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700
Unification of dark matter and dark energy: The inhomogeneous Chaplygin gas, Phys
 Lett. B535
"... We extend the world model of Kamenshchik et al. to large perturbations by formulating a Zeldovichlike approximation. We sketch how this model unifies dark matter with dark energy in a geometric setting reminiscent of Mtheory. After nearly two decades of reign [1], the Einsteinde Sitter dust model ..."
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We extend the world model of Kamenshchik et al. to large perturbations by formulating a Zeldovichlike approximation. We sketch how this model unifies dark matter with dark energy in a geometric setting reminiscent of Mtheory. After nearly two decades of reign [1], the Einsteinde Sitter dust model has been swept aside by observations of high redshift supernovae [2] which suggest that the Hubble expansion is accelerating. When combined with the Boomerang/Maxima data [3] showing that the location of the first acoustic peak in the power spectrum of the microwave background is consistent with the inflationary prediction Ω = 1, the evidence for a net equation of state of the cosmic fluid lying in the range −1 ≤ w = P/ρ < −1/3 is compelling. Parametrically, w = PDE/(ρDE + ρDM) = −ΩΛ gives a ratio of unclustered dark energy to clustered dark matter of order 7:3, thereby also resolving the longstanding ΩDM < 1 puzzle [1, 4] implied by peculiar velocity fields. The theoretical implications of these dicoveries are profound. Simply appending a
Topology and the cosmic microwave background
 Phys. Rep
"... Nature abhors an infinity. The limits of general relativity are often signaled by infinities: infinite curvature as in the center of a black hole, the infinite energy of the singular big bang. We might be inclined to add an infinite universe to the list of intolerable infinities. Theories that move ..."
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Nature abhors an infinity. The limits of general relativity are often signaled by infinities: infinite curvature as in the center of a black hole, the infinite energy of the singular big bang. We might be inclined to add an infinite universe to the list of intolerable infinities. Theories that move beyond general relativity naturally treat space as finite. In this review we discuss the mathematics of finite spaces and our aspirations
Finite Temperature Field Theory and Phase Transitions, hepph/9901312
"... We review different aspects of field theory at zero and finite temperature, related to the theory of phase transitions. We discuss different renormalization conditions for the effective potential at zero temperature, emphasizing in particular the MS renormalization scheme. Finite temperature field t ..."
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Cited by 23 (0 self)
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We review different aspects of field theory at zero and finite temperature, related to the theory of phase transitions. We discuss different renormalization conditions for the effective potential at zero temperature, emphasizing in particular the MS renormalization scheme. Finite temperature field theory is discussed in the real and imaginary time formalisms, showing their equivalence in simple examples. Bubble nucleation by thermal tunneling, and the subsequent development of the phase transition is described in some detail. Some attention is also devoted to the breakdown of the perturbative expansion and the infrared problem in the finite temperature field theory. Finally the application to baryogenesis at the electroweak phase transition is done in the Standard Model and in the Minimal Supersymmetric Standard Model. In all cases we have translated the condition of not washing out any previously generated baryon asymmetry by upper bounds on the Higgs mass.
Halo models of large scale structure
 Phys. Rep
, 2002
"... We review the formalism and applications of the halobased description of nonlinear gravitational clustering. In this approach, all mass is associated with virialized dark matter halos; models of the number and spatial distribution of the halos, and the distribution of dark matter within each halo, ..."
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We review the formalism and applications of the halobased description of nonlinear gravitational clustering. In this approach, all mass is associated with virialized dark matter halos; models of the number and spatial distribution of the halos, and the distribution of dark matter within each halo, are used to provide estimates of how the statistical properties of large scale density and velocity fields evolve as a result of nonlinear gravitational clustering. We first describe the model, and demonstrate its accuracy by comparing its predictions with exact results from numerical simulations of nonlinear gravitational clustering. We then present several astrophysical applications of the halo model: these include models of the spatial distribution of galaxies, the nonlinear velocity, momentum and pressure fields, descriptions of weak gravitational lensing, and estimates of secondary contributions to temperature fluctuations in the cosmic microwave background.
Sterile neutrino hot, warm, and cold dark matter
 Phys. Rev. D64 (2001) 023501, [astroph/0101524], [SPRIES
"... We calculate the incoherent resonant and nonresonant scattering production of sterile neutrinos in the early universe. We find ranges of sterile neutrino masses, vacuum mixing angles, and initial lepton numbers which allow these species to constitute viable Hot, Warm, and Cold Dark Matter (HDM, WDM ..."
