5,339 research outputs found
Towards a precise measurement of the top quark Yukawa coupling at the ILC
A precise measurement of the top quark Yukawa coupling is of great
importance, since it may shed light on the mechanism of EWSB. We study the
prospects of such measurement during the first phase of the ILC at sqrt(s)=500
GeV, focusing in particular on recent theoretical developments as well as the
potential benefits of beam polarization. It is shown that both yield
improvements that could possibly lead to a measurement competitive with the
LHC.Comment: Invited talk at 2005 International Linear Collider Physics and
Detector Workshop and Second ILC Accelerator Workshop, Snowmass, CO
(Snowmass05) 3 pages, LaTeX, 3 eps figure
Shedding light on the asymmetry: the photon handle
We investigate a charge asymmetry in production at the LHC
that provides complementary information to the measured asymmetries in production. We estimate the experimental uncertainty in its measurement at
the LHC with 8 and 14 TeV. For new physics models that simultaneously reproduce
the asymmetry excess in at the Tevatron and the SM-like asymmetry at
the LHC, the measurement in at the LHC could exhibit
significant deviations with respect to the SM prediction.Comment: LaTeX 15 page
Asymmetries in top quark pair production at hadron colliders
We review the asymmetries in top quark pair production at the Tevatron and
the LHC. We summarize the experimental measurements and the interpretations of
a possible excess in terms of new physics. We also review other top quark
properties-emphasizing effects related to the asymmetries-as well as
other collider signals.Comment: RevTeX 40 pages. Final version to be published in Reviews of Modern
Physics, with several addition
Micro-Jet Test Facility for Aerospace Propulsion Engineering Education
This paper describes the methodology that has been developed and implemented at the School ofAeronautics (ETSIA) of the Universidad Politecnica de Madrid (UPM) to familiarize aerospaceengineering students with the operation of real complex jet engine systems. This methodology has atwo-pronged approach: students carry out preparatory work by using, first, a gas turbineperformance prediction numerical code; then they validate their assumptions and results on anexperimental test rig. When looking at the educational aspects, we have taken care that, apart frombeing sufficiently robust and flexible, the experimental set-up is similar to real jet engine rigs, so thestudents are not constrained to exploring a much too limited parametric space. Also, because afacility like this is usually subject to extensive and somewhat rugged use, we have focused on a lowcost design
Measuring the Sustainability of Cities: A Survey-Based Analysis of the Use of Local Indicators
We analyze 17 studies of the use of sustainable development indicators (SDI) in an urban setting. The analysis reveals a lack of consensus not only on the conceptual framework and the approach favored, but also on the selection and optimal number of indicators. First, by performing different classifications and categorizations of SDI we identify problems inherent in territorial practices that use SDI. Second, we argue that the lack of consensus in several steps of the creation of SDI stems notably from the ambiguity in the definitions of sustainable development, objectives for the use of such indicators, the selection method and the accessibility of qualitative and quantitative data. Third, we propose a selection strategy for SDI through which we demonstrate the need to adopt a parsimonious list of SDI covering the sustainable development components and their constituent categories as broadly as possible while minimizing the number of indicators retained. Nous analysons 17 études traitant de l’utilisation d’indicateurs de développement durable (IDD) en milieu urbain pour différents pays, provinces ou états occidentaux. 188 IDD différents sont recensés dans ces études dont 135 (72 %) ne sont utilisés qu’une ou deux fois. L’analyse de ces études révèle ainsi un faible consensus non seulement au niveau du cadre conceptuel ou de l’approche préconisée, mais aussi en ce qui concerne la sélection et le nombre d’indicateurs optimal. Premièrement, différents classements et catégorisations des IDD recensés nous permettent d’observer et d’identifier les problèmes inhérents aux pratiques territoriales ayant recours aux IDD. Deuxièmement, nous argumentons que l’absence de consensus à plusieurs étapes de la création des IDD émergent entre autres de l’ambiguïté occasionnée par la définition du développement durable, des objectifs visées par l’utilisation de tels indicateurs, de la méthode de sélection préconisée et de l’accessibilité des données qualitatives et quantitatives en cette matière. Troisièmement, nous proposons une stratégie de sélection des IDD (que nous appelons SuBSeleC) où nous démontrons la nécessité d’adoption d’une liste parcimonieuse d’IDD couvrant le plus largement possible les volets du développement durable et des catégories qui les composent tout en minimisant le nombre d’indicateurs retenus. Le résultat est une liste concise et moins redondante d’indicateurs moins sectoriels et plus intégrateurs ayant l’avantage d’englober les dimensions intégrées du développement durable.Cities, Indicators, Sustainable Development, Environment, Local Governance., Villes, indicateurs, développement durable, environnement, gouvernance locale.
Spontaneous electro-weak symmetry breaking and cold dark matter
In the standard model, the weak gauge bosons and fermions obtain mass after
spontaneous electro-weak symmetry breaking, which is realized through one
fundamental scalar field, namely Higgs field. In this paper we study the
simplest scalar cold dark matter model in which the scalar cold dark matter
also obtains mass through interaction with the weak-doublet Higgs field, the
same way as those of weak gauge bosons and fermions. Our study shows that the
correct cold dark matter relic abundance within uncertainty () and experimentally allowed Higgs boson mass
( GeV) constrain the scalar dark matter mass within GeV. This result is in excellent agreement with that of W. de
Boer et.al. ( GeV). Such kind of dark matter annihilation can
account for the observed gamma rays excess () at EGRET for energies
above 1 GeV in comparison with the expectations from conventional Galactic
models. We also investigate other phenomenological consequences of this model.
For example, the Higgs boson decays dominantly into scalar cold dark matter if
its mass lies within GeV.Comment: 4 Revtex4 pages, refs adde
Paratuberculosis control: a review with a focus on vaccination
Mycobacterium avium subsp. paratuberculosis (MAP) infection causes in ruminants a regional chronic enteritis that is increasingly being recognized as a significant problem affecting animal health, farming and the food industry due to the high prevalence of the disease and to recent research data strengthening the link between the pathogen and human inflammatory bowel disease (IBD). Control of the infection through hygiene-management measures and test and culling of positive animals has to date not produced the expected results and thus a new focus on vaccination against this pathogen is necessary. This review summarizes all vaccination studies of cattle, sheep or goats reporting production, epidemiological or pathogenetic effects of vaccination published before January 2010 and that provide data amenable to statistical analyses. The meta analysis run on the selected data, allowed us to conclude that most studies included in this review reported that vaccination against MAP is a valuable tool in reducing microbial contamination risks of this pathogen and reducing or delaying production losses and pathogenetic effects but also that it did not fully prevent infection. However, the majority of MAP vaccines were very similar and rudimentary and thus there is room for improvement in vaccine types and formulations
Improved Measurement of ttZ Couplings at the LHC
We consider QCD tt~Z production at the LHC with Z->\bar\nu\nu and
all-hadronic tt~ decays, i.e. pp -> p_T(miss)bb~+4 jets, as a tool to measure
ttZ couplings. This channel has a significantly larger cross section than those
where the Z boson decays leptonically. However, tt~, bb~+4 jet, tt~j and tt~jj
production give rise to potentially large backgrounds. We show that these
processes can be suppressed to an acceptable level with suitable cuts, and find
that adding the p_T(miss)bb~+4 jet channel to the final states used in previous
ttZ couplings analyses will improve the sensitivity by 10-60%. We also discuss
how the measurement of the ttZ couplings may constrain Little Higgs models.Comment: revtex4, 16 pages, 4 figures, 1 tabl
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