the order of and show that
possible contaminations induced by SM interactions are savely below the
expected signals.Comment: 24 pages, SLAC-PUB-6403, PITHA 93/43, 9 Figs. available upon request.
Written in LaTe