23,340 research outputs found
An extended multi-zone model for the MCG-6-30-15 warm absorber
The variable warm absorber seen with {\em ASCA} in the X-ray spectrum of
MCG6-30-15 shows complex time behaviour in which the optical depth of OVIII
anticorrelates with the flux whereas that of OVII is unchanging. The
explanation in terms of a two zone absorber has since been challenged by {\em
BeppoSAX} observations. These present a more complicated behaviour for the
OVIII edge. We demonstrate here that the presence of a third, intermediate,
zone can explain all the observations. In practice, warm absorbers are likely
to be extended, multi-zone regions of which only part causes directly
observable absorption edges at any given time.Comment: 5 pages, 6 figures, accepted for publication in MNRA
Effective 4D propagation of a charged scalar particle in Visser brane world
In this work we extend an analysis due to Visser of the effective propagation
of a neutral scalar particle on a brane world scenario which is a particular
solution of the five dimensional Einstein-Maxwell equations with cosmological
constant having an electric field pointing in the extra spatial dimension. We
determine the dispersion relations of a charged scalar particle to first order
in a perturbative analysis around those of the neutral particle. Since
depending on whether the particle is charged or not the dispersion relations
change, we could collect bulk information, namely the presence of the electric
field, by studying the 4D dynamics of the particles.Comment: 12 pages, 5 figure
Analysis of the decays induced from SUSY loops within the Mass Insertion Approximation
In this paper we study the lepton favor violating decay channels of the
neutral Higgs bosons of the Minimal Supersymmetric Standard Model into a lepton
and an anti-lepton of different flavor. We work in the context of the most
general flavor mixing scenario in the slepton sector, in contrast to the
minimal flavor violation assumption more frequently used. Our analytic
computation is a one-loop diagrammatic one, but in contrast to the full
one-loop computation which is usually referred to the physical slepton mass
basis, we use here instead the Mass Insertion Approximation (MIA) which uses
the electroweak interaction slepton basis and treats perturbatively the mass
insertions changing slepton flavor. By performing an expansion in powers of the
external momenta in the relevant form factors, we will be able to separate
explicitly in the analytic results the leading non-decoupling (constant at
asymptotically large sparticle masses) and the next to leading decoupling
contributions (decreasing with the sparticle masses). Our final aim is to
provide a set of simple analytic formulas for the form factors and the
associated effective vertices, that we think may be very useful for future
phenomenological studies of the lepton flavor violating Higgs boson decays, and
for their comparison with data. The accuracy of the numerical results obtained
with the MIA are also analyzed and discussed here in comparison with the full
one-loop results. Our most optimistic numerical estimates for the three neutral
Higgs boson decays channels into and leptons, searching for their
maximum rates that are allowed by present constraints from data and beyond Standard Model Higgs boson searches at the LHC, are
also included.Comment: 37 pages, 16 figures, 3 appendices. This version v3 matches the
manuscript published in JHE
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