Cosmological observations have precisely measured the amount of cold dark matter (CDM) in the Universe. The best fit value corresponds to around 23% of the Universe being composed of CDM. Nothing in the Standard Model (SM) is able to account for this cold dark matter. This provides unambiguous evidence for physics beyond the SM. From particle physics, the hierarchy between the electroweak and Planck scales within the SM provides motivation to consider new physics beyond the SM. In this thesis, I investigated the origin of CDM, analyzed various prospects for indirect detection, and studied its collider implications.We focused on two such models: the Left Right Twin Higgs (LRTH) model and the Inert Doublet model (IDM). Both of these models contain a neutral scalar that is stable and a good CDM candidate. We performed a CDM analysis, and identified regions of parameter space that can account for all of the CDM in the Universe.CDM can become trapped around massive objects such as the Sun, Earth, and galactic center. Over time, these CDM particles can annihilate to produce neutrinos and photons. Within the IDM framework, we analyzed the neutrino signal from the Sun and Earth and the photon signal from the galactic center.Due to the nature of new particles within the IDM, there are implications for signals at high energy colliders, such as the Large Hadron Collider (LHC). These particles are produced and can subsequently decay to CDM, jets, and leptons. Within the framework of the IDM, we performed a dilepton signal analysis at the LHC.There exists a synergy between particle physics and cosmology. The study of the interplay between these two fields could provide valuable insights and bring a better understanding of Nature within our grasp. It is an exciting time for physics.

This report is the product of nearly 800 days of sweat, tears, pills, doubts, fears, public transportation, and staring at blank pages. Though, realistically, it’s probably closer to 12 years. It shall document the creation (or maiming) of a television pilot titled Into the Dark – along with the rise and fall of a naïve hope, the death of inspiration, and the birth of an important understanding. There will probably be something in here about the creative process too. / text

The Dark Matter Experiment with Liquid Argon Using Pulse Shape Discrim- ination (DEAP) is a dark matter experiment based in the SNOLAB facility in Sudbury, Ontario. Its aim is to detect WIMPs, Weakly Interacting Massive Par- ticles, that may make up the missing component of the matter in our universe by the scintillation of liquid argon from nuclear recoils. A 7 kg prototype, DEAP-1, is currently in operation with work underway to scale up to a 1 tonne detector, DEAP-3600, by 2012. For DEAP-3600 to be a competitive dark matter search, a limit of 0.2 fiducial surface alpha events is required in the energy region of interest for three years of run time, or 150 total surface events. Of particular concern to the DEAP experiment is 222Rn and its daughter prod- ucts, as the alpha decays of these isotopes may create events in the detector that mimic a WIMP signature. The first half of this thesis concerns the testing and suc- cessful use of an activated carbon trap to eliminate 222Rn from the argon gas source in DEAP-1. The Carbo-Act F2/F3 grain activated carbon brand was tested as a potential ultra-low activity candidate for a DEAP-3600 filtration system and was found to have an upper limit for its 222Rn emanation rate of 284 atoms/day/kg. A temperature swing system is proposed. If operated at 110 K, an upper limit of five atoms of 222Rn can be expected to enter the detector from the trap. An indirect relationship between the number of low energy nuclear recoil events in the DEAP WIMP region of interest and the number of radon alpha decays was found. The ratio between the low energy events in the WIMP region of interest and the high energy alphas was found to be 0.18 ± 0.03 in the detector. From this, the upper limit of the contribution from the proposed radon trap to the WIMP background in DEAP-3600 will be be ten events for three years of run time, which is within acceptable limits. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2011-01-10 10:27:19.303

No description available.

Yeung, Shek = 暗能量和暗物質模型課題 / 楊碩. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 88-91). / Abstracts in English and Chinese. / Yeung, Shek = An neng liang he an wu zhi mo xing ke ti / Yang Shuo. / Chapter 1 --- Overview of Cosmology --- p.1 / Chapter 1.1 --- The Friedmann-Robertson-Walker Metric and the Friedmann Equations --- p.1 / Chapter 1.2 --- The Hubble constant and the Expansion of the Universe --- p.3 / Chapter 1.3 --- The Energy Contents in the Universe --- p.4 / Chapter 1.4 --- Cosmological Observations --- p.8 / Chapter 2 --- Review of CMB Physics --- p.13 / Chapter 2.1 --- The Anisotropy Spectrum --- p.13 / Chapter 2.2 --- The Boltzmann Equations and Einstein Field Equation --- p.15 / Chapter 2.3 --- Initial Conditions --- p.18 / Chapter 2.4 --- Inhomogeneities of Matters --- p.21 / Chapter 2.5 --- Inhomogeneities and Anisotropies of Photons --- p.23 / Chapter 2.5.1 --- Tightly Coupled Limit of the Boltzmann equations --- p.23 / Chapter 2.5.2 --- Diffusion Damping --- p.25 / Chapter 2.5.3 --- Free Streaming --- p.25 / Chapter 2.5.4 --- Cosmological Parameters --- p.26 / Chapter 3 --- Extra Dimension Model with Casimir Effect --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Extra Dimension Model --- p.29 / Chapter 3.3 --- The Casimir Effect --- p.34 / Chapter 3.4 --- Results and Conclusion --- p.40 / Chapter 4 --- Decaying Sterile Neutrino Model --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- The Model --- p.46 / Chapter 4.3 --- Results and Conclusion --- p.61 / Chapter 5 --- Summary of the Thesis --- p.86 / Bibliography --- p.88

