Previous work has argued that, in the framework of plasma dark matter models, the DAMA annual modulation signal can be consistently explained with electron recoils. In the specific case of mirror dark matter, that explanation requires an effective low velocity cutoff, $v_c \gtrsim 30,000$ km/s, for the halo mirror electron distribution at the detector. We show here that this cutoff can result from collisional shielding of the detector from the halo wind due to Earth-bound dark matter. We also show that shielding effects can reconcile the kinetic mixing parameter value inferred from direct detection experiments with the value favoured from small scale structure considerations, $ε\approx 2 \times 10^{-10}$.
Plasma dark matter, which arises in dissipative dark matter models, can give rise to large annual modulation signals from keV electron recoils. Previous work has argued that the DAMA annual modulation signal could have an explanation within such a scenario. However, detailed predictions are difficult due to the inherent complexities involved in modelling the halo plasma interactions with Earth-bound dark matter. Here, we consider a simple phenomenological model for the dark matter velocity function relevant for direct detection experiments, and compare the resulting electron scattering rate wi…
Previous work has argued that the DAMA annual modulation signal might be due to electron recoils in plasma dark matter models. A specific model assuming mirror dark matter and featuring collisional shielding of a detector due to Earth-bound dark matter was put forward by this author [arXiv:1806.04293]. That explanation predicted a low energy electron recoil signal in the XENON1T experiment. In light of the excess of electron recoils observed in XENON1T, we re-examine that model's predictions for both DAMA and XENON1T.
If dark matter is composed of new fundamental particles, Earth's orbital motion around the Sun may induce an annual modulation in the rate at which these particles interact in a terrestrial detector. The DAMA collaboration has identified at a 12$σ$ confidence level such an annual modulation in their event rate. One previously proposed explanation is `plasma dark matter' (e.g. mirror dark matter) which would have electron recoils in the detector from interactions via kinetic mixing. We perform a chi-squared goodness of fit test of this plasma dark matter model to DAMA/LIBRA modulation amplitude…
The DAMA collaboration reported an annually modulated rate with a phase compatible with a Dark Matter induced signal. We point out that a slowly varying rate can bias or even simulate an annual modulation if data are analyzed in terms of residuals computed by subtracting approximately yearly averages starting from a fixed date, rather than a background continuous in time. In the most extreme case, the amplitude and phase of the annual modulation reported by DAMA could be alternatively interpreted as a decennial growth of the rate. This possibility appears mildly disfavoured by a detailed study…
In a recent paper [arXiv:2002.00459], Buttazzo et al. show how the annually modulated rate of the DAMA experiments can be possibly interpreted as an artefact due to the interplay between a time-dependent background and the method to account for it. In this work, we compare this hypothesis against the sinusoidal dark matter signal as proposed by the DAMA collaboration. We produce in a Bayesian approach a quantitative comparison of how much the experimental observations are in support of each hypothesis. Our conclusions are that the odds against the hypothesis of a time varying background being …
We implement a test of the variability of the per-cycle annual modulation amplitude in the different phases of the DAMA/LIBRA experiment using Bayesian model comparison. Using frequentist methods, a previous study (Kelso et al 2018) had demonstrated that the DAMA amplitudes spanning over the DAMA/NaI and the first phase of the DAMA/LIBRA phases, show a mild preference for time-dependence in multiple energy bins. With that motivation, we first show using Bayesian techniques that the aforementioned data analyzed in Kelso et al, show a moderate preference for exponentially varying amplitudes in t…
DAMA/LIBRA实验，在I.N.F.N.的Gran Sasso国家实验室进行。在意大利，有一个敏感的质量约250公斤的高放射纯NaI（Tl）。它主要致力于利用与模型无关的暗物质年调制特征研究星系晕中的暗物质粒子。目前的DAMA/LIBRA实验和以前的DAMA/NaI实验（第一代实验的受照质量约为100公斤）迄今为止公布的结果相当于在13个年周期内每年受照1.17吨。它们提供了一个独立于模型的证据，证明了在8.9 σ C. L的星系晕中存在DM粒子。所获得的结果的一个简短的总结和未来的前景提到的实验。
