Multi-Boson Interactions at the LHC

This review covers results on the production of all possible electroweak boson pairs and 2-to-1 vector boson fusion at the CERN Large Hadron Collider (LHC) in proton-proton collisions at a center of mass energy of 7 and 8 TeV. The data were taken between 2010 and 2012. Limits on anomalous triple gauge couplings (aTGCs) then follow. In addition, data on electroweak triple gauge boson production and 2-to-2 vector boson scattering yield limits on anomalous quartic gauge boson couplings (aQGCs). The LHC hosts two general purpose experiments, ATLAS and CMS, which have both reported limits on aTGCs and aQGCs which are herein summarized. The interpretation of these limits in terms of an effective field theory is reviewed, and recommendations are made for testing other types of new physics using multi-gauge boson production.Comment: 53 pages, 48 figures, 4 table

On the "Causality Argument" in Bouncing Cosmologies

We exhibit a situation in which cosmological perturbations of astrophysical relevance propagating through a bounce are affected in a scale-dependent way. Involving only the evolution of a scalar field in a closed universe described by general relativity, the model is consistent with causality. Such a specific counter-example leads to the conclusion that imposing causality is not sufficient to determine the spectrum of perturbations after a bounce provided it is known before. We discuss consequences of this result for string motivated scenarios.Comment: 4 pages, 1 figure, ReVTeX, to appear in Phys. Rev. Let

Global dietary quality, undernutrition and non-communicable disease: a longitudinal modelling study

OBJECTIVES: To determine the relationship between global dietary energy availability and dietary quality, and nutrition-related health outcomes. // DESIGN: A worldwide longitudinal modelling study using country-level data. Data on total dietary energy availability and dietary energy from 10 distinct food groups (as a proxy for dietary quality) were obtained from the FAO Food Balance Sheets database. Indicators of development were abstracted from the World Bank's World Development Indicators database. Data on nutrition and health outcomes were taken from the WHO mortality database and major cross-country analyses. We investigated associations of energy availability from food groups and health and nutrition outcomes in the combined data set using mixed effects models, while adjusting for measures of development. // POPULATION: 124 countries over the period 1980–2009. // MAIN OUTCOME MEASURES: Prevalence of stunting in children under 5 years and mortality rate from ischaemic heart disease (IHD) in adults aged 55+ years. // RESULTS: From 1980 to 2009, global dietary energy availability increased, and rates of child stunting and adult IHD mortality declined. After adjustment for measures of development, increased total dietary energy availability was significantly associated with reduced stunting rates (−0.84% per 100 kcal increase in energy, 95% CI −0.97 to −0.72) and non-significantly associated with increased IHD mortality rates (by 4.2 deaths per 100 000/100 kcal increase, 95% CI −1.85 to 10.2). Further analysis demonstrated that the changing availability of energy from food groups (particularly fruit, vegetables, starchy roots, meat, dairy and sugar) was important in explaining the associations with health outcomes. // CONCLUSIONS: Our study has demonstrated that by combining large, publicly available data sets, important patterns underlying trends in diet-related health can be uncovered. These associations remain even after accounting for measures of development over a 30-year period. Further work and joined-up multisectoral thinking will be required to translate these patterns into policies that can improve nutrition and health outcomes globally

Human search for a target on a textured background is consistent with a stochastic model

Previous work has demonstrated that search for a target in noise is consistent with the predictions of the optimal search strategy, both in the spatial distribution of fixation locations and in the number of fixations observers require to find the target. In this study we describe a challenging visual-search task and compare the number of fixations required by human observers to find the target to predictions made by a stochastic search model. This model relies on a target-visibility map based on human performance in a separate detection task. If the model does not detect the target, then it selects the next saccade by randomly sampling from the distribution of saccades that human observers made. We find that a memoryless stochastic model matches human performance in this task. Furthermore, we find that the similarity in the distribution of fixation locations between human observers and the ideal observer does not replicate: Rather than making the signature doughnut-shaped distribution predicted by the ideal search strategy, the fixations made by observers are best described by a central bias. We conclude that, when searching for a target in noise, humans use an essentially random strategy, which achieves near optimal behavior due to biases in the distributions of saccades we have a tendency to make. The findings reconcile the existence of highly efficient human search performance with recent studies demonstrating clear failures of optimality in single and multiple saccade tasks

