21,570 research outputs found
Determining at Electron-Positron Colliders
Verifying is critical to test the three generation
assumption of the Standard Model. So far our best knowledge of is
inferred either from the unitarity of CKM matrix or from single
top-quark productions upon the assumption of universal weak couplings. The
unitarity could be relaxed in new physics models with extra heavy quarks and
the universality of weak couplings could also be broken if the coupling
is modified in new physics models. In this work we propose to measure
in the process of without prior knowledge of the number
of fermion generations or the strength of the coupling. Using an
effective Lagrangian approach, we perform a model-independent analysis of the
interactions among electroweak gauge bosons and the third generation quarks,
i.e. the , and couplings. The electroweak symmetry
of the Standard Model specifies a pattern of deviations of the --
and -- couplings after one imposes the known experimental
constraint on the -- coupling. We demonstrate that, making use of
the predicted pattern and the accurate measurements of top-quark mass and width
from the energy threshold scan experiments, one can determine from the
cross section and the forward-backward asymmetry of top-quark pair production
at an {\it unpolarized} electron-positron collider.Comment: publish versio
Constraints on cosmological models from lens redshift data
Strong lensing has developed into an important astrophysical tool for probing
both cosmology and galaxies (their structures, formations, and evolutions). Now
several hundreds of strong lens systems produced by massive galaxies have been
discovered, which may form well-defined samples useful for statistical
analyses. To collect a relatively complete lens redshift data from various
large systematic surveys of gravitationally lensed quasars and check the
possibility to use it as a future complementarity to other cosmological probes.
We use the distribution of gravitationally-lensed image separations observed in
the Cosmic Lens All-Sky Survey (CLASS), the PMN-NVSS Extragalactic Lens Survey
(PANELS), the Sloan Digital Sky Survey (SDSS) and other surveys, considering a
singular isothermal ellipsoid (SIE) model for galactic potentials as well as
improved new measurements of the velocity dispersion function of galaxies based
on the SDSS DR5 data and recent semi-analytical modeling of galaxy formation,
to constrain two dark energy models (CDM and constant ) under a
flat universe assumption. We find that the current lens redshift data give a
relatively weak constraint on the model parameters. However, by combing the
redshift data with the baryonic acoustic oscillation peak and the comic
macrowave background data, we obtain more stringent results, which show that
the flat CDM model is still included at 1.Comment: 18 pages, 6 figures, 1 table, A&A accepte
Combined Effect of QCD Resummation and QED Radiative Correction to W boson Observables at the Tevatron
A precise determination of the W boson mass at the Fermilab Tevatron requires
a theoretical calculation in which the effects of the initial-state multiple
soft-gluon emission and the final-state photonic correction are simultaneously
included . Here, we present such a calculation and discuss its prediction on
the transverse mass distribution of the W boson and the transverse momentum
distribution of its decay charged lepton, which are the most relevant
observables for measuring the W boson mass at hadron colliders.Comment: 10 pages, 3 Postscript figures, uses revtex4.st
Uniqueness theorems for meromorphic mappings sharing hyperplanes in general position
The purpose of this article is to study the uniqueness problem for
meromorphic mappings from into the complex projective space
By making using of the method of dealing with
multiple values due to L. Yang and the technique of Dethloff-Quang-Tan
respectively, we obtain two general uniqueness theorems which improve and
extend some known results of meromorphic mappings sharing hyperplanes in
general position.Comment: 10 page
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