The Nature of the Dark Matter (original) (raw)
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Dark Matter Detection in the Light of Recent Experimental Results
International Journal of Modern Physics A, 2004
The existence of dark matter was suggested, using simple gravitational arguments, seventy years ago. Although we are now convinced that most of the mass in the Universe is indeed some nonluminous matter, we still do not know its composition. The problem of the dark matter in the Universe is reviewed here. Particle candidates for dark matter are discussed with particular emphasis on Weakly Interacting Massive Particles (WIMP's). Experiments searching for these relic particles, carried out by many groups around the world, are also reviewed, paying special attention to their direct detection by observing the elastic scattering on target nuclei through nuclear recoils. Finally, we concentrate on the theoretical models predicting WIMP's, and in particular on supersymmetric extensions of the standard model, where the leading candidate for WIMP, the neutralino, is present. There, we compute the cross-section for the direct detection of neutralinos, and compare it with the sensitivi...
Particle candidates for dark matter: A Case for (dominant or subdominant) relic neutralinos
2001
After a short introduction on particle candidates for dark matter within possible extensions of the standard model, we concentrate on Weakly Interacting Massive Particles, and on one of their most interesting physical realizations: the neutralino. We analyze how detectability of relic neutralinos by direct and indirect means is related to their local and cosmological densities; we use simple general arguments to discusss different scenarios where relic neutralinos make up the dominant bulk of dark matter or only a small fraction of it. Our general arguments are further corroborated by specific numerical results. We show to which extent the present experiments of direct searches for WIMPs, when interpreted in terms of relic neutralinos, probe interesting regions of the supersymmetric parameter space. Our analysis is performed in a number of different supersymmetric schemes.
American Scientist
The observational evidence for dark matter on progressively larger cosmic scales is reviewed in a rather pedagogical fashion. Although the emphasis is on dark matter in galaxies and in clusters of galaxies, its cosmological evidence as well as its physical nature are also discussed.
Recent Developments in Supersymmetric Dark Matter
The Identification of Dark Matter - Proceedings of the Third International Workshop, 2001
A brief review is given of some of the recent developments in the theoretical analyses of supersymmetric dark matter. These include the effects of uncertainties in the wimp velocity and wimp density and of the effects of uncertainties in the quark densities of the proton. Also analyzed are the effects of non-universalities in the gaugino sector and their effects on determining the nature of cold dark matter, i.e., if the neutralino is bino like, higgsino like, or wino like. The maximum and the minimum elastic neutralino proton cross sections are discussed and a comparison of the direct and the indirect detection arising from the capture and annihilation of neutralinos in the core of the earth and the sun is given. Some of the other recent developments are summarized.
Dark Matter: Early Considerations
NATO Science Series, 2005
A review of the study of dark matter is given, starting with earliest studies and finishing with the establishment of the standard Cold Dark Matter paradigm in mid 1980-s. Particular attention is given to the collision of the classical and new paradigms concerning the matter content of the Universe. Also the amount of baryonic matter, dark matter and dark energy is discussed using modern estimates.
Astrophysics and Space Science Library, 2011
These lectures are intended to provide a brief pedagogical review of dark matter for the newcomer to the subject. We begin with a discussion of the astrophysical evidence for dark matter. The standard weakly-interacting massive particle (WIMP) scenario-the motivation, particle models, and detection techniques-is then reviewed. We provide a brief sampling of some recent variations to the standard WIMP scenario as well as some alternatives (axions and sterile neutrinos). Exercises are provided for the reader. 1 simple ("squiggly-line") arguments for the existence of dark matter in clusters and galaxies, as well as the arguments for why it is nonbaryonic. The motivation will be to provide insight into the evidence and arguments, rather than to summarize results from the latest state-of-the-art applications of the techniques. Likewise, construction of particle-physics models for dark matter has become a huge industry, accelerated quite recently, in particular, with anomalous cosmic-ray and diffuse-background results . Again, we will not attempt to survey these recent developments and focus instead primarily on the basic arguments for particle dark matter. In particular, there has developed in the theoretical literature over the past twenty years a "standard" weakly-interacting massive particle (WIMP) scenario, in which the dark-matter particle is a particle that arises in extensions (e.g., supersymmetry or universal extra dimensions ) of the standard model that are thought by many particle theorists to provide the best prospects for new-physics discoveries at the Large Hadron Collider (LHC). We therefore describe this basic scenario. More detailed reviews of weakly-interacting massive particles, the main subject of this article, can be found in Refs. .
Astrophysics at Ultra-High Energies - Proceedings of the 15th Course of the International School of Cosmic Ray Astrophysics, 2007
Dark matter has been recognized as an essential part of matter for over 70 years now, and many suggestions have been made, what it could be. Most of these ideas have centered on Cold Dark Matter, particles that are expected in extensions of standard particle physics, such as supersymmetry. Here we explore the concept that dark matter is sterile neutrinos, a concept that is commonly referred to as Warm Dark Matter. Such particles have keV masses, and decay over a very long time, much longer than the Hubble time. In their decay they produce X-ray photons which modify the ionization balance in the early universe, increasing the fraction of molecular Hydrogen, and thus help early star formation. Sterile neutrinos may also help to understand the baryonasymmetry, the pulsar kicks, the early growth of black holes, the minimum mass of dwarf spheroidal galaxies, as well as the shape of dark matter halos. As soon as all these tests have been quantitative in its various parameters, we may focus on the creation mechanism of these particles, and could predict the strength of the sharp X-ray emission line, expected from any large dark matter assembly. A measurement of this X-ray emission line would be definitive proof for the existence of may be called weakly interacting neutrinos, or WINs.
Dark Matter Searches at the LHC
A majority of the matter in the universe doesn't interact strongly with what we think of as "ordinary matter" it is invisible, or "dark". Exhaustive tests have proven the existence of Dark Matter, and Supersymmetry has remained the best contender for its explanation. But in the 43 years since the inception of Supersymmetry, there has not been a single Supersymmetric particle observed. To guide and speed up this search, it is necessary to put limits on what such a particle could be. In this thesis, I perform this limit test on the particle most likely to be Dark Matter the neutralino. By modelling the physics of Supersymmetry with computational tools, signal predictions can be made and tested against data gathered at the Large Hadron Collider. The motivation for considering Supersymmetry is the explanation of this Dark Matter. This paper seeks to provide reassurance that neutralinos as lightest supersymmetric partners are still possible given the measurements done at the LHC.
Neutralinos as dark matter candidates
1994
We review some properties of the neutralino as a candidate for dark matter in the Universe. After presentation of evaluations for the neutralino relic abundance, possibilities for its direct and indirect detections are discussed, with emphasis for measurements at neutrino telescopes.