72 research outputs found
Halo independent comparison of direct dark matter detection data
We extend the halo-independent method of Fox, Liu, and Weiner to include
energy resolution and efficiency with arbitrary energy dependence, making it
more suitable for experiments to use in presenting their results. Then we
compare measurements and upper limits on the direct detection of low mass
( GeV) weakly interacting massive particles with spin-independent
interactions, including the upper limit on the annual modulation amplitude from
the CDMS collaboration. We find that isospin-symmetric couplings are severely
constrained both by XENON100 and CDMS bounds, and that isospin-violating
couplings are still possible at the lowest energies, while the tension of the
higher energy CoGeNT bins with the CDMS modulation constraint remains. We find
the CRESST II signal is not compatible with the modulation signals of DAMA and
CoGeNT.Comment: version slightly longer than the first, with 3 additional figures and
the latest XENON100 bound added. 7 pages, 5 figure
Relic Abundance of Asymmetric Dark Matter
We investigate the relic abundance of asymmetric Dark Matter particles that
were in thermal equilibrium in the early universe. The standard analytic
calculation of the symmetric Dark Matter is generalized to the asymmetric case.
We calculate the asymmetry required to explain the observed Dark Matter relic
abundance as a function of the annihilation cross section. We show that
introducing an asymmetry always reduces the indirect detection signal from WIMP
annihilation, although it has a larger annihilation cross section than
symmetric Dark Matter. This opens new possibilities for the construction of
realistic models of MeV Dark Matter.Comment: 20 pages, 11 figures, Accepted by JCA
Superweakly interacting dark matter from the Minimal Walking Technicolor
We study a superweakly interacting dark matter particle motivated by minimal
walking technicolor theories. Our WIMP is a mixture of a sterile state and a
state with the charges of a standard model fourth family neutrino. We show that
the model can give the right amount of dark matter over a range of the WIMP
mass and mixing angle. We compute bounds on the model parameters from the
current accelerator data including the oblique corrections to the precision
electroweak parameters, as well as from cryogenic experiments, Super-Kamiokande
and from the IceCube experiment. We show that consistent dark matter solutions
exist which satisfy all current constraints. However, almost the entire
parameter range of the model lies within the the combined reach of the next
generation experiments.Comment: 29 pages, 6 figure
On the annual modulation signal in dark matter direct detection
We derive constraints on the annual modulation signal in Dark Matter (DM)
direct detection experiments in terms of the unmodulated event rate. A general
bound independent of the details of DM distribution follows from the assumption
that the motion of the earth around the sun is the only source of time
variation. The bound is valid for a very general class of particle physics
models and also holds in the presence of an unknown unmodulated background.
More stringent bounds are obtained, if modest assumptions on symmetry
properties of the DM halo are adopted. We illustrate the bounds by applying
them to the annual modulation signals reported by the DAMA and CoGeNT
experiments in the framework of spin-independent elastic scattering. While the
DAMA signal satisfies our bounds, severe restrictions on the DM mass can be set
for CoGeNT.Comment: discussion of CoGeNT surface event subtraction added, improved
statistical analysis, version to appear in JCAP, 29 pages, 9 figures, 3
appendice
Dark Matter attempts for CoGeNT and DAMA
Recently, the CoGeNT collaboration presented a positive signal for an annual
modulation in their data set. In light of the long standing annual modulation
signal in DAMA/LIBRA, we analyze the compatibility of both of these signal
within the hypothesis of dark matter (DM) scattering on nuclei, taking into
account existing experimental constraints. We consider the cases of elastic and
inelastic scattering with either spin-dependent or spin-independent coupling to
nucleons. We allow for isospin violating interactions as well as for light
mediators. We find that there is some tension between the size of the
modulation signal and the time-integrated event excess in CoGeNT, making it
difficult to explain both simultaneously. Moreover, within the wide range of DM
interaction models considered, we do not find a simultaneous explanation of
CoGeNT and DAMA/LIBRA compatible with constraints from other experiments.
However, in certain cases part of the data can be made consistent. For example,
the modulation signal from CoGeNT becomes consistent with the total rate and
with limits from other DM searches at 90% CL (but not with the DAMA/LIBRA
signal) if DM scattering is inelastic spin-independent with just the right
couplings to protons and neutrons to reduce the scattering rate on xenon.
