Dark antiatoms can explain DAMA

We show that the existence of a sub-dominant form of dark matter, made of dark antiatoms of mass and size of the order of 1 TeV and 30 fm respectively, can explain the results of direct detection experiments, with a positive signal in DAMA/NaI and DAMA/LIBRA and no signal in other experiments. The signal comes from the binding of the dark antiatoms to thallium, a dopant in DAMA, and is not present for the constituent atoms of other experiments. The dark antiatoms are made of two particles oppositely charged under a dark U(1) symmetry and can bind to terrestrial atoms because of a kinetic mixing between the photon and the massless dark photon, such that the dark particles acquire an electric millicharge of the order of 0.0005e. This millicharge enables them to bind to high-Z atoms via radiative capture, after they thermalize in terrestrial matter through elastic collisions.Comment: 18 pages, 5 figure

Composite dark matter and direct-search experiments

We reinterpret the results of the direct searches for dark matter in terms of composite dark matter, i.e. dark matter particles that form neutral bound states, generically called dark atoms, either with ordinary particles, or with other dark matter particles. Three different scenarios are investigated: the O-helium scenario, milli- interacting dark matter and dark anti-atoms. In each of them, dark matter interacts sufficiently strongly with terrestrial matter to be stopped in it before reaching underground detectors. As they drift towards the center of the earth by gravity, these thermal dark atoms are radiatively captured by the atoms of the active medium of underground detectors, which causes the emission of photons that produce the signals through their interactions with the electrons of the medium. This provides a way of reinterpreting the results in terms of electron recoils instead of nuclear recoils. The detailed study of the interactions of O-helium with ordinary matter shows that it is not an acceptable candidate for dark matter because of the absence of a repulsion mechanism preventing it from falling into the deep nuclear wells of nuclei. The two other models involve milli-charges and are able to reconcile the most contradictory experiments. We determine, for each model, the regions in the parameter space that reproduce the experiments with positive results in full consistency with the constraints of the experiments with negative results. We also pay attention to the experimental and observational constraints on milli-charges and discuss some typical signatures of the models that could be used to test them.Comment: PhD thesis, defended on September 9, 2015 at the University of Li\`ege, Belgiu

Is dark matter made of mirror matter? Evidence from cosmological data

peer reviewedWe present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly of mirror matter. We consider scalar adiabatic primordial perturbations at linear scales in a flat Universe. The speed of the simulations allows us for the first time to use Markov Chain Monte Carlo analyses to constrain the mirror parameters. A Universe with pure mirror matter can fit very well the observations, equivalently to the case of an admixture with cold dark matter. In both cases, the analyses show a clear indication of the presence of a consistent amount of mirror dark matter, 0.05 < Ω_{mirror} h^2 < 0.12

Development of an urban typology to assess residential environmental performance at the city scale

peer reviewedIn this research, a typology of urban blocks is drawn up for the urban area of Liege. This typology of urban blocks is organized into a set of themes according to various environmental parameters. This paper presents the energy part of this typology on the residential building stock of Liege, which includes four topics: residential buildings energy consumption; transport energy consumption of residents; development potentialities of public transport and development potentialities of energy networks. The proposed typology was elaborated through the use of GIS tools combined with a statistical treatment of several specific criteria at the urban block scale. For each class of this typology, a representative block is selected for further energy simulations in order to model residential energy use related to buildings, transport and energy networks at the city scale. The methodology developed in this paper is adapted to urban, suburban and rural zones. It can thus be adapted and/or reproduced on many other territories in Belgium but also in Europe or even further

Some potential problems of OHe composite dark matter

Among composite-dark-matter scenarios, one of the simplest and most predictive is that of O-helium (OHe) dark atoms, in which a lepton-like doubly charged particle O is bound with a primordial helium nucleus, and is the main constituent of dark matter. This model liberates the physics of dark matter from many unknown features of new physics, and it demands a deep understanding of the details of known nuclear and atomic physics, which are still somewhat unclear in the case of nuclear interacting "atomic" shells. So far the model has relied on the dominance of elastic scattering of OHe with the matter. In view of the uncertainty in our understanding of OHe interaction with nuclei we study the opposite scenario, in which inelastic nuclear reactions dominate the OHe interactions with nuclei. We show that in this case all the OHe atoms bind with extra He nuclei, forming doubly charged O-beryllium ions, which behave like anomalous helium, causing potential problems with overabundance of anomalous isotopes in terrestrial matter.Comment: To appear in Proceedings of the 17th Bled Workshop "What Comes Beyond Standard Models?