397 research outputs found
Top-quark Polarization and Asymmetries at the LHC in the Effective Description of Squark Interactions
A detailed study of top-quark polarizations and charge
asymmetries, induced by top-squark-pair production at the LHC and the
subsequent decays , is performed within the
effective description of squark interactions, which includes the effective
Yukawa couplings and another logarithmic term encoding the supersymmetry
breaking. This effective approach is more suitable for its introduction into
Monte-Carlo simulations and we make use of its implementation in {\tt MadGraph}
in order to investigate the possibilities of the charge asymmetry ,
measured at the LHC and consistent with SM expectations, to discriminate among
different SUSY scenarios and analyze the implications of these scenarios in the
top polarizations and related observables.Comment: LaTeX file. 27 pages, 6 figures, 10 tables: v3 matches published
manuscript Eur.Phys.J. C75 (2015) 1, 3
Discriminating between SUSY and Non-SUSY Higgs Sectors through the Ratio with a 125 GeV Higgs boson
It is still an open question whether the new scalar particle discovered at
the LHC with a mass of 125 GeV is the SM Higgs boson or it belongs to models of
new physics with an extended Higgs sector, as the MSSM or 2HDM. The ratio of
branching fractions = BR()/BR() of
Higgs boson decays is a powerful tool in order to distinguish the MSSM Higgs
sector from the SM or non-supersymmetric 2HDM. This ratio receives large
renormalization-scheme independent radiative corrections in supersymmetric
models at large , which are insensitive to the SUSY mass scale and
absent in the SM or 2HDM. Making use of the current LHC data and the upcoming
new results on Higgs couplings to be reported by ATLAS and CMS collaborations
and in a future linear collider, we develop a detailed and updated study of
this ratio which improves previous analyses and sets the level of accuracy
needed to discriminate between models.Comment: 11 pages, 3 figures, 1 tabl
Sensitivity to SUSY Seesaw Parameters and Lepton Flavour Violation
We address the constraints on the SUSY seesaw parameters arising from Lepton
Flavour Violation observables. Working in the Constrained Minimal
Supersymmetric Standard Model extended by three right-handed (s)neutrinos, we
study the predictions for the branching ratios of and channels. We impose compatibility with neutrino data, electric
dipole moment bounds, and further require a successful baryon asymmetry of the
Universe (via thermal leptogenesis). We emphasise the interesting interplay
between and the LFV muon decays, pointing out the hints on the
SUSY seesaw parameters that can arise from measurements of and
LFV branching ratios. This is a brief summary of the work of Ref.
\cite{Antusch:2006vw}.Comment: 6 pages, 4 figures. Presented at 5th Flavor Physics and CP Violation
Conference (FPCP 2007), Bled, Slovenia, 12-16 May 200
Testing Supersymmetry with Lepton Flavor Violating tau and mu decays
In this work the following lepton flavor violating and decays
are studied: , , , , and . We work in a supersymmetric scenario consisting of the minimal
supersymmetric standard model particle content, extended by the addition of
three heavy right handed Majorana neutrinos and their supersymmetric partners,
and where the generation of neutrino masses is done via the seesaw mechanism.
Within this context, a significant lepton flavor mixing is generated in the
slepton sector due to the Yukawa neutrino couplings, which is transmited from
the high to the low energies via the renormalization group equations. This
slepton mixing then generates via loops of supersymmetric particles significant
contributions to the rates of and the correlated decays. We analize here in full detail these rates in terms of the
relevant input parameters, which are the usual minimal supergravity parameters
and the seesaw parameters. For the decays, a full one-loop
analytical computation of all the contributing supersymmetric loops is
presented. This completes and corrects previous computations in the literature.
In the numerical analysis compatibility with the most recent experimental upper
bounds on all these and decays, with the neutrino data, and with
the present lower bounds on the supersymmetric particle masses are required.