The most popular way to achieve accelerated expansion of the universe is by introducing a scalar field in which motion of state varies with time. The accelerated expanded universe was first observed by Type Ia supernovae and future confirmed by the latest of CMB (Cosmic Microwave Background). The reason for the accelerated universe is the existence of dark energy. In this dissertation, we discuss the relationship between dark matter, dark energy, reheating and the standard model, and we find that it is possible for us to unify dark energy, dark matter and a reheating field into one scalar field. There is a very important stage called inflationary, and we find that the residue of the inflationary field, which is also described by a scalar field, can form bubbles in our universe due to the gravity force. We discuss that these bubbles are stable since they are trapped in their potential wells, and the bubbles can be a candidate for dark matter. We also discuss the scalar singlet filed, with the simplest interaction with the Higgs field, and we find that a static, classical droplet can be formed. The physics picture of the droplet is natural, and it is almost the same as the formation of an oil droplet in water. We show that the droplet is absolutely stable. Due to the very weak interaction with the Standard Model particles, the droplet becomes a very promising candidate for dark matter.

Using data from the Next Generation Virgo Cluster Survey and high-resolution simulations of Virgo cluster-like halos, we determine the stellar-to-halo mass relation (SHMR) for subhalos, using the technique of abundance matching. The subhalo SHMR differs markedly from its field galaxy counterpart, regardless of how the subhalo mass is defined (mass at z = 0, mass at infall, or maximum mass while in the field). The slope of the relation at low mass (M⋆<10^10 Msun) is in all cases steeper than the same for the field. We find conflicting indicators of whether this difference in slope indicates an increasing or decreasing dark-to-stellar ratio; further modelling is required to reach a definitive conclusion. We also find evidence for the existence of a measurable age gradient in velocity, such that older subhalos have lower velocities than their younger peers. This opens the possibility that good quality redshifts of the lower mass galaxies of the Virgo cluster might provide additional constraints on the SHMR at high redshift and its evolution. Finally, we investigate the degree to which mergers, particularly major mergers, cause mixing of old and new material in halos, which has implications for the robustness of any implied radial age gradient. We find only a slight increase in mixing for major mergers over minor mergers, and little evidence for any large amount of mixing being induced by mergers of any ratio.

The most popular way to achieve accelerated expansion of the universe is by introducing a scalar field in which motion of state varies with time. The accelerated expanded universe was first observed by Type Ia supernovae and future confirmed by the latest of CMB (Cosmic Microwave Background). The reason for the accelerated universe is the existence of dark energy. In this dissertation, we discuss the relationship between dark matter, dark energy, reheating and the standard model, and we find that it is possible for us to unify dark energy, dark matter and a reheating field into one scalar field. There is a very important stage called inflationary, and we find that the residue of the inflationary field, which is also described by a scalar field, can form bubbles in our universe due to the gravity force. We discuss that these bubbles are stable since they are trapped in their potential wells, and the bubbles can be a candidate for dark matter. We also discuss the scalar singlet filed, with the simplest interaction with the Higgs field, and we find that a static, classical droplet can be formed. The physics picture of the droplet is natural, and it is almost the same as the formation of an oil droplet in water. We show that the droplet is absolutely stable. Due to the very weak interaction with the Standard Model particles, the droplet becomes a very promising candidate for dark matter.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, December 2003. / Includes bibliographical references. Also available on the Internet.

Using data from the Next Generation Virgo Cluster Survey and high-resolution simulations of Virgo cluster-like halos, we determine the stellar-to-halo mass relation (SHMR) for subhalos, using the technique of abundance matching. The subhalo SHMR differs markedly from its field galaxy counterpart, regardless of how the subhalo mass is defined (mass at z = 0, mass at infall, or maximum mass while in the field). The slope of the relation at low mass (M⋆<10^10 Msun) is in all cases steeper than the same for the field. We find conflicting indicators of whether this difference in slope indicates an increasing or decreasing dark-to-stellar ratio; further modelling is required to reach a definitive conclusion. We also find evidence for the existence of a measurable age gradient in velocity, such that older subhalos have lower velocities than their younger peers. This opens the possibility that good quality redshifts of the lower mass galaxies of the Virgo cluster might provide additional constraints on the SHMR at high redshift and its evolution. Finally, we investigate the degree to which mergers, particularly major mergers, cause mixing of old and new material in halos, which has implications for the robustness of any implied radial age gradient. We find only a slight increase in mixing for major mergers over minor mergers, and little evidence for any large amount of mixing being induced by mergers of any ratio.