Inelastic Dark Matter, Non-Standard Halos and the DAMA/LIBRA Results
ArXiv 0812.1931 (2008)
Authors:
John March-Russell, Christopher McCabe, Matthew McCullough
Abstract:
The DAMA collaboration have claimed to detect particle dark matter (DM) via
an annual modulation in their observed recoil event rate. This appears to be in
strong disagreement with the null results of other experiments if interpreted
in terms of elastic DM scattering, while agreement for a small region of
parameter space is possible for inelastic DM (iDM) due to the altered
kinematics of the collision. To date most analyses assume a simple galactic
halo DM velocity distribution, the Standard Halo Model, but direct experimental
support for the SHM is severely lacking and theoretical studies indicate
possible significant differences. We investigate the dependence of DAMA and the
other direct detection experiments on the local DM velocity distribution,
utilizing the results of the Via Lactea and Dark Disc numerical simulations. We
also investigate effects of varying the solar circular velocity, the DM escape
velocity, and the DAMA quenching factor within experimental limits. Our data
set includes the latest ZEPLIN-III results, as well as full publicly available
data sets. Due to the more sensitive dependence of the inelastic cross section
on the velocity distribution, we find that with Via Lactea the DAMA results can
be consistent with all other experiments over an enlarged region of iDM
parameter space, with higher mass particles being preferred, while Dark Disc
does not lead to an improvement. A definitive test of DAMA for iDM requires
heavy element detectors.