Two typical scenarios with degenerate and hierarchical heavy neutrinos are
considered. We will show here that the minimal supergravity and seesaw
parameters do get important restrictions from these and decays in
the hierarchical neutrino case.Comment: Version to appear in Physical Review
Enhancing lepton flavour violation in the supersymmetric inverse seesaw beyond the dipole contribution
In minimal supersymmetric models the -penguin usually provides
sub-dominant contributions to charged lepton flavour violating observables. In
this study, we consider the supersymmetric inverse seesaw in which the
non-minimal particle content allows for dominant contributions of the
-penguin to several lepton flavour violating observables. In particular, and
due to the low-scale (TeV) seesaw, the penguin contribution to, for instance,
\Br(\mu \to 3e) and conversion in nuclei, allows to render some of
these observables within future sensitivity reach. Moreover, we show that in
this framework, the -penguin exhibits the same non-decoupling behaviour
which had previously been identified in flavour violating Higgs decays in the
Minimal Supersymmetric Standard Model.Comment: 29 pages, 9 figures, 4 tables; v2: minor corrections, version to
appear in JHE
A common rule for decision-making in animal collectives across species
A diversity of decision-making systems has been observed in animal
collectives. In some species, choices depend on the differences of the numbers
of animals that have chosen each of the available options, while in other
species on the relative differences (a behavior known as Weber's law) or follow
more complex rules. We here show that this diversity of decision systems
corresponds to a single rule of decision-making in collectives. We first
obtained a decision rule based on Bayesian estimation that uses the information
provided by the behaviors of the other individuals to improve the estimation of
the structure of the world. We then tested this rule in decision experiments
using zebrafish (Danio rerio), and in existing rich datasets of argentine ants
(Linepithema humile) and sticklebacks (Gasterosteus aculeatus), showing that a
unified model across species can quantitatively explain the diversity of
decision systems. Further, these results show that the different counting
systems used by animals, including humans, can emerge from the common principle
of using social information to make good decisions
Consistent and elastic registration of histological sections using vector-spline regularization
The final publication is available at Springer via http://dx.doi.org/10.1007/11889762_8Revised Papers on Second International ECCV Workshop, CVAMIA 2006 Graz, Austria, May 12, 2006Here we present a new image registration algorithm for the alignment of histological sections that combines the ideas of B-spline based elastic registration and consistent image registration, to allow simultaneous registration of images in two directions (direct and inverse). In principle, deformations based on B-splines are not invertible. The consistency term overcomes this limitation and allows registration of two images in a completely symmetric way. This extension of the elastic registration method simplifies the search for the optimum deformation and allows registering with no information about landmarks or deformation regularization. This approach can also be used as the first step to solve the problem of group-wise registration.Ignacio Arganda-Carreras is being supported by a predoctoral FPI-CAM fellow-
ship since October 2003. Carlos Ortiz-de-Solorzano is supported by a Ramon y
Cajal (Spanish Ministry of Education and Science ryc-2004-002353) and a Marie
Curie International Reintegration Grant (FP6-518688). Jan Kybic was sponsored
by the Czech Ministery of Education under project number MSM210000012. Par-
tial support is acknowledged to Comunidad de Madrid through grant GR/SAL/0234,
to Instituto de Salud Carlos III-Fondo de Investigaciones Sanitarias (FIS) through
the IM3 Network and grant 040683 and to the Plan Nacional de Investigación
Científica, Desarrollo e Innovación Tecnológica (I+D+I)
Lepton flavor violating Higgs boson decays from massive seesaw neutrinos
Lepton flavor violating Higgs boson decays are studied within the context of
seesaw models with Majorana massive neutrinos. Two models are considered: The
SM-seesaw, with the Standard Model Particle content plus three right handed
neutrinos, and the MSSM-seesaw, with the Minimal Supersymmetric Standard Model
particle content plus three right handed neutrinos and their supersymmetric
partners. The widths for these decays are derived from a full one-loop
diagrammatic computation in both models, and they are analyzed numerically in
terms of the seesaw parameters, namely, the Dirac and Majorana mass matrices.
Several possible scenarios for these mass matrices that are compatible with
neutrino data are considered. In the SM-seesaw case, very small branching
ratios are found for all studied scenarios. These ratios are explained as a
consequence of the decoupling behaviour of the heavy right handed neutrinos. In
contrast, in the MSSM-seesaw case, sizeable branching ratios are found for some
of the leptonic flavor violating decays of the MSSM neutral Higgs bosons and
for some choices of the seesaw matrices and MSSM parameters. The relevance of
the two competing sources of lepton flavor changing interactions in the
MSSM-seesaw case is also discussed. The non-decoupling behaviour of the
supersymmetric particles contributing in the loop-diagrams is finally shown.Comment: 44pgs. Version to appear in Phys.Rev.
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