2,308 research outputs found
Visible Cascade Higgs Decays to Four Photons at Hadron Colliders
The presence of a new singlet scalar particle a can open up new decay
channels for the Higgs boson, through cascades of the form h -> 2a -> X,
possibly making discovery through standard model channels impossible. If a is
CP-odd, its decay products are particularly sensitive to physics beyond the
standard model. Quantum effects from heavy fields can naturally make gluonic
decay, a -> 2g, the dominant decay mode, resulting in a h -> 4 g decay which is
difficult to observe at hadron colliders, and is allowed by LEP for m_h > 82
GeV. However, there are usually associated decays with photons, either h -> 2g
2gamma or h -> 4gamma, which are more promising. The decay h -> 2g 2gamma only
allows discovery of the a particle and not the Higgs whereas h -> 4gamma is a
clean channel that can discover both particles. We determine what branching
ratios are required for discovery at LHC and find that with 300 fb^-1 of
luminosity, a branching ratio of order 10^-4 is sufficient for a large region
of Higgs masses. Due to a lower expected luminosity of ~ 8 fb^-1, discovery at
the Tevatron requires more than 5 x 10^-3 in branching ratio.Comment: 6 pages, 2 color figures, revtex4 forma
Encountering authority and avoiding trouble: young migrant men’s narratives of negotiation in Europe
Drawing on data from seven European countries (Czech Republic, Finland, France, Germany, Ireland, Italy and the United Kingdom), this article seeks to identify how young migrant men engage with authority and avoid conflict against a backdrop of increasing hostility towards migrants in many European countries. As this article contends, even those with permanent residency status in the host country often find themselves having to justify their legitimacy to carry out daily tasks, resulting in many young male migrants living with feelings of perpetual insecurity. As such, a number of coping strategies are employed by young migrant men in order to assuage such feelings and mitigate potential risks. Focusing on the lived experiences of this group, as described in narrative interviews, our study found that many young migrant men are required to enter into negotiations with authority figures, where there is a considerable power differential. Acting as risk assessors, they find themselves forced to navigate complex and challenging social relations and support networks. We show how self-limiting behaviour intended to avoid or control interactions with authority and the negotiations conducted to minimize the risk of ‘trouble’ by young migrant men not only are problematic in the context of day-to-day activities but can very often have a detrimental impact on their lives
Encountering authority and avoiding trouble: Young migrant men’s narratives of negotiation in Europe
Conditional moment methods for polydisperse cavitating flows
The dynamics of cavitation bubbles are important in many flows, but their
small sizes and high number densities often preclude direct numerical
simulation. We present a computational model that averages their effect on the
flow over larger spatiotemporal scales. The model is based on solving a
generalized population balance equation (PBE) for nonlinear bubble dynamics and
explicitly represents the evolving probability density of bubble radii and
radial velocities. Conditional quadrature-based moment methods (QBMMs) are
adapted to solve this PBE. A one-way-coupled bubble dynamics problem
demonstrates the efficacy of different QBMMs for the evolving bubble
statistics. Results show that enforcing hyperbolicity during moment inversion
(CHyQMOM) provides comparable model-form accuracy to the traditional
conditional method of moments and decreases computational costs by about ten
times for a broad range of test cases. The CHyQMOM-based computational model is
implemented in MFC, an open-source multi-phase and high-order-accurate flow
solver. We assess the effect of the model and its parameters on a two-way
coupled bubble screen flow problem.Comment: 19 pages, 9 figures, submitted to J. Comp. Phy
QBMMlib: A library of quadrature-based moment methods
QBMMlib is an open source Mathematica package of quadrature-based moment
methods and their algorithms. Such methods are commonly used to solve
fully-coupled disperse flow and combustion problems, though formulating and
closing the corresponding governing equations can be complex. QBMMlib aims to
make analyzing these techniques simple and more accessible. Its routines use
symbolic manipulation to formulate the moment transport equations for a
population balance equation and a prescribed dynamical system. However, the
resulting moment transport equations are unclosed. QBMMlib trades the moments
for a set of quadrature points and weights via an inversion algorithm, of which
several are available. Quadratures then closes the moment transport equations.
Embedded code snippets show how to use QBMMlib, with the algorithm
initialization and solution spanning just 13 total lines of code. Examples are
shown and analyzed for linear harmonic oscillator and bubble dynamics problems.Comment: Under review Software
Recommended from our members
Statistical modeling of disease emergence
Infectious diseases seem to be appearing at an unprecedented rate: within the last few years alone, a sequence of novel diseases like MERS-CoV, Chikungunya, and Zika have emerged. Concurrently, a number of previously known diseases have re-emerged like the 2009 H1N1 pandemic and the 2014 Ebola epidemic. While these known and unknown emergence events have all begun with a wildlife or livestock spillover transmission event into humans, they each present unique subsequent public health challenges. Quantitative prediction of either the re-emergence of a known disease or potential for global spread of a novel disease can help optimize public health responses and resource allocation, but these events are usually analyzed in retrospect. In this dissertation, I developed quantitative frameworks that can be used in real-time for predicting disease emergence risk. In Chapter 2, I identified a seasonal trend to pandemic influenza emergence events, and proposed a hypothesis to explain the seasonal patterns and predict pandemic emergence risk for seasonal flu data. In Chapter 3, I developed a framework to both predict the number of imported Zika cases into a region, and subsequently assist public health decision-making during an uncertain outbreak. Finally, in Chapter 4, I developed a method that can be used to update regional transmission risk estimates of a novel disease before transmission occurs. Altogether, the results presented in this dissertation suggest that statistical modeling can be an important tool to assist real-time public health predictions and responses.Ecology, Evolution and Behavio
Nowhere to Run; Nowhere to Hide: The Reality of Being a Law Library Director in Times of Great Opportunity and Significant Challenges
This is an edited version of remarks presented at \u27Nowhere to Run, Nowhere to Hide\u27: The Reality of Being a Law Library Director in Times of Great Opportunity and Significant Challenges, January 5, 2015, at the Association of American Law Schools Annual Meeting, Washington, D.C
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