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

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 $\text{bbarb}$\ and/or $\text{cbarc}$, portions of the DAMA-compatible region can be excluded if WIMP annihilations to $\text{tautau}$ and $\nu \text{anu}$ 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 $\text{bbarb}$, \ $\text{cbarc}$, \ $\text{tautau}$, \ and $\nu \text{anu}$ final states.

Comments: Replaced with revised version; Latest published results from Super-Kamiokande incorporated; quantitative limits on the branching fractions of various WIMP annihilation channels become more stringent by factors of 3 - 4; references added; overall conclusions unchanged; 17 pages, Latex, 6 Figures, accepted for publication in Phys. Rev. D