5,014 research outputs found

    Monotops at the LHC

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    We explore scenarios where top quarks may be produced singly in association with missing energy, a very distinctive signature, which in analogy with monojets, we dub monotops. We find that monotops can be produced in a variety of modes, typically characterized by baryon number violating or flavor changing neutral interactions. We build a simplified model that encompasses all the possible (tree-level) production mechanisms and study the LHC sensitiveness to a few representative scenarios by considering fully hadronic top decays. We find that constraints on such exotic models can already be set with one inverse femtobarn of integrated luminosity collected at seven TeV.Comment: 4 pages, 3 figures, 1 table; version accepted by PR

    Estimating Discount Functions with Consumption Choices over the Lifecycle

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    Intertemporal preferences are difficult to measure. We estimate time preferences using a structural buffer stock consumption model and the Method of Simulated Moments. The model includes stochastic labor income, liquidity constraints, child and adult dependents, liquid and illiquid assets, revolving credit, retirement, and discount functions that allow short-run and long-run discount rates to differ. Data on retirement wealth accumulation, credit card borrowing, and consumption-income comovement identify the model. Our benchmark estimates imply a 40% short-term annualized discount rate and a 4.3% long-term annualized discount rate. Almost all specifications reject the restriction to a constant discount rate. Our quantitative results are sensitive to assumptions about the return on illiquid assets and the coefficient of relative risk aversion. When we jointly estimate the coefficient of relative risk aversion and the discount function, the short-term discount rate is 15% and the long-term discount rate is 3.8%.

    Self-Control and Saving for Retirement

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    macroeconomics, Self-Control, Saving, Retirement

    No. 06: The Urban Food System of Nairobi, Kenya

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    Nairobi is a city of stark contrasts. Nearly half a million of its three million residents live in abject poverty in some of Africa’s largest slums, yet the Kenyan capital is also an international and regional hub. In East Africa, rapid urbanization is stretching existing food and agriculture systems as growing cities struggle to provide food and nutrition security for their inhabitants. Nairobi is no exception; it is a dynamically growing city and its food supply chains are constantly adapting and responding to changing local conditions. It is also an international city and the extent to which it is food secure is increasingly predicated on food imports from the regional East African Community and other international sources. Informal traditional value chains have a variety of actors and intermediaries that increase transaction costs and create an inefficient post-harvest procurement network, thereby pushing food products out of the reach of those who need them most. The majority of Nairobi’s food purchases are from informal food vendors. The city’s urban poor rely on the informal food sector for several reasons including that it provides food close to where they live and work, credit and barter are often available, small quantities can be purchased, and many items are sold more cheaply than at formal outlets. The leading income-generating activity for women in Nairobi’s poor communities is selling fruit and vegetables

    A psychological approach to providing self-management education for people with type 2 diabetes : the diabetes manual

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    Background: The objectives of this study were twofold (i) to develop the Diabetes Manual, a selfmanagement educational intervention aimed at improving biomedical and psychosocial outcomes (ii) to produce early phase evidence relating to validity and clinical feasibility to inform future research and systematic reviews. Methods: Using the UK Medical Research Council's complex intervention framework, the Diabetes Manual and associated self management interventions were developed through preclinical, and phase I evaluation phases guided by adult-learning and self-efficacy theories, clinical feasibility and health policy protocols. A qualitative needs assessment and an RCT contributed data to the pre-clinical phase. Phase I incorporated intervention development informed by the preclinical phase and a feasibility survey. Results: The pre-clinical and phase I studies resulted in the production in the Diabetes Manual programme for trial evaluation as delivered within routine primary care consultations. Conclusion: This complex intervention shows early feasibility and face validity for both diabetes health professionals and people with diabetes. Randomised trial will determine effectiveness against clinical and psychological outcomes. Further study of some component parts, delivered in alternative combinations, is recommended

    Can Corrective Ad Statements Based on \u3cem\u3eU.S. v. Philip Morris USA Inc.\u3c/em\u3e Affect Consumer Beliefs about Smoking?

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    To comply with the court\u27s ruling in U.S. v. Philip Morris USA Inc., tobacco companies must fund a large advertising campaign to \u27correct\u27 smoking beliefs about which consumers may have been misled as a result of past deceptive practices of tobacco companies. The authors use an ad copy experiment to examine (1) the effects of different versions of corrective ad statements that plaintiff intervenors submitted to the court on multi-item belief measures and (2) the impact of the ad versions and beliefs on general attitudes toward smoking across current adult smokers and nonsmokers. The tested ad versions include a copy-only control condition, a copy-with-graphic-visual condition, and a version with a potentially distracting visual. The results indicate that the corrective statements in advertisements can have a positive effect on antismoking beliefs of focal interest in the case and that the test advertisements affect some beliefs more strongly than others. The authors discuss potential policy implications and limitations and provide suggestions for further research

    Monotop phenomenology at the Large Hadron Collider

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    We investigate new physics scenarios where systems comprised of a single top quark accompanied by missing transverse energy, dubbed monotops, can be produced at the LHC. Following a simplified model approach, we describe all possible monotop production modes via an effective theory and estimate the sensitivity of the LHC, assuming 20 fb−1^{-1} of collisions at a center-of-mass energy of 8 TeV, to the observation of a monotop state. Considering both leptonic and hadronic top quark decays, we show that large fractions of the parameter space are reachable and that new physics particles with masses ranging up to 1.5 TeV can leave hints within the 2012 LHC dataset, assuming moderate new physics coupling strengths.Comment: 17 pages, 12 figures, 3 table

    Discovery potential for T′→tZT' \to tZ in the trilepton channel at the LHC

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    The LHC discovery potential of heavy top partners decaying into a top quark and a ZZ boson is studied in the trilepton channel at s=13\sqrt{s}=13 TeV. The clean multilepton final state allows to strongly reduce the background contaminations and to reconstruct the T′T' mass. We show that a simple cut-and-count analysis probes the parameter space of a simplified model as efficiently as a dedicated multivariate analysis. The trilepton signature finally turns out to be as sensitive in the low T′T' mass region as the complementary channel with a fully hadronic top quark, and more sensitive in the large mass domain. The reinterpretation in terms of the top-ZZ-up anomalous coupling is shown.Comment: 18 pages, 9 figures, 6 tables. Matching published versio

    Chip-to-chip ODDM network with optically enabled equalization

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    We propose and model an optical communication scheme for short distance datacom links based on the distribution of information across a wide comb spectrum. This modulation format, orthogonal delay division multiplexing, allows the multiplexing of data streams from multiple modulators, as well as the deserialization and equalization of the data in the optical domain. A concrete communication system, that allows the transport of 400 Gb/s across a single CWDM channel with a single 80 GHz cutoff lithium niobate on insulator modulator, is modeled under consideration of all noise sources present in the system and its sensitivity to group velocity dispersion is analyzed. Data is deserialized and equalized at the receiver with a 5-tap optical equalizer. This communication architecture may provide a path forward to implement high-baud-rate signaling in short-reach optical links without requiring high-speed ADCs and electronic deserializers at the receiver, thus maintaining the in-package power consumption at manageable levels
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