Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. We develop a model-independent method for determining the mass $m_χ$ of the WIMP by using data (i.e., measured recoil energies) of direct detection experiments. Our method is independent of the as yet unknown WIMP density near the Earth, of the form of the WIMP velocity distribution, as well as of the WIMP-nucleus cross section. However, it requires positive signals from at least two detectors with different target nuclei. In a background-free environment, $m_χ\sim 50$ GeV could in principle be determined with an error of $\sim 35%$ with only $2 \times 50$ events; in practice upper and lower limits on the recoil energy of signal events, imposed to reduce backgrounds, can increase the error. The method also loses precision if $m_χ$ significantly exceeds the mass of the heaviest target nucleus used.
We argue that WIMP dark matter can annihilate via long-lived "WIMPonium" bound states in reasonable particle physics models of dark matter (DM). WIMPonium bound states can occur at or near threshold leading to substantial enhancements in the DM annihilation rate, closely related to the Sommerfeld effect. Large "boost factor" amplifications in the annihilation rate can thus occur without large density enhancements, possibly preferring colder less dense objects such as dwarf galaxies as locations for indirect DM searches. The radiative capture to and transitions among the WIMPonium states generi…
WIMPless dark matter provides a framework in which dark matter particles with a wide range of masses naturally have the correct thermal relic density. We show that WIMPless dark matter with mass around 2-10 GeV can explain the annual modulation observed by the DAMA experiment without violating the constraints of other dark matter searches. This explanation implies distinctive and promising signals for other direct detection experiments, GLAST, and the LHC.
Since neither supersymmetry nor dark matter WIMPs have yet been observed, pessimism about their reality has been growing. Here we discuss a new supersymmetric theory and a new dark matter candidate which are naturally consistent with current experimental results, but which imply a plethora of new phenomena awaiting discovery within the foreseeable future.
We consider experimental signatures of WIMPless dark matter. We focus on models where the WIMPless dark matter candidate is a Majorana fermion, and dark matter scattering is predominantly spin-dependent. These models can be probed by IceCube/DeepCore, which can potentially find $3σ$ evidence with ~ 5 years of data.
The halo independent comparison of direct dark matter detection data eliminates the need to make any assumption on the uncertain local dark matter distribution and is complementary to the usual data comparison which required assuming a dark halo model for our galaxy. The method, initially proposed for WIMPs with spin-independent contact interactions, has been generalized to any other interaction and applied to recent data on "Light WIMPs".
WIMPless dark matter offers an attractive framework in which dark matter can be very light. We investigate the implications of such scenarios on invisible decays of bottomonium states for dark matter with a mass less than around $5 {\rm GeV}$. We relate these decays to measurements of nucleon-dark matter elastic scattering. We also investigate the effect that a coupling to $s$ quarks has on flavor changing $b\to s$ processes involving missing energy.
I discuss the construction of Simplified Models for Dark Matter searches at the LHC. After reviewing the phylosophy and some simple example, I turn the attention to the aspect of the theoretical consistency of these models.
After a brief introduction to dark matter in general and to WIMPs as candidates, we review recent results of direct dark matter searches. We concentrate on older and more recent hints pointing to light WIMP's with mass below 10 GeV.
We present a halo-independent determination of the unmodulated signal corresponding to the DAMA modulation if interpreted as due to dark matter weakly interacting massive particles (WIMPs). First we show how a modulated signal gives information on the WIMP velocity distribution function in the Galactic rest frame, from which the unmodulated signal descends. Then we perform a mathematically-sound profile likelihood analysis in which we profile the likelihood over a continuum of nuisance parameters (namely, the WIMP velocity distribution). As a first application of the method, which is very gene…
The observed density of dark matter is of the magnitude expected for a thermal relic weakly-interacting massive particle (WIMP). In addition, the observed baryon density is within an order of magnitude of the dark matter density. This suggests that the baryon density is physically related to a typical thermal relic WIMP dark matter density. We present a model which simultaneously generates thermal relic WIMP-like densities for both baryons and dark matter by modifying a large initial baryon asymmetry. Production of unstable scalars carrying baryon number at the LHC would be a clear signature o…
Even if new physics beyond the Standard Model (SM) indeed exists, the energy scale of new physics might be beyond the reach at the Large Hadron Collider (LHC) and the LHC could find only the Higgs boson but nothing else. This is the so-called "nightmare scenario". On the other hand, the existence of the dark matter has been established from various observations. One of the promising candidates for thermal relic dark matter is a stable and electric charge-neutral Weakly Interacting Massive Particle (WIMP) with the mass below the TeV scale. In the nightmare scenario, we introduce a WIMP dark mat…
A weakly interacting massive particle (WIMP) is a leading candidate of the dark matter. The WIMP dark matter abundance is determined by the freeze-out mechanism. Once we know the property of the WIMP particle such as the mass and interaction, we can predict the dark matter abundance. There are, however, several uncertainties in the estimation of the WIMP dark matter abundance. In this work, we focus on the effect from Standard Model thermodynamics. We revisit the estimation of the WIMP dark matter abundance and its uncertainty due to the equation of state (EOS) in the Standard Model. We adopt …
We study under which conditions a scalar particle is a viable WIMP Dark Matter candidate with Higgs and dilaton interactions. The theory is a composite Higgs model with top partial compositeness where both the Higgs and the Dark Matter candidate arise as pseudo Goldstone boson of the coset SO(6)/SO(5) from a new physics sector. We highlight the role of the dilaton in direct and indirect searches. We find that a Dark Matter particle with a mass around 200-400 GeV and a relatively light dilaton are a fair prediction of the model.
Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. For understanding the nature of WIMPs and identifying them among new particles produced at colliders (hopefully in the near future), determinations of their mass and couplings on nucleons from direct Dark Matter detection experiments are essential. Based on our model-independent method for determining the WIMP mass from experimental data, I present a way to also estimate the spin-independent (SI) WIMP-nucleon coupling by using measured recoil energies directly. This method is independent of the velo…
We point out a potential common origin of the recently observed 750 GeV diphoton resonance and a Weakly Interacting Massive Particle (WIMP) candidate. In a dark QCD sector with an unbroken dark G-parity, the diphoton resonance could be a dark G-even pion, while the WIMP could be the lightest dark G-odd pion. Both particles are Standard Model gauge singlets and have the same decay constant. For the dark pion decay constant of around 500 GeV, both the diphoton excess at the LHC and the dark matter thermal abundance can be accommodated in our model. Our model predicts additional dark G-even and d…
Affleck-Dine (AD) mechanism for leptogenesis involves the cosmological evolution of a complex scalar field (AD field) that carries non-zero lepton number. We show how explicit lepton number breaking terms, which involve the AD field needed to implement this scenario combined with fermionic WIMP dark matter, can generate neutrino mass at the one loop level, thus providing a unified framework for solving four major puzzles of the standard model i.e. inflation, baryogenesis, dark matter and neutrino mass. We discuss some phenomenological implications of this model.
Although it is usually thought that a class of weakly interacting massive particle (WIMP) dark matters (DMs), which have the vector coupling with the $Z$ boson, is denied by null results of the direct DM searches, such WIMP DMs are still viable if they are superheavy with the mass of $m_{DM} \gtrsim 10^9$ GeV. In the future, the superheavy WIMP DMs can be searched up to $m_{DM} \simeq 10^{12}$ GeV, which corresponds to the so-called neutrino floor limit. We show that the observed abundance of $Ω_\mathrm{DM}h^2 \simeq 0.1$ for a superheavy WIMP DM can be reproduced by a suitable reheating tempe…
A light fermionic weakly interacting massive particle (WIMP) dark matter is investigated by studying its minimal renormalizable model, where it requires a scalar mediator to have an interaction between the WIMP and standard model particles. We perform a comprehensive likelihood analysis of the model involving the latest but robust constraints and those will be obtained in the near future. In addition, we pay particular attention to properly take the kinematically equilibrium condition into account. It is shown that near-future experiments and observations such as low-mass direct dark matter de…
In the earlier work on the development of a model-independent data analysis method for determining the mass of Weakly Interacting Massive Particles (WIMPs) by using measured recoil energies from direct Dark Matter detection experiments directly, it was assumed that the analyzed data sets are background-free, i.e., all events are WIMP signals. In this article, as a more realistic study, we take into account a fraction of possible residue background events, which pass all discrimination criteria and then mix with other real WIMP-induced events in our data sets. Our simulations show that, for the…
The weakly interacting massive particle (WIMP) often serves as a candidate for the cold dark matter, however when produced non-thermally it could behave like warm dark matter. In this paper we study the properties of the $γ$-ray emission from annihilation of WIMP dark matter in the halo of our own Milky-Way Galaxy with high resolution $N$-body simulations of a Milky-Way like dark matter halo, assuming different nature of WIMPs. Due to the large free-streaming length in the scenario of warm WIMPs, the substructure contend of the dark matter halo is significantly different from that of the cold …
One of the highest priorities in particle physics today is the identification of the constituents of dark matter. This manuscript is a supplement to pedagogical lectures given at the 2021 Les Houches Summer School on Dark Matter. The lectures cover topics related to the direct detection of WIMP dark matter, including the distribution of dark matter, nuclear scattering, backgrounds, planning and designing of experiments and a sampling of planned and ongoing experiments.