Several of the many proposed Dark Matter candidate particles, already investigated with lower exposure and a higher software energy threshold, are further analyzed including the first DAMA/LIBRA--phase2 data release, with an exposure of 1.13 ton $\times$ yr and a lower software energy threshold (1 keV). The cumulative exposure above 2 keV considering also DAMA/NaI and DAMA/LIBRA--phase1 results is now 2.46 ton $\times$ yr. The analysis permits to constraint the parameters' space of the considered candidates restricting their values -- with respect to previous analyses -- thanks to the increase…
The long-standing model-independent annual modulation effect measured by DAMA deep underground at Gran Sasso Laboratory with different experimental configurations is summarized and perspectives will be highlighted. DAMA/LIBRA-phase2 set-up, $\simeq$ 250 kg highly radio-pure NaI(Tl) confirms the evidence of a signal that meets all the requirements of the model independent Dark Matter annual modulation signature at high C.L.; the full exposure is 2.86 ton $\times$ yr over 22 annual cycles. The experiment is currently collecting data in the DAMA/LIBRA-phase2 empowered configuration with an even l…
Effect of the galactic halo modeling on the DAMA/NaI annual modulation result: an extended analysis of the data for WIMPs with a purely spin-independent coupling
The current paradigm for dark matter direct detection is to assume that the dark sector is solely composed of a single particle species. In this short paper, we make the observation that dark matter comprising both a light and a heavy component that modulate out of phase leads to interesting phenomenology in annual modulation experiments. For an illustrative example, we use the recently released DAMA/LIBRA phase-2 results with a lower energy threshold. Immediately after, it was argued that a one-component spin-independent dark matter explanation of the observed annual modulation is strongly di…
The DAMA/LIBRA experiment shows $9.5 σ$ evidence for an annual modulation in the $(1-6)~ {\rm keV}$ energy range, strongly suggesting that the observed modulation has the dark matter origin. However, the conventional interpretation in terms of WIMP-nucleon interaction is excluded by other experiments. We propose an alternative source of modulation in the form of neutrons, which have been liberated from surrounding material. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented long ago to explain the similarity between the dark an…
Experimental observations and theoretical arguments point out that Dark Matter (DM) particles are one of the most prominent component of the Universe. This motivated the pioneer DAMA experiment to investigate the presence of these particles in the galactic halo, by exploiting the model independent signature of the DM annual modulation of the rate and very highly radio-pure apparatus in underground site. In this paper the results obtained by other two annual cycles of DAMA/LIBRA-phase2 are presented and the long-standing model-independent annual modulation effect measured by DAMA deep undergrou…
The relative sensitivity of different direct detection experiments depends sensitively on the astrophysical distribution and particle physics nature of dark matter, prohibiting a model-independent comparison. The situation changes fundamentally if two experiments employ the same target material. We show that in this case one can compare measurements of an annual modulation and exclusion bounds on the total rate while making no assumptions on astrophysics and no (or only very general) assumptions on particle physics. In particular, we show that the dark matter interpretation of the DAMA/LIBRA s…
DAMA/LIBRA and dark matter: decisive tension or contrived cancellation
ARC Centre of Excellence for Dark Matter Particle Physics（暗物质粒子物理卓越研究中心）；University of Adelaide（阿德莱德大学）；Weber State University（韦伯州立大学）；Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）；Karlsruhe Institute of Technology (KIT)（卡尔斯鲁厄理工学院）；University of Oslo（奥斯陆大学）；University of Cincinnati（辛辛那提大学）；Queen’s University（女王大学）；Arthur B. McDonald Canadian Astroparticle Physics Research Institute（亚瑟·B·麦克唐纳加拿大亚原子物理研究所）；Perimeter Institute for Theoretical Physics（理论物理珀蒂默研究所）
We show that models of strongly interacting (SIMP) dark matter built to reproduce the DAMA signal actually cannot account for its time dependence. We discuss the constraints on this type of models coming from direct detection experiments and study the propagation of thermalised dark matter particles in the ground for the allowed values of the parameters. We consider a simple 1D diffusion and a more detailed 3D diffusion. In both cases the predicted signal has either the wrong phase of the annual modulation or a much larger amplitude of the diurnal modulation.
