16 research outputs found
Prospects for the direct detection of neutralino dark matter in orbifold scenarios
We analyse the phenomenology of orbifold scenarios from the heterotic
superstring, and the resulting theoretical predictions for the direct detection
of neutralino dark matter. In particular, we study the parameter space of these
constructions, computing the low-energy spectrum and taking into account the
most recent experimental and astrophysical constraints, as well as imposing the
absence of dangerous charge and colour breaking minima. In the remaining
allowed regions the spin-independent part of the neutralino-proton cross
section is calculated and compared with the sensitivity of dark matter
detectors. In addition to the usual non universalities of the soft terms in
orbifold scenarios due to the modular weight dependence, we also consider
D-term contributions to scalar masses. These are generated by the presence of
an anomalous U(1), providing more flexibility in the resulting soft terms, and
are crucial in order to avoid charge and colour breaking minima. Thanks to the
D-term contribution, large neutralino detection cross sections can be found,
within the reach of projected dark matter detectors.Comment: 51 pages, 25 figure
Predicted modulated differential rates for direct WIMP searches at low energy transfers
The differential event rate for direct detection of dark matter, both the
time averaged and the modulated one due to the motion of the Earth, are
discussed. The calculations focus on relatively light cold dark matter
candidates (WIMP) and low energy transfers. It is shown that for sufficiently
light WIMPs the extraction of relatively large nucleon cross sections is
possible. Furthermore for some WIMP masses the modulation amplitude may change
sign, meaning that, in such a case, the maximum rate may occur six months later
than naively expected. This effect can be exploited to yield information about
the mass of the dark matter candidate, if and when the observation of the
modulation of the event rate is established.Comment: 16 pages, 22 figures; references adde
First measurement of nuclear recoil head-tail sense in a fiducialised WIMP dark matter detector
Recent computational results suggest that directional dark matter detectors have potential to probe for WIMP dark matter particles below the neutrino floor. The DRIFT-IId detector used in this work is a leading directional WIMP search time projection chamber detector. We report the first measurements of the detection of the directional nuclear recoils in a fully fiducialised low-pressure time projection chamber. In this new operational mode, the distance between each event vertex and the readout plane is determined by the measurement of minority carriers produced by adding a small amount of oxygen to the nominal CS + CF target gas mixture. The CS + CF + O mixture has been shown to enable background-free operation at current sensitivities. Sulfur, fluorine, and carbon recoils were generated using neutrons emitted from a Cf source positioned at different locations around the detector. Measurement of the relative energy loss along the recoil tracks allowed the track vector sense, or the so-called head-tail asymmetry parameter, to be deduced. Results show that the previously reported observation of head-tail sensitivity in pure CS is well retained after the addition of oxygen to the gas mixture
Can annihilating Dark Matter be lighter than a few GeVs?
We estimate the gamma ray fluxes from the residual annihilations of Dark
Matter particles having a mass mdm \in [MeV, O(GeV)] and compare them to
observations. We find that particles lighter than O(100 MeV) are excluded
unless their cross section is S-wave suppressed.Comment: 4 pages. No figure. Values corrected (last column Table.1). Text
clarified. Conclusions unchange
Lower limit on the neutralino mass in the general MSSM
We discuss constraints on SUSY models with non-unified gaugino masses and R_P
conservation. We derive a lower bound on the neutralino mass combining the
direct limits from LEP, the indirect limits from gmuon, bsgamma, Bsmumu and the
relic density constraint from WMAP. The lightest neutralino (mneutralino=6GeV)
is found in models with a light pseudoscalar with MA<200GeV and a large value
for . Models with heavy pseudoscalars lead to mneutralino>18(29)GeV
for . We show that even a very conservative bound from the
muon anomalous magnetic moment can increase the lower bound on the neutralino
mass in models with mu<0 and/or large values of . We then examine
the potential of the Tevatron and the direct detection experiments to probe the
SUSY models with the lightest neutralinos allowed in the context of light
pseudoscalars with high . We also examine the potential of an e+e-
collider of 500GeV to produce SUSY particles in all models with neutralinos
lighter than the W. In contrast to the mSUGRA models, observation of at least
one sparticle is not always guaranteed.Comment: 37 pages, LateX, 16 figures, paper with higher resolution figures
available at
http://wwwlapp.in2p3.fr/~boudjema/papers/bound-lsp/bound-lsp.htm
Improved Constraints on Inelastic Dark Matter
We perform an extensive study of the DAMA annual modulation data in the
context of inelastic dark matter. We find that inelastic dark matter with mass
m > 15 GeV is excluded at the 95% confidence level by the combination of DAMA
spectral information and results from other direct detection experiments.
