900 research outputs found
Constraining the Milky Way Dark Matter Density Profile with Gamma-Rays with Fermi-LAT
We study the abilities of the Fermi-LAT instrument on board of the Fermi
mission to simultaneously constrain the Milky Way dark matter density profile
and some dark matter particle properties, as annihilation cross section, mass
and branching ratio into dominant annihilation channels. A single dark matter
density profile is commonly assumed to determine the capabilities of gamma-ray
experiments to extract dark matter properties or to set limits on them.
However, our knowledge of the Milky Way halo is far from perfect, and thus in
general, the obtained results are too optimistic. Here, we study the effect
these astrophysical uncertainties would have on the determination of dark
matter particle properties and conversely, we show how gamma-ray searches could
also be used to learn about the structure of the Milky Way halo, as a
complementary tool to other type of observational data that study the
gravitational effect caused by the presence of dark matter. In addition, we
also show how these results would improve if external information on the
annihilation cross section and on the local dark matter density were included
and compare our results with the predictions from numerical simulations.Comment: 29 pages, 7 figure
Observable Medium Effects For Atmospheric Neutrinos
We discuss the possibility to observe matter effects in atmospheric neutrino
oscillations. The main conclusion is that an impact on the nu_mu survival
probability requires the action of the MSW resonance, which becomes visible for
baselines above ~7000 km. The associated muon charge asymmetry carries
information on theta_{13} and the sign of Dm^2_{31}.Comment: 7 pp, 2 fig. Talk given at the EPS-Conference on HEPP, Budapest
(Hungary), July 2001, to be published in the Proceeding
The sign of dm2_{31} and the muon-charge asymmetry for atmospheric neutrinos
We discuss the possibility to measure the sign of dm2_{31} from
matter-induced charge asymmetries in atmospheric neutrino oscillations. The
main conclusion is that an impact on the nu_mu survival probability requires
the action of the MSW resonance, which becomes visible for baselines above
\~7000 km.Comment: 6 pp, 1 fig. Talk given at the 7th International Workshop on Topics
in Astroparticles and Underground Physics (TAUP2001), Laboratori Nazionali
del Gran Sasso, Italy, September 8-12, 200
Sterile neutrino decay and the LSND experiment
We propose a new explanation of the intriguing LSND evidence for electron
antineutrino appearance in terms of heavy (mostly sterile) neutrino decay via a
coupling with a light scalar and light (mostly active) neutrinos. We perform a
fit to the LSND data, as well as all relevant null-result experiments, taking
into account the distortion of the spectrum due to decay. By requiring a
coupling g ~ 10^{-5}, a heavy neutrino mass m_4 ~ 100 keV and a mixing with
muon neutrinos |U_{mu 4}|^2 ~ 10^{-2}, we show that this model explains all
existing data evading constraints that disfavor standard (3+1) neutrino models.Comment: 3pp. Talk given at 9th International Conference on Astroparticle and
Underground Physics (TAUP 2005), Zaragoza, Spain, 10-14 Sep 200
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