Article

Neutrinos from WIMP annihilation in the Sun : Implications of a self-consistent model of the Milky Way's dark matter halo

Physical review D: Particles and fields 06/2011; DOI: 10.1103/PhysRevD.85.123533
Source: arXiv

ABSTRACT Upper limits on the spin-independent (SI) as well as spin-dependent (SD)
elastic scattering cross sections of WIMPs with protons, imposed by the
Super-Kamiokande (S-K) upper limit on the neutrino flux from WIMP annihilation
in the Sun, and their compatibility with the "DAMA-compatible" regions of the
WIMP parameter space within which the annual modulation signal observed by the
DAMA/LIBRA experiment is compatible with the null results of other direct
detection experiments, are studied within the frame work of a self-consistent
model of the finite-size dark matter (DM) halo of the Galaxy, the parameters of
which are determined by a fit to the rotation curve data of the Galaxy. We find
that the S-K implied upper limits on the WIMP-proton elastic cross section as a
function of WIMP mass impose stringent restrictions on the branching fractions
of the various WIMP annihilation channels. For SI interaction, while the S-K
upper limits are consistent with the DAMA-compatible region of the WIMP
parameter space if the WIMPs annihilate dominantly to $\bbarb$\ and/or
$\cbarc$, portions of the DAMA-compatible region can be excluded if WIMP
annihilations to $\tautau$ and $\nu\anu$ occur at larger than ~ 10% and 0.1%
levels, respectively. For SD interaction, the restrictions on the possible
annihilation channels are much more stringent, essentially ruling out the
DAMA-compatible region of the WIMP parameter space if the relatively low-mass
($\sim$ 2 -- 20 GeV) WIMPs under consideration annihilate predominantly to any
mixture of $\bbarb$, \ $\cbarc$, \ $\tautau$, \ and $\nu\anu$ final states.

0 Bookmarks
 · 
75 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The velocity distribution function (VDF) of the hypothetical Weakly Interacting Massive Particles (WIMPs), currently the most favored candidate for the Dark Matter (DM) in the Galaxy, is determined directly from the circular speed ("rotation") curve data of the Galaxy assuming isotropic VDF. This is done by "inverting" --- using Eddington's method --- the Navarro-Frenk-White universal density profile of the DM halo of the Galaxy, the parameters of which are determined, by using Markov Chain Monte Carlo (MCMC) technique, from a recently compiled set of observational data on the Galaxy's rotation curve extended to distances well beyond the visible edge of the disk of the Galaxy. The derived most-likely local isotropic VDF strongly differs from the Maxwellian form assumed in the "Standard Halo Model" (SHM) customarily used in the analysis of the results of WIMP direct-detection experiments. A parametrized (non-Maxwellian) form of the derived most-likely local VDF is given. The astrophysical "g-factor" that determines the effect of the WIMP VDF on the expected event rate in a direct-detection experiment can be lower for the derived most-likely VDF than that for the best Maxwellian fit to it by as much two orders of magnitude at the lowest WIMP mass threshold of a typical experiment.
    Physical review D: Particles and fields 10/2012; 87(8).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We consider a simple class of models in which the dark matter, X, is coupled to a new gauge boson, phi, with a relatively low mass (m_phi \sim 100 MeV-3 GeV). Neither the dark matter nor the new gauge boson have tree-level couplings to the Standard Model. The dark matter in this model annihilates to phi pairs, and for a coupling of g_X \sim 0.06 (m_X/10 GeV)^1/2 yields a thermal relic abundance consistent with the cosmological density of dark matter. The phi's produced in such annihilations decay through a small degree of kinetic mixing with the photon to combinations of Standard Model leptons and mesons. For dark matter with a mass of \sim10 GeV, the shape of the resulting gamma-ray spectrum provides a good fit to that observed from the Galactic Center, and can also provide the very hard electron spectrum required to account for the observed synchrotron emission from the Milky Way's radio filaments. For kinetic mixing near the level naively expected from loop-suppressed operators (epsilon \sim 10^{-4}), the dark matter is predicted to scatter elastically with protons with a cross section consistent with that required to accommodate the signals reported by DAMA/LIBRA, CoGeNT and CRESST-II.
    Physical review D: Particles and fields 06/2012; 86(5).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We study the impact of the assumed velocity distribution of galactic dark matter particles on the interpretation of results from nuclear recoil detectors. By converting experimental data to variables that make the astrophysical unknowns explicit, different experiments can be compared without implicit assumptions concerning the dark matter halo. We extend this framework to include the annual modulation signal, as well as multiple target elements. Recent results from DAMA, CoGeNT and CRESST-II can be brought into agreement if the velocity distribution is very anisotropic and thus allows a large modulation fraction. However constraints from CDMS and XENON cannot be evaded by appealing to such astrophysical uncertainties alone.
    Journal of Cosmology and Astroparticle Physics 11/2011; 2012(01). · 6.04 Impact Factor

Full-text (2 Sources)

View
15 Downloads
Available from
May 30, 2014