Proton-philic spin-dependent inelastic dark matter as a viable explanation of DAMA/LIBRA-phase2

초록

We show that the weakly interacting massive particle scenario of proton-philic spin-dependent inelastic dark matter (pSIDM) can still provide a viable explanation of the observed DAMA modulation amplitude in compliance with the constraints from other experiments after the release of the DAMA/LIBRA-phase2 data and including the recent bound from COSINE-100, that uses the same NaI target of DAMA. The pSIDM scenario provided a viable explanation of DAMA/LIBRA-phase1 both for a Maxwellian WIMP velocity distribution and in a halo-independent approach. At variance with DAMA/LIBRA-phase1, for which the modulation amplitudes showed an isolated maximum at low energy, the DAMA/LIBRA-phase2 spectrum is compatible to a monotonically decreasing one. Moreover, due to its lower threshold, it is sensitive to WIMP-iodine interactions at lowWIMP masses. Due to the combination of these two effects pSIDM can now explain the yearly modulation observed by DAMA/LIBRA only when the WIMP velocity distribution departs from a standard Maxwellian. In this case the WIMP mass m(chi) and mass splitting delta fall in the approximate ranges 7 GeV less than or similar to m(chi)less than or similar to 17 GeV and 18 keV less than or similar to delta less than or similar to 29 keV. The recent COSINE-100 bound is naturally evaded in the pSDIM scenario due to its large expected modulation fractions.