Conversely the DAMA/LIBRA signal (but not CoGeNT) can be explained by
spin-dependent inelastic DM scattering.Comment: 20 pages, 9 figure
Simulated Milky Way analogues: implications for dark matter direct searches
We study the implications of galaxy formation on dark matter direct detection using high resolution hydrodynamic simulations of Milky Way-like galaxies simulated within the eagle and apostle projects. We identify MilkyWay analogues that satisfy observational constraints on the Milky Way rotation curve and total stellar mass. We then extract the dark matter density and velocity distribution in the Solar neighbourhood for this set of Milky Way analogues, and use them to analyse the results of current direct detection experiments. For most Milky Way analogues, the event rates in direct detection experiments obtained from the best _t Maxwellian distribution (with peak speed of 223 { 289 km=s) are similar to those obtained directly from the simulations. As a consequence, the allowed regions and exclusion limits set by direct detection experiments in the dark matter mass and spin-independent cross section plane shift by a few GeV compared to the Standard Halo Model, at low dark matter masses. For each dark matter mass, the halo-to-halo variation of the local dark matter density results in an overall shift of the allowed regions and exclusion limits for the cross section. However, the compatibility of the possible hints for a dark matter signal from
DAMA and CDMS-Si and null results from LUX and SuperCDMS is not improved
Probing the Local Velocity Distribution of WIMP Dark Matter with Directional Detectors
We explore the ability of directional nuclear-recoil detectors to constrain
the local velocity distribution of weakly interacting massive particle (WIMP)
dark matter by performing Bayesian parameter estimation on simulated
recoil-event data sets. We discuss in detail how directional information, when
combined with measurements of the recoil-energy spectrum, helps break
degeneracies in the velocity-distribution parameters. We also consider the
possibility that velocity structures such as cold tidal streams or a dark disk
may also be present in addition to the Galactic halo. Assuming a
carbon-tetrafluoride detector with a 30-kg-yr exposure, a 50-GeV WIMP mass, and
a WIMP-nucleon spin-dependent cross-section of 0.001 pb, we show that the
properties of a cold tidal stream may be well constrained. However, measurement
of the parameters of a dark-disk component with a low lag speed of ~50 km/s may
be challenging unless energy thresholds are improved.Comment: 38 pages, 15 figure
Pseudo Goldstone Bosons Phenomenology in Minimal Walking Technicolor
We construct the non-linear realized Lagrangian for the Goldstone Bosons
associated to the breaking pattern of SU(4) to SO(4). This pattern is expected
to occur in any Technicolor extension of the standard model featuring two Dirac
fermions transforming according to real representations of the underlying gauge
group. We concentrate on the Minimal Walking Technicolor quantum number
assignments with respect to the standard model symmetries. We demonstrate that
for, any choice of the quantum numbers, consistent with gauge and Witten
anomalies the spectrum of the pseudo Goldstone Bosons contains electrically
doubly charged states which can be discovered at the Large Hadron Collider.Comment: 25 pages, 5 figure
Charge Asymmetric Cosmic Rays as a probe of Flavor Violating Asymmetric Dark Matter
The recently introduced cosmic sum rules combine the data from PAMELA and
Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate
whether the experimentally observed lepton excesses violate charge symmetry.
One can in a simple way determine universal properties of the unknown component
of the cosmic rays. Here we attribute a potential charge asymmetry to the dark
sector. In particular we provide models of asymmetric dark matter able to
produce charge asymmetric cosmic rays. We consider spin zero, spin one and spin
one-half decaying dark matter candidates. We show that lepton flavor violation
and asymmetric dark matter are both required to have a charge asymmetry in the
cosmic ray lepton excesses. Therefore, an experimental evidence of charge
asymmetry in the cosmic ray lepton excesses implies that dark matter is
asymmetric.Comment: 12 pages, 8 figures. Revised version to match the published versio
Resolution of dark matter problem in f(T) gravity
In this paper, we attempt to resolve the dark matter problem in f(T) gravity.
Specifically, from our model we successfully obtain the flat rotation curves of
galaxies containing dark matter. Further, we obtain the density profile of dark
matter in galaxies. Comparison of our analytical results shows that our
torsion-based toy model for dark matter is in good agreement with empirical
data-based models. It shows that we can address the dark matter as an effect of
torsion of the space.Comment: 14 pages, 3 figure
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