1,449 research outputs found
Self-interacting Dark Matter Benchmarks
Dark matter self-interactions have important implications for the
distributions of dark matter in the Universe, from dwarf galaxies to galaxy
clusters. We present benchmark models that illustrate characteristic features
of dark matter that is self-interacting through a new light mediator. These
models have self-interactions large enough to change dark matter densities in
the centers of galaxies in accord with observations, while remaining compatible
with large-scale structure data and all astrophysical observations such as halo
shapes and the Bullet Cluster. These observations favor a mediator mass in the
10 - 100 MeV range and large regions of this parameter space are accessible to
direct detection experiments like LUX, SuperCDMS, and XENON1T.Comment: 4 pages, white paper for Snowmass 2013; v2: finalized version,
figures correcte
Neutron stars at the dark matter direct detection frontier
Neutron stars capture dark matter efficiently. The kinetic energy transferred
during capture heats old neutron stars in the local galactic halo to
temperatures detectable by upcoming infrared telescopes. We derive the
sensitivity of this probe in the framework of effective operators. For dark
matter heavier than a GeV, we find that neutron star heating can set limits on
the effective operator cutoff that are orders of magnitude stronger than
possible from terrestrial direct detection experiments in the case of
spin-dependent and velocity-suppressed scattering.Comment: 6 pages, 3 figure
Direct Detection Portals for Self-interacting Dark Matter
Dark matter self-interactions can affect the small scale structure of the
Universe, reducing the central densities of dwarfs and low surface brightness
galaxies in accord with observations. From a particle physics point of view,
this points toward the existence of a 1-100 MeV particle in the dark sector
that mediates self-interactions. Since mediator particles will generically
couple to the Standard Model, direct detection experiments provide sensitive
probes of self-interacting dark matter. We consider three minimal mechanisms
for coupling the dark and visible sectors: photon kinetic mixing, Z boson mass
mixing, and the Higgs portal. Self-interacting dark matter motivates a new
benchmark paradigm for direct detection via momentum-dependent interactions,
and ton-scale experiments will cover astrophysically motivated parameter
regimes that are unconstrained by current limits. Direct detection is a
complementary avenue to constrain velocity-dependent self-interactions that
evade astrophysical bounds from larger scales, such as those from the Bullet
Cluster.Comment: 18 pages, 7 figure
Galactic Center Excess in Gamma Rays from Annihilation of Self-Interacting Dark Matter
Observations by the Fermi-LAT telescope have uncovered a significant
-ray excess toward the Milky Way Galactic Center. There has been no
detection of a similar signal in the direction of the Milky Way dwarf
spheroidal galaxies. Additionally, astronomical observations indicate that
dwarf galaxies and other faint galaxies are less dense than predicted by the
simplest cold dark matter models. We show that a self-interacting dark matter
model with a particle mass of roughly 50 GeV annihilating to the mediator
responsible for the strong self-interaction can simultaneously explain all
three observations. The mediator is necessarily unstable and its mass must be
below about 100 MeV in order to lower densities in faint galaxies. If the
mediator decays to electron-positron pairs with a cross section on the order of
the thermal relic value, then we find that these pairs can up-scatter the
interstellar radiation field and produce the observed -ray excess. We
show that this model is compatible with all current constraints and highlight
detectable signatures unique to self-interacting dark matter models.Comment: 6 pages, 4 figure
Confluence of Constraints in Gauge Mediation: The 125 GeV Higgs Boson and Goldilocks Cosmology
Recent indications of a 125 GeV Higgs boson are challenging for
gauge-mediated supersymmetry breaking (GMSB), since radiative contributions to
the Higgs boson mass are not enhanced by significant stop mixing. This
challenge should not be considered in isolation, however, as GMSB also
generically suffers from two other problems: unsuppressed electric dipole
moments and the absence of an attractive dark matter candidate. We show that
all of these problems may be simultaneously solved by considering heavy
superpartners, without extra fields or modified cosmology. Multi-TeV sfermions
suppress the EDMs and raise the Higgs mass, and the dark matter problem is
solved by Goldilocks cosmology, in which TeV neutralinos decay to GeV
gravitinos that are simultaneously light enough to solve the flavor problem and
heavy enough to be all of dark matter. The implications for collider searches
and direct and indirect dark matter detection are sobering, but EDMs are
expected near their current bounds, and the resulting non-thermal gravitino
dark matter is necessarily warm, with testable cosmological implications.Comment: pdflatex, 15 pages, 11 figure
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