We describe the scenario of WIMPless dark matter. In this scenario of gauge-mediated supersymmetry breaking, a dark matter candidate in the hidden sector is found to naturally have approximately the right relic density to explain astronomical dark matter observations, but with a wide range of possible masses.
Sterile neutrinos coupling only to third-generation fermions are attractive dark matter candidates. In an EFT approach we demonstrate that they can generate the observed relic density without violating constraints from direct and indirect detection. Such an EFT represents a gauged third-generation $B-L$ model, as well as third-generation scalar or vector leptoquarks. LHC measurements naturally distinguish the different underlying models.
The class of `Asymmetric Dark Matter' scenarios relies on the existence of a primordial particle/anti-particle asymmetry in the dark sector related to the baryon asymmetry as a way to address the observed similarity between the baryonic and dark matter energy densities today. Focusing on this framework we calculate the evolution of the dark matter relic abundance in the presence of particle/anti-particle oscillations. We show how oscillations re-open the parameter space of asymmetric dark matter models, in particular in the direction of allowing large (WIMP-scale) DM masses. Finally, we constr…
WIMP (Weakly Interacting Massive Particle), FIMP (Feebly interacting Massive Particle) and EWIP (Extremely Weakly Interacting Particle) dark matter are different theoretical frameworks that have been postulated to explain the dark matter. In this paper we examine an intermediate scenario that combines features from these three frameworks. It consists of a weakly interacting particle --a la WIMP-- that does not reach thermal equilibrium in the early Universe --a la FIMP-- and whose relic density is determined by the reheating temperature of the Universe --a la EWIP. As an example, an explicit r…
Serious searches for the weakly interacting massive particle (WIMP) have now begun. In this context, the most important questions that need to be addressed are: "To what extent can we constrain the WIMP models in the future?" and "What will then be the remaining unexplored regions in the WIMP parameter space for each of these models?" In our quest to answer these questions, we classify WIMP in terms of quantum number and study each case adopting minimality as a guiding principle. As a first step, we study one of the simple cases of the minimal composition in the well-tempered fermionic WIMP re…
There exists a widely known conjecture that gravitational effects violate global symmetries. We study the effect of global-symmetry violating higher-dimension operators induced by Planck-scale physics on the properties of WIMP dark matter. Using an effective description, we show that the lifetime of the WIMP dark matter candidate can satisfy cosmological bounds under reasonable assumptions regarding the strength of the dimension-five operators. On the other hand, the indirect WIMP dark matter detection signal is significantly enhanced due to new decay channels.
We explore models in which weakly interacting massive particle (WIMP) dark matter annihilation is directly responsible for baryogenesis, thereby connecting dark matter with baryogenesis. We call this process "WIMPy baryogenesis". The dark matter relic density in these models, as with conventional WIMP models, is obtained with only order one couplings and TeV-scale masses according to the WIMP miracle. Thus, WIMPy baryogenesis models naturally accommodate weak-scale dark matter. Furthermore, an extension of the WIMP miracle simultaneously explains the observed baryon asymmetry and the correct d…
The unidentified emission line at the energy of $\sim$3.5~keV observed in X-rays from galaxy clusters may originate from a process involving a dark matter particle. On the other hand, a weakly interacting massive particle (WIMP) has been an attractive dark matter candidate, due to its well-understood thermal production mechanism and its connection to physics at the TeV scale. In this paper, we pursue the possibility that the 3.5-keV X-ray arises from a late time decay of a WIMP dark matter into another WIMP dark matter, both of which have the mass of $O(100)$~GeV and whose mass splitting is ab…
We discuss phenomenological aspects of models whose scalar sector is extended by an isospin doublet scalar and a complex singlet scalar as an effective theory of supersymmetric models with mixed sneutrinos. In such models, the lighter of the mixed neutral scalars can become a viable dark matter candidate by imposing a U(1) symmetry. We find that the thermal WIMP scenario is consistent with the cosmological dark matter abundance when the mass of the scalar is half of that of the discovered Higgs boson or larger than around 100 GeV. We also point out that, with an additional isospin singlet Majo…
The scotogenic scenario provides an attractive approach to both Dark Matter and neutrino mass generation, in which the same symmetry that stabilises Dark Matter also ensures the radiative seesaw origin of neutrino mass. However the simplest scenario may suffer from inconsistencies arising from the spontaneous breaking of the underlying $\mathbb{Z}_2$ symmetry. Here we show that the singlet-triplet extension of the simplest model naturally avoids this problem due to the presence of scalar triplets neutral under the $\mathbb{Z}_2$ which affect the evolution of the couplings in the scalar sector.…
