6,422 research outputs found
Dark matter and neutrino masses in the R-parity violating NMSSM
The R-Parity symmetry Violating (RPV) version of the Next-to-Minimal
Supersymmetric Standard Model (NMSSM) is attractive simultaneously with regard
to the so-called mu-problem and the accommodation of three-flavor neutrino data
at tree level. In this context, we show here that if the Lightest
Supersymmetric Particle (LSP) is the gravitino, it possesses a lifetime larger
than the age of the universe since its RPV induced decay channels are
suppressed by the weak gravitational strength. This conclusion holds if one
considers gravitino masses ~ 10^2 GeV like in supergravity scenarios, and is
robust if the lightest pseudoscalar Higgs field is as light as ~ 10 GeV [as may
occur in the NMSSM]. For these models predicting in particular an RPV
neutrino-photino mixing, the gravitino lifetime exceeds the age of the universe
by two orders of magnitude. However, we find that the gravitino cannot
constitute a viable dark matter candidate since its too large RPV decay widths
would then conflict with the flux data of last indirect detection experiments.
The cases of a sneutrino LSP or a neutralino LSP as well as the more promising
gauge-mediated supersymmetry breaking scenario are also discussed. Both the
one-flavor simplification hypothesis and the realistic scenario of three
neutrino flavors are analyzed. We have modified the NMHDECAY program to extend
the neutralino mass matrix to the present framework.Comment: Latex file, 23 pages, 7 figures. References added and discussion on
the indirect detection modifie
Simulation of Entangled Polymer Solutions
We present a computer simulation of entangled polymer solutions at
equilibrium. The chains repel each other via a soft Gaussian potential,
appropriate for semi-dilute solutions at the scale of a correlation blob. The
key innovation to suppress chain crossings is to use a pseudo-continuous model
of a backbone which effectively leaves no gaps between consecutive points on
the chain, unlike the usual bead-and-spring model. Our algorithm is
sufficiently fast to observe the entangled regime using a standard desktop
computer. The simulated structural and mechanical correlations are in fair
agreement with the expected predictions for a semi-dilute solution of entangled
chains
On the precision of estimation of genetic distance
This article gives a formal proof of a formula for the precision of estimated genetic distances proposed by Barker et al. which can be used in designing experimental sampling programmes. The derivation is given in the general multiallelic case using the Sanghvi distance. Two sources of sampling are considered, i.e. i) among individuals (or gametes) within locus and ii) among loci within populations. Distribution assumptions about gene frequencies are discussed, especially the normal used in Barker et al. versus the Dirichlet via simulation
Design to reliability shielded vertical interconnection applied to microwave Chip Scale Packaging
This paper presents the electrical design, measurement and reliability ests of a shielded vertical interconnection dedicated to microwave solder-mount packages. Electromagnetic simulations show very good results up to 20 GHz. Test samples have been designed and manufactured. Electrical results are in accordance with the simulations with insertion loss lower than 0.1 dB up to 20 GHz for the proposed interconnection. Reliability tests of present no degradation of the after 500 thermal cycles in the [-55°C, +125°C] temperature range
Aide publique au développement et transition fiscale
This paper aims to analyze the impact of official development assistance (ODA) on tax transition in developing countries. First, we build qualitative indicators of tax transition taking into account the level as well as the composition of public revenue. Second, we provide theoretical explanations of how ODA can affect tax transition in an environment characterized by several divergent social interests. Te third step consists in econometrically analyzing the relationship between official development assistance and tax transition. Basing our estimates on a sample consisted of 106 developing countries over the period 1980-2005, we find that official development assistance significantly accelerates the transition and even more sustains it for at least five years. This result is robust to several specifications based on alternative measures of both foreign aid and tax transition
Assessment of Nitrogen Nutrition Status of Grasses under Water Deficit and Recovery
Grasslands are rarely irrigated. They are therefore systematically submitted to more or less severe water deficits: as well as mineral deficiencies, water scarcity often also results in a reduction of nitrogen (N) status. Although identified some time ago, qualitatively, the interaction with N still remains difficult to take into account in quantitative analyses of crop physiology under water deficits. This paper illustrates how the nitrogen (N) status of the crop changes under water deficits. A N nutrition index (INN) was defined as the ratio of the actual N concentration of forage with the theoretical N concentration under optimal conditions, the latter only depending on the above ground biomass. The objective of the paper is to describe the effect of water deficits on INN, using a new assay recently proposed by Faruggia et al. ( 2004)
GMF: A Model Migration Case for the Transformation Tool Contest
Using a real-life evolution taken from the Graphical Modeling Framework, we
invite submissions to explore ways in which model transformation and migration
tools can be used to migrate models in response to metamodel adaptation.Comment: In Proceedings TTC 2011, arXiv:1111.440
Experimental Demonstration of A Dual-Input/Dual-Output Reflective Impedance Metasurface
This paper presents the experimental demonstration of a
dual-input/dual-output reflective impedance metasurface. The design of the
metasurface relies on the Method of Moments and leverages auxiliary surface
waves to achieve anomalous reflection of two impinging plane waves with
controlled sidelobe levels. The two beams are chosen independently compared to
those in a conventional phase-gradient metasurface where the design presents a
single slope to achieve a certain reflection and all other incident beams would
depend on that slope. A prototype that ensures maximum directivity at two
prescribed reflection angles for the two input waves is then fabricated on a
Rogers RO3003 printed-circuit board using 42 metawires loaded with printed
capacitors. The proposed metasurface is capable of reflecting an incident beam
from to and a second from to at
9.93 GHz. The metasurface is experimentally characterized and an illumination
efficiency of at least 89% is calculated for each of the reflected waves,
indicating a high multiplexing efficacy
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