143 research outputs found
Neutrino-induced Muon Fluxes from Neutralino Annihilations in the Sun and in the Earth
The flux of neutrino-induced muons at the surface of the Earth is calculated
from injection of neutralino annihilation products in the core of the Sun and
the Earth. An improved treatment of neutrino propagation through the Sun is
performed and the results are presented in an easy-to-use parameterization. For
an explicit supersymmetric model, an observable neutralino annihilation signal
is demonstrated.Comment: 4 pages, 2 figures (uuencoded compressed tar-files), uses espcrc2.st
Inert Doublet Model and LEP II Limits
The inert doublet model is a minimal extension of the standard model
introducing an additional SU(2) doublet with new scalar particles that could be
produced at accelerators. While there exists no LEP II analysis dedicated for
these inert scalars, the absence of a signal within searches for supersymmetric
neutralinos can be used to constrain the inert doublet model. This translation
however requires some care because of the different properties of the inert
scalars and the neutralinos. We investigate what restrictions an existing
DELPHI collaboration study of neutralino pair production can put on the inert
scalars and discuss the result in connection with dark matter. We find that
although an important part of the inert doublet model parameter space can be
excluded by the LEP II data, the lightest inert particle still constitutes a
valid dark matter candidate.Comment: 12 pages, 9 figures; v2: published versio
The Zero Age Main Sequence of WIMP burners
We modify a stellar structure code to estimate the effect upon the main
sequence of the accretion of weakly interacting dark matter onto stars and its
subsequent annihilation. The effect upon the stars depends upon whether the
energy generation rate from dark matter annihilation is large enough to shut
off the nuclear burning in the star. Main sequence WIMP burners look much like
protostars moving on the Hayashi track, although they are in principle
completely stable. We make some brief comments about where such stars could be
found, how they might be observed and more detailed simulations which are
currently in progress. Finally we comment on whether or not it is possible to
link the paradoxically young OB stars found at the galactic centre with WIMP
burners.Comment: 4 pages, 3 figs. Matches published versio
Neutralino Dark Matter in BMSSM Effective Theory
We study thermal neutralino dark matter in an effective field theory
extension of the MSSM, called "Beyond the MSSM" (BMSSM) in Dine, Seiberg and
Thomas (2007). In this class of effective field theories, the field content of
the MSSM is unchanged, but the little hierarchy problem is alleviated by
allowing small corrections to the Higgs/higgsino part of the Lagrangian. We
perform parameter scans and compute the dark matter relic density. The light
Higgsino LSP scenario is modified the most; we find new regions of parameter
space compared to the standard MSSM. This involves interesting interplay
between the WMAP dark matter bounds and the LEP chargino bound. We also find
some changes for gaugino LSPs, partly due to annihilation through a Higgs
resonance, and partly due to coannihilation with light stops in models that are
ruled in by the new effective terms.Comment: 37 pages + appendi
Limits on the WIMP-nucleon scattering cross-section from neutrino telescopes
Neutrino-telescopes like Super-Kamiokande and IceCube have started to explore
the neutrino fluxes from WIMP annihilations in the Sun. The non-observation of
a signal can put constraints on the WIMP properties. We here focus on the
neutrino signal from WIMP annihilation in the Sun and show that under
reasonable assumptions, the non-observation of a signal from IceCube puts a
much tighter constraint on the spin-dependent WIMP-proton scattering
cross-section than current direct detection experiments like COUPP and KIMS.
For the spin-independent scattering cross-section, the limits from IceCube and
current direct detection experiments like XENON10 and CDMS place similar
constraints. We here go through the assumptions being made and the
uncertainties that arise in converting from limits on the muon flux from the
Sun to limits on the WIMP-proton cross-section, and present our results as easy
to use conversion factors.Comment: 10 pages, 6 figures. Accepted for publication in JCA
The Role of Antimatter Searches in the Hunt for Supersymmetric Dark Matter
We analyze the antimatter yield of supersymmetric (SUSY) models with large
neutralino annihilation cross sections. We introduce three benchmark scenarios,
respectively featuring bino, wino and higgsino-like lightest neutralinos, and
we study in detail the resulting antimatter spectral features. We carry out a
systematic and transparent comparison between current and future prospects for
direct detection, neutrino telescopes and antimatter searches. We demonstrate
that often, in the models we consider, antimatter searches are the only
detection channel which already constrains the SUSY parameter space.