Hot Subdwarf Stars Among the Objects Rejected from the PG Catalog: a First Assessment Using GALEX Photometry

The hot subdwarf (sd) stars in the Palomar Green (PG) catalog of ultraviolet excess (UVX) objects play a key role in investigations of the frequency and types of binary companions and the distribution of orbital periods. These are important for establishing whether and by which channels the sd stars arise from interactions in close binary systems. It has been suggested that the list of PG sd stars is biased by the exclusion of many stars in binaries, whose spectra show the Ca II K line in absorption. A total of 1125 objects that were photometrically selected as candidates were ultimately rejected from the final PG catalog using this K-line criterion. We study 88 of these "PG-Rejects" (PGRs), to assess whether there are significant numbers of unrecognized sd stars in binaries among the PGR objects. The presence of a sd should cause a large UVX. We assemble GALEX, Johnson V, and 2MASS photometry and compare the colors of these PGR objects with those of known sd stars, cool single stars, and hot+cool binaries. Sixteen PGRs were detected in both the far- and near- ultraviolet GALEX passbands. Eleven of these, plus the 72 cases with only an upper limit in the far-ultraviolet band, are interpreted as single cool stars. Of the remaining five stars, three are consistent with being sd stars paired with a cool main sequence companion, while two may be single stars or composite systems of another type. We discuss the implications of these findings for the 1125 PGR objects as a whole. (slightly abridged)Comment: 32 pages with 3 figures and 4 tables. Uses AASTEX style files. To be published in The Astronomical Journal (August 2009 issue

Exploring the SO(32) Heterotic String

We give a complete classification of Z_N orbifold compactification of the heterotic SO(32) string theory and show its potential for realistic model building. The appearance of spinor representations of SO(2n) groups is analyzed in detail. We conclude that the heterotic SO(32) string constitutes an interesting part of the string landscape both in view of model constructions and the question of heterotic-type I duality.Comment: 21 pages, 5 figure

Examining the effects of negative work outcomes on telecommuting

Despite telecommuting’s tremendous growth in the last decade, it appears some employees are hesitant to participate in remote work arrangements. Previous research has shown employees to have a negative attitude towards telecommuting when they perceive the work arrangement offers more disadvantages than advantages (Vega, Anderson, & Kaplan, 2015). In addition, Cooper & Kurland (2002) found that employees often limit the amount of time they spend away from the office working as a telecommuter because they fear becoming professionally isolated. To expand upon these findings, the current study aims to investigate whether the fear of negative work outcomes (social isolation, professional isolation, career harm, job insecurity, long work hours, and coworker resentment) influence employees’ willingness to telecommute or extent to which they participate. This study will further investigate the moderating role of telecommuting normativeness, the extent to which telecommuting is a common and accepted practice, at the department level. Using a snowball sampling method, telecommuters in the United States will self-report their perceptions of negative work outcomes as they relate to their current telecommuting situation. I predict that telecommuters’ perceptions of the negative work outcomes will negatively influence their attitude toward, and subsequent practice of, telecommuting

Exploiting stochastic locality in lattice QCD: hadronic observables and their uncertainties

Because of the mass gap, lattice QCD simulations exhibit stochastic locality: distant regions of the lattice fluctuate independently. There is a long history of exploiting this to increase statistics by obtaining multiple spatially-separated samples from each gauge field; in the extreme case, we arrive at the master-field approach in which a single gauge field is used. Here we develop techniques for studying hadronic observables using position-space correlators, which are more localized, and compare with the standard time-momentum representation. We also adapt methods for estimating the variance of an observable from autocorrelated Monte Carlo samples to the case of correlated spatially-separated samples.Comment: 45 pages, 16 figures, 3 table