1,554 research outputs found
Indirect search for dark matter with micrOMEGAs2.4
We present a new module of micrOMEGAs devoted to the computation of indirect
signals from dark matter annihilation in any new model with a stable weakly
interacting particle. The code provides the mass spectrum, cross-sections,
relic density and exotic fluxes of gamma rays, positrons and antiprotons. The
propagation of charged particles in the Galactic halo is handled with a new
module that allows to easily modify the propagation parameters.Comment: 24 pages, 6 figures, typos corrected, acknowledgements modifie
Relic density of neutralino dark matter in the MSSM with CP violation
We calculate the relic density of dark matter in the MSSM with CP violation.
We analyse various scenarios of neutralino annihilation: the cases of a bino,
bino-wino and bino-Higgsino LSP, annihilation through Higgs, as well as
sfermion coannihilation scenarios. Large phase effects are found, on the one
hand due to shifts in the masses, on the other hand due to modifications of the
couplings. Taking special care to disentangle the effects in masses and
couplings, we demonstrate that the presence of CP phases can have a significant
influence on the neutralino relic abundance. Typical variations in \Omega h^2
solely from modifications in the couplings are O(10%-100%), but can reach an
order of magnitude in some cases.Comment: 36 pages, 21 figures (low resolution). A version with high-resolution
figures can be downloaded from http://cern.ch/kraml/papers/omc
A single hollow beam optical trap for cold atoms
We present an optical trap for atoms that we have developed for precision
spectroscopy measurements. Cold atoms are captured in a dark region of space
inside a blue-detuned hollow laser beam formed by an axicon. We analyze the
light potential in a ray optics picture and experimentally demonstrate trapping
of laser-cooled metastable xenon atoms.Comment: 12 pages, 8 figure
Search for T-violation in K^+ --> pi^0 mu^+ nu and K^+ --> mu^+ nu gamma Decays
The recent progress in search for T-violating transverse muon polarization in
the decays K^+ --> pi^0 mu^+ nu and K^+ --> mu^+ nu gamma in the on-going
experiment E246 at KEK is reported. Future prospects in polarization
measurements are also discussed.Comment: 11 pages, 5 figures, talk at the Conference of Nuclear Physics
Department RAS, 27 November - 1 December 2000, ITEP, Mosco
Light Sneutrino Dark Matter at the LHC
In supersymmetric (SUSY) models with Dirac neutrino masses, a weak-scale
trilinear A-term that is not proportional to the small neutrino Yukawa
couplings can induce a sizable mixing between left and right-handed sneutrinos.
The lighter sneutrino mass eigenstate can hence become the lightest SUSY
particle (LSP) and a viable dark matter candidate. In particular, it can be an
excellent candidate for light dark matter with mass below ~10 GeV. Such a light
mixed sneutrino LSP has a dramatic effect on SUSY signatures at the LHC, as
charginos decay dominantly into the light sneutrino plus a charged lepton, and
neutralinos decay invisibly to a neutrino plus a sneutrino. We perform a
detailed study of the LHC potential to resolve the light sneutrino dark matter
scenario by means of three representative benchmark points with different
gluino and squark mass hierarchies. We study in particular the determination of
the LSP (sneutrino) mass from cascade decays involving charginos, using the mT2
variable. Moreover, we address measurements of additional invisible sparticles,
in our case the lightest neutralino, and the question of discrimination against
the MSSM.Comment: 25 pages, 16 figure
Bosonic Quartic Couplings at LHC
We analyze the potential of the CERN Large Hadron Collider (LHC) to study
anomalous quartic vector-boson interactions Z Z gamma gamma, Z Z Z gamma, W+ W-
gamma gamma, and W+ W- Z gamma through the weak boson fusion processes q q -> q
q gamma gamma and q q -> q q gamma Z(-> l+ l-) with l = electron or muon. After
a careful study of the backgrounds and how to extract them from the data, we
show that the process p p -> j j gamma l+ l- is potentially the most sensitive
to deviations from the Standard Model, improving the sensitivity to anomalous
couplings by up to a factor 10^4 (10^2) with respect to the present direct
(indirect) limits.Comment: 18 pages, 2 figures, revised versio
Data assimilation for plume models
International audienceWe use a four-dimensional variational data assimilation (4D-VAR) algorithm to observe the growth of 2-D plumes from a point heat source. In order to test the predictability of the 4D-VAR technique for 2-D plumes, we perturb the initial conditions and compare the resulting predictions to the predictions given by a direct numerical simulation (DNS) without any 4D-VAR correction. We have studied plumes in fluids with Rayleigh numbers between 106 and 107 and Prandtl numbers between 0.7 and 70, and we find the quality of the prediction to have a definite dependence on both the Rayleigh and Prandtl numbers. As the Rayleigh number is increased, so is the quality of the prediction, due to an increase of the inertial effects in the adjoint equations for momentum and energy. The horizon predictability time, or how far into the future the 4D-VAR method can predict, decreases as Rayleigh number increases. The quality of the prediction is decreased as Prandtl number increases, however. Quality also decreases with increased prediction time
How reducing differentials in education and labor force participation could lessen workforce decline in the EU-28
Background: Population ageing is unavoidable in Europe, but perhaps its impact on labor force is not. In the context of a new demographic regime of high immigration and low fertility, differentials in labor force participation and educational attainment can be more consequential for the labor force than either the number of immigrants or structure of the overall population.
