2,488 research outputs found
Constraints to Dark Matter from Inert Higgs Doublet Model
We study the Inert Higgs Doublet Model and its inert scalar Higgs as the
only source for dark matter. It is found that three mass regions of the inert
scalar Higgs can give the correct dark matter relic density. The low mass
region (between 3 and 50 GeV) is ruled out. New direct dark matter detection
experiments will probe the intermediate (between 60 and 100 GeV) and high
(heavier than 550 GeV) mass regions. Collider experiments are advised to search
for decay in the two jets plus missing energy channel
Non-diagonal Charged Lepton Yukawa Matrix: Effects on Neutrino Mixing in Supersymmetry
Generally the diagonalization of the mass matrix of the charged leptons is a
part of the neutrino UPMNS matrix. However, usually this contribution is
ignored by assuming a diagonal mass matrix for charged leptons. In this letter
we test this common assumption in the context of neutrino physics. Our
analytical and numerical results for two supersymmetric models reveal that such
a simplification is not justified. Especially for the solar and reactor mixing
angles important modifications are found.Comment: 22 pages 8 figure
Gravity Effects on Neutrino Masses in Split Supersymmetry
The mass differences and mixing angles of neutrinos can neither be explained
by R-Parity violating split supersymmetry nor by flavor blind quantum gravity
alone. It is shown that combining both effects leads, within the allowed
parameter range, to good agreement with the experimental results. The
atmospheric mass is generated by supersymmetry through mixing between neutrinos
and neutralinos, while the solar mass is generated by gravity through flavor
blind dimension five operators. Maximal atmospheric mixing forces the tangent
squared of the solar angle to be equal to 1/2. The scale of the quantum gravity
operator is predicted within a 5% error, implying that the reduced Planck scale
should lie around the GUT scale. In this way, the model is very predictive and
can be tested at future experiments.Comment: 12 pages, 9 figures; In section 3 we extend our discussion about the
definition of flavor basis in order to clarify in which basis the Gravity
contributions are flavor blind. In the section 4 we add some words to explain
why the Gravity contributions will not affect the charged lepton mass matrix;
Finally we also fixed some minor typos regarding units or plot label
Comparing contact and dipolar interaction in a Bose-Einstein condensate
We have measured the relative strength of the magnetic
dipole-dipole interaction compared to the contact interaction in a chromium
Bose-Einstein condensate. We analyze the asymptotic velocities of expansion of
a dipolar chromium BEC with different orientations of the atomic magnetic
dipole moments. By comparing them with numerical solutions of the hydrodynamic
equations for dipolar condensates, we are able to determine with high accuracy. Since the absolute strength of the
dipole-dipole interaction is known exactly, the relative strength of the
dipoledipole interaction can be used to determine the s-wave scattering length
of 52Cr. This is fully consistent
with our previous measurements on the basis of Feshbach resonances
Assessing water availability in Mediterranean regions affected by water conflicts through MODIS data time series analysis
Water scarcity is a widespread problem in arid and semi-arid regions such as the western Mediterranean coastal areas. The irregularity of the precipitation generates frequent droughts that exacerbate the conflicts among agriculture, water supply and water demands for ecosystems maintenance. Besides, global climate models predict that climate change will cause Mediterranean arid and semi-arid regions to shift towards lower rainfall scenarios that may exacerbate water conflicts. The purpose of this study is to find a feasible methodology to assess current and monitor future water demands in order to better allocate limited water resources. The interdependency between a vegetation index (NDVI), land surface temperature (LST), precipitation (current and future), and surface water resources availability in two watersheds in southeastern Spain with serious difficulties in meeting water demands was investigated. MODIS (Moderate Resolution Imaging Spectroradiometer) NDVI and LST products (as proxy of drought), precipitation maps (generated from climate station records) and reservoir storage gauging information were used to compute times series anomalies from 2001 to 2014 and generate regression images and spatial regression models. The temporal relationship between reservoir storage and time series of satellite images allowed the detection of different and contrasting water management practices in the two watersheds. In addition, a comparison of current precipitation rates and future precipitation conditions obtained from global climate models suggests high precipitation reductions, especially in areas that have the potential to contribute significantly to groundwater storage and surface runoff, and are thus critical to reservoir storage. Finally, spatial regression models minimized spatial autocorrelation effects, and their results suggested the great potential of our methodology combining NDVI and LST time series to predict future scenarios of water scarcity.Published versio
Asymmetry of parietal interhemispheric connections in humans
Visuospatial abilities are preferentially mediated by the right hemisphere. Although this asymmetry of function is thought to be due to an unbalanced interaction between cerebral hemispheres, the underlying neurophysiological substrate is still largely unknown. Here, using a method of trifocal transcranial magnetic stimulation, we show that the right, but not left, human posterior parietal cortex exerts a strong inhibitory activity over the contralateral homologous area by a short-latency connection. We also clarify, using diffusion-tensor magnetic resonance imaging, that such an interaction is mediated by direct transcallosal projections located in the posterior corpus callosum. We argue that this anatomo-functional network may represent a possible neurophysiological basis for the ongoing functional asymmetry between parietal cortices, and that its damage could contribute to the clinical manifestations of neglect
Gravitino Dark Matter and Neutrino Masses in Partial Split Supersymmetry
Partial Split Supersymmetry with bilinear R-parity violation allows to
reproduce all neutrino mass and mixing parameters. The viable dark matter
candidate in this model is the gravitino. We study the hypothesis that both
possibilities are true: Partial Split Supersymmetry explains neutrino physics
and that dark matter is actually composed of gravitinos. Since the gravitino
has a small but non-zero decay probability, its decay products could be
observed in astrophysical experiments. Combining bounds from astrophysical
photon spectra with the bounds coming from the mass matrix in the neutrino
sector we derive a stringent upper limit for the allowed gravitino mass. This
mass limit is in good agreement with the results of direct dark matter
searches.Comment: 22 pages, 3 figure
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