2,165 research outputs found
Electroweak gauge boson polarisation at the LHC
We study the polarisation of gauge bosons produced at the LHC. Polarisation
effects for W bosons manifest themselves in the angular distributions of the
lepton and in the distributions of lepton transverse momentum and missing
transverse energy. The distributions also depend on the selection cuts, with
kinematic effects competing with polarisation effects. The polarisation is
discussed for a range of different processes producing W bosons: W+jets, W from
top (single and pair) production, W pair production and W production in
association with a Z or Higgs boson. The relative contributions of the
different polarisation states varies from process to process, reflecting the
dynamics of the underlying hard-scattering process. We also present results for
the polarisation of the Z boson produced in association with QCD jets at the
LHC, and comment on the differences between W and Z production.Comment: 27 pages, 25 figure
The point of maximum curvature as a marker for physiological time series
We present a geometric analysis of the model of Stirling. In particular we analyze the curvature of a heart rate time series in response to a step like increment in the exercise intensity. We present solutions for the point of maximum curvature which can be used as a marker of physiological interest. This marker defines the point after which the heart rate no longer continues to rapidly rise and instead follows either a steady state or slow rise. These methods are then applied to find analytic solutions for a mono exponential model which is commonly used in the literature to model the response to a moderate exercise intensity. Numerical solutions are then found for the full model and parameter values presented in Stirling
Risk, precaution and science: towards a more constructive policy debate. Talking point on the precautionary principle
Few issues in contemporary risk policy are as momentous or contentious as the precautionary principle. Since it first emerged in German environmental policy, it has been championed by environmentalists and consumer protection groups, and resisted by the industries they oppose (Raffensperger & Tickner, 1999). Various versions of the principle now proliferate across different national and international jurisdictions and policy areas (Fisher, 2002). From a guiding theme in European Commission (EC) environmental policy, it has become a general principle of EC law (CEC, 2000; Vos & Wendler, 2006). Its influence has extended from the regulation of environmental, technological and health risks to the wider governance of science, innovation and trade (O'Riordan & Cameron, 1994)
HepData and JetWeb: HEP data archiving and model validation
The CEDAR collaboration is extending and combining the JetWeb and HepData
systems to provide a single service for tuning and validating models of
high-energy physics processes. The centrepiece of this activity is the fitting
by JetWeb of observables computed from Monte Carlo event generator events
against their experimentally determined distributions, as stored in HepData.
Caching the results of the JetWeb simulation and comparison stages provides a
single cumulative database of event generator tunings, fitted against a wide
range of experimental quantities. An important feature of this integration is a
family of XML data formats, called HepML.Comment: 4 pages, 0 figures. To be published in proceedings of CHEP0
HepForge: A lightweight development environment for HEP software
Setting up the infrastructure to manage a software project can become a task
as significant writing the software itself. A variety of useful open source
tools are available, such as Web-based viewers for version control systems,
"wikis" for collaborative discussions and bug-tracking systems, but their use
in high-energy physics, outside large collaborations, is insubstantial.
Understandably, physicists would rather do physics than configure project
management tools.
We introduce the CEDAR HepForge system, which provides a lightweight
development environment for HEP software. Services available as part of
HepForge include the above-mentioned tools as well as mailing lists, shell
accounts, archiving of releases and low-maintenance Web space. HepForge also
exists to promote best-practice software development methods and to provide a
central repository for re-usable HEP software and phenomenology codes.Comment: 3 pages, 0 figures. To be published in proceedings of CHEP06. Refers
to the HepForge facility at http://hepforge.cedar.ac.u
Exploring the efficacy of Facebook groups for collective occupant learning about using their homes
The need for quality learning about how to use a home has been an issue gradually emerging from building performance evaluation (BPE) studies carried out in occupied energy efficient homes (Brown & Cole, 2009; Day & Gunderson, 2014). The BPE gap between the internal environment control as intended by designers and the actual inhabitant practices is associated with unpredicted energy consumption and poor indoor air quality (Balvers et al., 2012). The key inhabitant related causes of the ‘performance gap’ are a discrepancy between user needs and design intentions, lack of user understanding and skills to interact with the available controls and insufficient maintenance. These findings indicate that modifying tacit home use practices, adjusting them to new, more technically advanced contexts, is still not sufficiently addressed by the current learning opportunities offered by the professional actors. This paper explores how self-organised closed Facebook Groups set up independently by the residents of two UK case study urban developments have become supportive environments for such learning
Anomalous quartic WWgamma gamma, ZZgamma gamma, and trilinear WWgamma couplings in two-photon processes at high luminosity at the LHC
We study the W/Z pair production via two-photon exchange at the LHC and give
the sensitivities on trilinear and quartic gauge anomalous couplings between
photons and W/Z bosons for an integrated luminosity of 30 and 200 fb^{-1}. For
simplicity and to obtain lower backgrounds, only the leptonic decays of the
electroweak bosons are considered.Comment: 22 pages, 17 figures, sumitted to Phys. Rev.
The impact of hydrothermal carbonisation on the char reactivity of biomass
Hydrothermal carbonisation (HTC) is an attractive biomass pre-treatment as it produces a coal-like fuel, can easily process wet biomass and wastes, and lowers the risk of slagging and fouling in pulverised fuel (PF) combustion boilers. One of the major factors in determining the suitability of a fuel as a coal replacement for PF combustion is matching the char reactivity and volatile matter content to that of coals, as these significantly affect heat release and flame stability. The char reactivity of wood and olive cake biocoals and their respective drop tube furnace chars have been studied using thermogravimetric analysis in comparison to other biomass fuels and high-volatile bituminous coal. It was found that HTC reduces the reactivity of biomass, and in the case of HTC of wood pellets the resulting biocoal has a char reactivity similar to that of high-volatile bituminous coal. Proximate analysis, X-ray fluorescence analysis, and textural characterisation were used to show that this effect is caused primarily by removal of catalytic alkali and alkaline earth metals. Subsequent torrefaction of the wood biocoals was performed to tailor their volatile matter content to match that of sub-bituminous and high volatile bituminous coals without major impact on char reactivity
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