Particularly large antiprotons fluxes are expected for wino-like lightest
neutralinos, while significant antideuteron fluxes result from resonantly
annihilating binos. We introduce a simple and general recipe which allows to
assess the visibility of a given SUSY model at future antimatter search
facilities. We provide evidence that upcoming space-based experiments, like
PAMELA or AMS, are going to be, in many cases, the unique open road towards
dark matter discovery.Comment: 34 pages, 18 figures; V2: misprints in the labels of fig. 2,3 and 5
correcte
Early search for supersymmetric dark matter models at the LHC without missing energy
We investigate early discovery signals for supersymmetry at the Large Hadron
Collider without using information about missing transverse energy. Instead we
use cuts on the number of jets and isolated leptons (electrons and/or muons).
We work with minimal supersymmetric extensions of the standard model, and focus
on phenomenological models that give a relic density of dark matter compatible
with the WMAP measurements. An important model property for early discovery is
the presence of light sleptons, and we find that for an integrated luminosity
of only 200--300 pb at a center-of-mass energy of 10 TeV models with
gluino masses up to GeV can be tested.Comment: 28 pages, 12 figures; published versio
Model Independent Form Factors for Spin Independent Neutralino-Nucleon Scattering from Elastic Electron Scattering Data
Theoretical calculations of neutralino-nucleon interaction rates with various
nuclei are of great interest to direct dark matter searches such as CDMS,
EDELWEISS, ZEPLIN, and other experiments since they are used to establish upper
bounds on the WIMP-proton cross section. These interaction rates and cross
sections are generally computed with standard, one or two parameter
model-dependent nuclear form factors, which may not exactly mirror the actual
form factor for the particular nucleus in question. As is well known, elastic
electron scattering can allow for very precise determinations of nuclear form
factors and hence nuclear charge densities for spherical or near-spherical
nuclei. We use charge densities derived from elastic electron scattering data
to calculate model independent, analytic form factors for various target nuclei
important in dark matter searches, such as Si, Ge, S, Ca and others. We have
found that for nuclear recoils in the range of 1-100 keV significant
differences in cross sections and rates exist when the model independent form
factors are used: at 30 keV nuclear recoil the form factors squared differ by a
factor of 1.06 for Si, 1.11 for Ca, 1.27 for Ge, and 1.92
for Xe. We show the effect of different form factors on the upper limit
on the WIMP-proton cross section obtained with a hypothetical Ge
detector during a 100 kg-day effective exposure. Helm form factors with various
parameter choices differ at most by 10--20% from the best (Fourier Bessel) form
factor, and can approach it to better than 1% if the parameters are chosen to
mimic the actual nuclear density.Comment: 20 pages, 8 figure
Direct versus indirect detection in mSUGRA with self-consistent halo models
We perform a detailed analysis of the detection prospects of neutralino dark
matter in the mSUGRA framework. We focus on models with a thermal relic
density, estimated with high accuracy using the DarkSUSY package, in the range
favored by current precision cosmological measurements. Direct and indirect
detection rates are computed implementing two models for the dark matter halo,
tracing opposite regimes for the phase of baryon infall, with fully consistent
density profiles and velocity distribution functions. This has allowed, for the
first time, a fully consistent comparison between direct and indirect detection
prospects. We discuss all relevant regimes in the mSUGRA parameter space,
underlining relevant effects, and providing the basis for extending the
discussion to alternative frameworks. In general, we find that direct detection
and searches for antideuterons in the cosmic rays seems to be the most
promising ways to search for neutralinos in these scenarios.Comment: 26 pages, 9 figure
Indirect Detection of Kaluza-Klein Dark Matter from Latticized Universal Dimensions
We consider Kaluza-Klein dark matter from latticized universal dimensions. We
motivate and investigate two different lattice models, where the models differ
in the choice of boundary conditions. The models reproduce relevant features of
the continuum model for Kaluza-Klein dark matter. For the model with simple
boundary conditions, this is the case even for a model with only a few lattice
sites. We study the effects of the latticization on the differential flux of
positrons from Kaluza-Klein dark matter annihilation in the galactic halo. We
find that for different choices of the compactification radius, the
differential positron flux rapidly converges to the continuum model results as
a function of the number of lattice sites. In addition, we consider the
prospects for upcoming space-based experiments such as PAMELA and AMS-02 to
probe the latticization effect.Comment: 25 pages, 9 figures, LaTeX. Final version published in JCA
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