2,088 research outputs found
Galactic Substructure and Energetic Neutrinos from the Sun and the Earth
We consider the effects of Galactic substructure on energetic neutrinos from
annihilation of weakly-interacting massive particles (WIMPs) that have been
captured by the Sun and Earth. Substructure gives rise to a time-varying
capture rate and thus to time variation in the annihilation rate and resulting
energetic-neutrino flux. However, there may be a time lag between the capture
and annihilation rates. The energetic-neutrino flux may then be determined by
the density of dark matter in the Solar System's past trajectory, rather than
the local density. The signature of such an effect may be sought in the ratio
of the direct- to indirect-detection rates.Comment: 4 pages, 4 figures. Replaced with version accepted for publicatio
Pseudoscalar Portal Dark Matter and New Signatures of Vector-like Fermions
Fermionic dark matter interacting with the Standard Model sector through a
pseudoscalar portal could evade the direct detection constraints while
preserving a WIMP miracle. We study the LHC constraints on the pseudoscalar
production in simplified models with the pseudoscalar either dominantly coupled
to b quarks or tau leptons and explore their implications for the GeV excesses
in gamma ray observations. We also investigate models with new vector-like
fermions that could realize the simplified models of pseudoscalar portal dark
matter. These models yield new decay channels and signatures of vector-like
fermions, for instance, bbb, btautau, and tautautau resonances. Some of the
signatures have already been strongly constrained by the existing LHC searches
and the parameter space fitting the gamma ray excess is further restricted. On
the other hand, the pure tau-rich final state is only weakly constrained so far
due to the small electroweak production rate.Comment: 18 pages, 7 figures; references added, minor modifications and match
the JHEP versio
Galactic Substructure and Dark Matter Annihilation in the Milky Way Halo
We study the effects of substructure on the rate of dark-matter annihilation
in the Galactic halo. We use an analytic model for substructure that can extend
numerical simulation results to scales too small to be resolved by the
simulations. We first calibrate the analytic model to numerical simulations,
and then determine the annihilation boost factor, for standard WIMP models as
well as those with Sommerfeld (or other) enhancements, as a function of
Galactocentric radius in the Milky Way. We provide an estimate of the
dependence of the gamma-ray intensity of WIMP annihilation as a function of
angular distance from the Galactic center. This methodology, coupled with
future numerical simulation results can be a powerful tool that can be used to
constrain WIMP properties using Fermi all-sky data.Comment: 10 pages, 7 figures, submitted to Phys. Rev. D; added a few
reference
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