DAMA/LIBRA-phase2 in WIMP effective models

Abstract

The DAMA/LIBRA collaboration has recently released updated results from their search for the annual modulation signal expected from Dark Matter (DM) scattering in their NaI detectors. We have fitted the updated DAMA result for the modulation amplitudes in terms of a Weakly Interacting Massive Particle (WIMP) signal, parameterizing the interaction with nuclei in terms of the most general effective Lagrangian for a WIMP particle spin up to 1/2, systematically assuming dominance of one of the 14 possible interaction terms, and assuming for the WIMP velocity distribution a standard Maxwellian. We find that most of the couplings of the non-relativistic effective Hamiltonian can provide a better fit compared to the standard Spin Independent interaction case, and with a reduced fine-tuning of the three parameters (WIMP mass, WIMP-nucleon effective cross-section and ratio between the WIMP-neutron and the WIMP-proton couplings). Moreover, effective models for which the cross section depends explicitly on the WIMP incoming velocity can provide a better fit of the DAMA data at large values of m χ compared to the standard velocity-independent crosssection due to a different phase of the modulation amplitudes. All the best fit solutions are in tension with exclusion plots of both XENON1T and PICO60.

Analysis of backgrounds for the ANAIS-112 dark matter experiment

“…The DAMA/LIBRA experiment, running first 100 kg (DAMA/NaI phase) and later 250 kg (DAMA/LIBRA phases 1 and 2) of NaI(Tl) detectors at the Gran Sasso Underground Laboratory, has found a significant (12.9σ) rate modulation over 20 years in the 2-6 keV ee 1 energy region showing the expected features for a galactic halo WIMPs signal [1,2]. Other experiments searching for dark matter with other targets or techniques have not found any signal of dark matter [3,4,5,6,7,8,9,10,11,12] and have been ruling out the most plausible compatibility dark matter scenarios [13], although comparison among results obtained with different target nuclei is model dependent. The identification of the annual modulation in the detection rate is a signature of the scattering of the dark matter particles with the detector nuclei [14]; other experiments using different targets have not presented evidence of this effect [15,16,17], although some hints were reported [18].…”

Comparison between DAMA/LIBRA and COSINE-100 in the light of quenching factors

“…For the DAMA/LIBRA-phase1 data, the isospin conserving SI scattering with DAMA QF values provided a good fit for WIMPs [33]. On the other hand, the observed DAMA/LIBRA-phase2 modulation data does not provide a good fit to the expectations for this model [37][38][39]. Switching to the new QF values for both the phase1 and phase2 data does not improve the phase2 data's agreement with the model, as shown in Fig.…”

“…While the DAMA/LIBRA-phase1 results used a 2 keVee (electron equivalent energy) energy threshold, the recent phase2 result has a lower threshold of 1 keVee [11]. The new low-threshold energy signal has a significantly worse goodness-of-fit for the canonical SI scattering scenario [37][38][39], suggesting that an isospin-violating model in which the WIMP-proton coupling is different from the WIMP-neutron coupling, or a spin-dependent (SD) interaction model are better suited for WIMP dark matter interpretations of the signal.…”

Paleo-detectors: Searching for dark matter with ancient minerals

“…Such isotopes are quite rare in nature, for example, 17 O only makes up 0.04 % of natural oxygen. The most promising isotopes which are relatively common in nature appear to be 25 Mg, comprising 10 % of natural magnesium, and 29 Si, comprising 5 % of natural silicon. Another isotope with large nuclear spin is 91 Zr, comprising 11% of natural zirconium, however, zirconium is relatively rare in nature.…”