However, at smaller m, inelastic dark matter constitutes a possible solution to
the DAMA puzzle.Comment: 22 pages, 7 figures, Reference added, matches published versio
Fitting the Gamma-Ray Spectrum from Dark Matter with DMFIT: GLAST and the Galactic Center Region
We study the potential of GLAST to unveil particle dark matter properties
with gamma-ray observations of the Galactic center region. We present full
GLAST simulations including all gamma-ray sources known to date in a region of
4 degrees around the Galactic center, in addition to the diffuse gamma-ray
background and to the dark matter signal. We introduce DMFIT, a tool that
allows one to fit gamma-ray emission from pair-annihilation of generic particle
dark matter models and to extract information on the mass, normalization and
annihilation branching ratios into Standard Model final states. We assess the
impact and systematic effects of background modeling and theoretical priors on
the reconstruction of dark matter particle properties. Our detailed simulations
demonstrate that for some well motivated supersymmetric dark matter setups with
one year of GLAST data it will be possible not only to significantly detect a
dark matter signal over background, but also to estimate the dark matter mass
and its dominant pair-annihilation mode.Comment: 37 pages, 16 figures, submitted to JCA
Inelastic Dark Matter, Non-Standard Halos and the DAMA/LIBRA Results
The DAMA collaboration have claimed to detect particle dark matter (DM) via
an annual modulation in their observed recoil event rate. This appears to be in
strong disagreement with the null results of other experiments if interpreted
in terms of elastic DM scattering, while agreement for a small region of
parameter space is possible for inelastic DM (iDM) due to the altered
kinematics of the collision. To date most analyses assume a simple galactic
halo DM velocity distribution, the Standard Halo Model, but direct experimental
support for the SHM is severely lacking and theoretical studies indicate
possible significant differences. We investigate the dependence of DAMA and the
other direct detection experiments on the local DM velocity distribution,
utilizing the results of the Via Lactea and Dark Disc numerical simulations. We
also investigate effects of varying the solar circular velocity, the DM escape
velocity, and the DAMA quenching factor within experimental limits. Our data
set includes the latest ZEPLIN-III results, as well as full publicly available
data sets. Due to the more sensitive dependence of the inelastic cross section
on the velocity distribution, we find that with Via Lactea the DAMA results can
be consistent with all other experiments over an enlarged region of iDM
parameter space, with higher mass particles being preferred, while Dark Disc
does not lead to an improvement. A definitive test of DAMA for iDM requires
heavy element detectors.Comment: 22 pages, 10 figures, PDFLaTex Additional analysis of Via Lactea
simulation include
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
WIMP dark matter, Higgs exchange and DAMA
In the WIMP scenario, there is a one-to-one relation between the dark matter
(DM) relic density and spin independent direct detection rate if both the
annihilation of DM and its elastic scattering on nuclei go dominantly through
Higgs exchange. In particular, for DM masses much smaller than the Higgs boson
mass, the ratio of the relevant cross sections depends only on the DM mass.
Assuming DM mass and direct detection rate within the ranges allowed by the
recent DAMA collaboration results -taking account of the channelling effect on
energy threshold and the null results of the other direct detection
experiments- gives a definite range for the relic density. For scalar DM
models, like the Higgs portal models or the inert doublet model, the relic
density range turns out to be in agreement with WMAP. This scenario implies
that the Higgs boson has a large branching ratio to pairs of DM particles, a
prediction which might challenge its search at the LHC.Comment: 5 pages, 5 figures. Matches the published version. One figure
modified. Conclusions unchange