Compatibility of DAMA/LIBRA dark matter detection with other searches
Abstract
The DAMA/NaI and DAMA/LIBRA annual modulation data, which may be interpreted as a signal for the existence of weakly interacting dark matter (WIMPs) in our galactic halo, are examined in light of null results from other experiments. We use the energy spectrum of the combined DAMA modulation data given in 36 bins, and include the effect of channeling. Several statistical tools are implemented in our study: likelihood ratio with a global fit and with raster scans in the WIMP mass and goodness-of-fit (g.o.f.). These approaches allow us to differentiate between the preferred (global fit) and allowed (g.o.f.) parameter regions. For spin-independent (SI) interactions, the preferred DAMA regions are ruled out to the 3$\sigma$ C.L., even with channeling taken into account. However, for WIMP masses of ~10 GeV some parameters outside these regions still yield a reasonable fit to the DAMA data and are compatible with all 90% C.L. upper limits from negative searches, when channeling is included. For spin-dependent (SD) interactions with neutron-only couplings we find parameters within the 3$\sigma$ C.L. allowed DAMA region for 7-9 GeV WIMP masses that satisfy other experimental constraints when channeling is included. For SD proton-only couplings, a range of masses below 10 GeV is compatible with DAMA and other experiments, with and without channeling, when Super-Kamiokande (SuperK) indirect detection constraints are included; without the SuperK constraints, masses as high as 70 GeV are compatible. Mixed SD couplings are examined: e.g. ~10 GeV mass WIMPs with an = +/- ap are found to be consistent with all experiments. In short, there are surviving regions at low mass for both SI and SD interactions; if indirect detection limits are relaxed, some SD proton-only couplings at high masses also survive.Keywords
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