Objective: The objective of this paper is to investigate how improvements in both educational attainment (especially among children with a low educated mother or an immigration background) and labor force participation (especially of women and immigrants) could impact the future labor force in the European Union.
Methods: We used a microsimulation model called CEPAM-Mic to project the labor force of EU28 countries. CEPAM-Mic incorporates heterogeneity among different groups and allows the development of alternative scenarios concerning educational attainment and labor force participation of disadvantaged groups.
Results: Removing inequalities between subgroups in educational attainment and labor force participation drastically changes the prospective labor force size and labor force dependency ratio (LFDR) in the EU. Assuming perfect equality, the anticipated decline in the labor force size reduces by 54%, while the expected increase in the LFDR narrows by 70%.
Conclusions: Population aging is a destiny in large part driven by past demographic behaviors, but its anticipated consequences in terms of labor force size and labor force dependency ratio may be avoidable.
Contribution: This paper features a policy-oriented use of microsimulation population projections. The alternative scenarios developed go beyond traditional demographic scenarios that can only set assumptions on fertility, mortality and migration
Quartic Anomalous Couplings in Colliders
We study the constraints on the vertices ,
, and that can be obtained from
triple-gauge-boson production at the next generation of linear
colliders operating in the mode. We analyze the processes
(, or ) and show that these reactions
increase the potential of machines to search for anomalous
four-gauge-boson interactions.Comment: 15 pages, Latex file using ReVteX, 4 uufiled figures include
Implementing Dynamics of Immigration Integration in Labor Force Participation Projection in EU28
Many developed countries have turned to immigration in order to mitigate the consequences of population aging, particularly the expected decline in the labor force population. Yet, few projection models take in consideration explicitly the differentials in labor force participation of population sub-groups. This paper describes the labor force participation module of CEPAM-Mic, which is a microsimulation model that projects several demographic, ethnocultural, and socioeconomic dimensions of the EU28 member countries population. Then, the microsimulation model is used to project EU labor force population for the period 2015–2060 under different scenarios illustrating how implementing sex- and country-specific dynamics of immigrants’ integration may affect the future labor force in terms of size, rates, and gender composition. We estimated the parameters of the labor force module using logistic regressions based on the EU-Labour Force Survey (EU-LFS). In addition to age, sex, and education, immigrant-related variables are also included, such as immigrant status, place of birth, age at immigration, and duration of residence in the estimation of the probability of being active. Our results demonstrate the importance of taking into account differentials in labor force participation of population sub-groups when asserting the potential of immigration as a tool for managing population aging. In the European context, adding immigration differentials in labor force participation affects mainly downward the number of female immigrants in the labor force, while smaller differences are observed for male immigrants. An increase in immigration levels leads obviously to an increase in the total labor force size, but may also widen gender inequalities in labor force participation and has limited impact on the total labor force participation rate. Our findings suggest that relying on immigration as a tool to alleviate economic issues arising from population aging must imperatively be accompanied by strong and efficient measures to promote a full economic integration of immigrants
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