Probing DAMA/LIBRA data in the full parameter space of WIMP effective models of inelastic scattering

Abstract

We discuss the compatibility of the combined annual modulation effect measured by DAMA/LIBRA-phase1 and DAMA/LIBRA-phase2 with an explanation in terms of inelastic scattering events induced by the most general Galilean-invariant effective contact interaction of a Weakly Interacting Massive Particle (WIMP) dark matter particle of spin 0, 1/2 or 1. We take into account all the possible interferences among operators by studying the intersections among the ellipsoidal surfaces of constant signal of DAMA and other experiments in the space of the coupling constants of the effective theory. In our analysis we assume a standard Maxwellian velocity distribution in the Galaxy. We find that, compared to the elastic case, inelastic scattering partially relieves but does not eliminate the existing tension between the DAMA effect and the constraints from the null results of other experiments. Such tension is very large in all the parameter space with the exception of a small region for WIMP mass m χ ≃ 10 GeV and mass splitting δ > ∼ 20 keV, where it is partially, but not completely relieved. In such region the bounds from fluorine targets are evaded in a kinematic way because the minimal WIMP incoming speed required to trigger upscatters off fluorine exceeds the maximal WIMP velocity in the Galaxy, or is very close to it. As a consequence, we also find that the residual tension between DAMA and other results is considerably more sensitive on the astrophysical parameters compared to the elastic case. We find that the configurations with the smallest tension can produce enough yearly modulation in some of the DAMA bins in compliance with the constraints from other experiments, but the ensuing shape of the modulation spectrum is too steep compared to the measured one. For such configurations the recent COSINE-100 bound is evaded in a natural way due to their large expected modulation fractions.

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“…Recently analyses of the inelastic DM candidate with SD coupling have been reported in Refs. [64,65]. They show that also this scenario can be compatible with the DAMA result.…”

Is a WIMP explanation of the DAMA modulation effect still viable?

“…In Ref. [7] we also considered an extension of the present analysis to the case of the most general Galilean-invariant WIMP-nucleon effective contact interaction for a spin 0, 1/2 or 1 WIMP dark matter following the approach introduced in [8] and checked the compatibility of the DAMA effect in an inelastic scattering scenario. In particular in that analysis, we also included all possible interferences among operators and found that in comparison to the elastic case discussed in [8], inelastic scattering partially relieves but does not eliminate the existing tension between the DAMA effect and the constraints from other experiments, when a Maxwellian velocity distribution for WIMPs is considered.…”

Low-mass inelastic dark matter direct detection via the Migdal effect

“…Although inelastic dark matter scattering has been studied in-depth in the context of models to explain the DAMA excess [38,42,[56][57][58], it is in fact a generic feature of some classes of dark matter models. While we will not explore particular inelastic dark matter models for the purpose of this paper, we provide the following as an illustrative example.…”