6,950 research outputs found
Compositeness Effects in the Anomalous Weak-Magnetic Moment of Leptons
We investigate the effects induced by excited leptons, at the one-loop level,
in the anomalous magnetic and weak-magnetic form factors of the leptons. Using
a general effective Lagrangian approach to describe the couplings of the
excited leptons, we compute their contributions to the weak-magnetic moment of
the lepton, which can be measured on the peak, and we compare it
with the contributions to , measured at low energies.Comment: Latex File using Rev Tex. 16 pages 5 .eps figure
Standard Model: An Introduction
We present a primer on the Standard Model of the electroweak interaction.
Emphasis is given to the historical aspects of the theory's formulation. The
radiative corrections to the Standard Model are presented and its predictions
for the electroweak parameters are compared with the precise experimental data
obtained at the Z pole. Finally, we make some remarks on the perspectives for
the discovery of the Higgs boson, the most important challenge of the Standard
Model.Comment: 101 pages, 14 figures, To be published in "Particle and Fields",
Proceedings of the X J. A. Swieca Summer School (World Scientific, Singapore,
2000
Qualitative Analysis of Polycycles in Filippov Systems
In this paper, we are concerned about the qualitative behaviour of planar
Filippov systems around some typical minimal sets, namely, polycycles. In the
smooth context, a polycycle is a simple closed curve composed by a collection
of singularities and regular orbits, inducing a first return map. Here, this
concept is extended to Filippov systems by allowing typical singularities lying
on the switching manifold. Our main goal consists in developing a method to
investigate the unfolding of polycycles in Filippov systems. In addition, we
applied this method to describe bifurcation diagrams of Filippov systems around
certain polycycles
Fermion Helicity Flip in Weak Gravitational Fields
The helicity flip of a spin- Dirac particle
interacting gravitationally with a scalar field is analyzed in the context of
linearized quantum gravity. It is shown that massive fermions may have their
helicity flipped by gravity, in opposition to massless fermions which preserve
their helicity.Comment: RevTeX 3.0, 8 pages, 3 figures (available upon request), Preprint
IFT-P.013/9
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