1,720,963 research outputs found
Direct versus indirect detection in mSUGRA with self-consistent halo models
No full textWe perform a detailed analysis of the detection prospects of neutralino dark matter in the mSUGRA framework. We focus on models with a thermal relic density, estimated with high accuracy using the DarkSUSY package, in the range favoured by current precision cosmological measurements. Direct and indirect detection rates are computed implementing two models for the dark matter halo, tracing opposite regimes for the phase of baryon infall, with fully consistent density profiles and velocity distribution functions. This has allowed, for the first time, a fully consistent comparison between direct and indirect detection prospects. We discuss all relevant regimes in the mSUGRA parameter space, underlining relevant effects, and providing the basis for extending the discussion to alternative frameworks. In general, we find that direct detection and searches for antideuterons in the cosmic rays seems to be the most promising ways to search for neutralinos in these scenarios
Accurate relic densities with neutralino, chargino and sfermion coannihilations in mSUGRA
No full textNeutralinos arise as natural dark matter candidates in many supersymmetric extensions of the Standard Model. We present a novel calculation of the neutralino relic abundance in which we include all so-called coannihilation processes between neutralinos, charginos and sfermions, and, at the same time, we apply the state of the art technique to trace the freeze-out of a species in the early Universe. As a first application, we discuss here results valid in the mSUGRA framework; we describe general trends as well as performing a detailed study of the neutralino relic densities in the mSUGRA parameter space. The emerging picture is fair agreement with previous analyses in the same framework, however we have the power to discuss it in much more detail than previously done. For example, we find that the cosmological bound on the neutralino mass is pushed up to similar to 565 GeV in the stau coannihilation region and to similar to 1500 GeV in the chargino coannihilation region
Constraining pre Big-Bang-Nucleosynthesis Expansion using Cosmic Antiprotons
No full textA host of dark energy models and non–standard cosmologies predict an enhanced Hubble rate in
the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic
microwave background and general relativity tests, may nevertheless lead to enhancements of the
Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre–
BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal
relic, by combining the dark matter relic density bound with constraints coming from the production
of cosmic–ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be
sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark
matter masses lighter than 100 GeV, the bound on the Hubble–rate enhancement ranges from a
factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of
500 GeV the bound falls in the range 50–500. Uncertainties in the derivation of the bounds and
situations where the bounds become looser are discussed. We finally discuss how these limits apply
to some specific realizations of non–standard cosmologies: a scalar–tensor gravity model, kination
models and a Randall–Sundrum D–brane model
Accurate (In)direct detection rates for neutralinos
No full textNeutralinos arise as natural cold dark matter candidates in many supersymmetric extensions of the Standard Model of particle physics. If Galactic neutralinos exist, they could in principle be detected by both direct and indirect detection techniques. We use the DarkSUSY package to make very accurate calculations of the expected detection rates for a wide scan of parameter values. We compare the calculations with the sensitivity of current and future detectors, and conclude that some of the models are above the sensitivity limits. Comments are also made on the mutual dependence between the halo profile and the detection rates
Relic density calculations in mSUGRA including all coannihilations
No full textWe have made a very accurate calculation of the relic density of neutralino dark matter in the minimal supergravity framework. This calculation includes all so-called coannihilations and it uses the DarkSUSY package. In agreement with earlier analyses, we find that coannihilations have a huge effect on the density and this extends the interval of neutralino masses which are cosmologically favoured. We quantify the effect of coannihilations and the neutralino mass bounds. (C) 2005 Elsevier B.V. All rights reserved
DarkSUSY 4.00 neutralino dark matter made easy
No full textWe introduce a new release of the DARKSUSY software. DARKSUSY is a program library for neutralino dark matter signals and neutralino relic density in the minimal supersymmetric standard model. Here, we highlight the improvements and the new features in release 4.00. (C) 2005 Elsevier B.V. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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