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We calculate the incoherent resonant and nonresonant scattering production of sterile neutrinos in the early universe. We find ranges of sterile neutrino masses, vacuum mixing angles, and initial lepton numbers which allow these species to constitute viable Hot, Warm, and Cold Dark Matter (HDM, WDM, CDM) candidates which meet observational constraints. The constraints considered here include energy loss in core collapse supernovae, energy density limits at big bang nucleosynthesis, and those stemming from sterile neutrino decay: limits from observed cosmic microwave background anisotropies, diffuse extragalactic background radiation, and 6 Li/D overproduction. Our calculations explicitly include matter effects, both effective mixing angle suppression and enhancement (MSW resonance), as well as quantum damping. We for the first time properly include all finite temperature effects, dilution resulting from the annihilation/disappearance of relativistic degrees of freedom, and the scatteringrateenhancing effects of particleantiparticle pairs (muons, tauons, quarks) at high temperature in the early universe. PACS numbers: 95.35.+d,14.60.St,14.60.Pq,98.65.r I.
Gravitino dark matter and cosmological constraints,” JCAP 0609
, 2006
"... Preprint typeset in JHEP style PAPER VERSION hepph/0605306 ..."
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Preprint typeset in JHEP style PAPER VERSION hepph/0605306
Does the universe in fact contain almost no information
 Foundations of Physics Letters 9
, 1996
"... At first sight, an accurate description of the state of the universe appears to require a mindbogglingly large and perhaps even infinite amount of information, even if we restrict our attention to a small subsystem such as a rabbit. In this paper, it is suggested that most of this information is me ..."
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At first sight, an accurate description of the state of the universe appears to require a mindbogglingly large and perhaps even infinite amount of information, even if we restrict our attention to a small subsystem such as a rabbit. In this paper, it is suggested that most of this information is merely apparent, as seen from our subjective viewpoints, and that the algorithmic information content of the universe as a whole is close to zero. It is argued that if the Schrödinger equation is universally valid, then decoherence together with the standard chaotic behavior of certain nonlinear systems will make the universe appear extremely complex to any selfaware subsets that happen to inhabit it now, even if it was in a quite simple state shortly after the big bang. For instance, gravitational instability would amplify the microscopic primordial density fluctuations that are required by the Heisenberg uncertainty principle into quite macroscopic inhomogeneities, forcing the current wavefunction of the universe to contain such Byzantine superpositions as our planet being in many macroscopically different places at once. Since decoherence bars us from experiencing more than one macroscopic reality, we would see seemingly complex constellations of stars etc., even if the initial wavefunction of the universe was perfectly homogeneous and isotropic.
The abundance of KaluzaKlein dark matter with coannihilation, Phys. Rev. D73
, 2006
"... In Universal Extra Dimension models, the lightest KaluzaKlein (KK) particle is generically the first KK excitation of the photon and can be stable, serving as particle dark matter. We calculate the thermal relic abundance of the KK photon for a general mass spectrum of KK excitations including full ..."
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In Universal Extra Dimension models, the lightest KaluzaKlein (KK) particle is generically the first KK excitation of the photon and can be stable, serving as particle dark matter. We calculate the thermal relic abundance of the KK photon for a general mass spectrum of KK excitations including full coannihilation effects with all (level one) KK excitations. We find that including coannihilation can significantly change the relic abundance when the coannihilating particles are within about 20 % of the mass of the KK photon. Matching the relic abundance with cosmological data, we find the mass range of the KK photon is much wider than previously found, up to about 2 TeV if the masses of the strongly interacting level one KK particles are within five percent of the mass of the KK photon. We also find cases where several coannihilation channels compete (constructively and destructively) with one another. The lower bound on the KK photon mass, about 540 GeV when just righthanded KK leptons coannihilate with the KK photon, relaxes upward by several hundred GeV when One of the most important astrophysical challenges is to understand the nature and identity
Sage Foundation
 Story: Immigrant Workers and the Future of the U.S. Labor Movement
"... mechanics and the description of the early universe ..."
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mechanics and the description of the early universe
Implications of SUSY model building
"... We discuss the motivations and implications of models of lowenergy supersymmetry. We present the case for the minimal supersymmetric standard model, which we define to include the minimal particle content and soft supersymmetrybreaking interactions which are universal at the GUT or Planck scale. T ..."
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We discuss the motivations and implications of models of lowenergy supersymmetry. We present the case for the minimal supersymmetric standard model, which we define to include the minimal particle content and soft supersymmetrybreaking interactions which are universal at the GUT or Planck scale. This model is in agreement with all present experimental results, and yet depends on only a few unknown parameters and therefore maintains considerable predictive power. From the theoretical side, it arises naturally in the context of supergravity models. We discuss radiative electroweak symmetry breaking and the superpartner spectrum in this scenario, with some added emphasis on regions of parameter space leading to unusual or interesting experimental signals at future colliders. We then examine how these results may be affected by various modifications and extensions of the minimal model, including GUT effects, extended gauge, Higgs, and matter sectors, nonuniversal supersymmetry breaking, nonconservation of Rparity, and dynamical supersymmetry breaking at low energies. Heisenberg fellow