Dirac Gauginos in Supersymmetry -- Suppressed Jets + MET Signals: A Snowmass Whitepaper

We consider the modifications to squark production in the presence of a naturally heavier Dirac gluino. First generation squark production is highly suppressed, providing an interesting but challenging signal find or rule out. No dedicated searches for supersymmetry with a Dirac gluino have been performed, however a reinterpretation of a "decoupled gluino" simplified model suggests the bounds on a common first and second generation squark mass is much smaller than in the MSSM: \lsim 850 GeV for a massless LSP, and no bound for an LSP heavier than about 300 GeV. We compare and contrast the squark production cross sections between a model with a Dirac gluino and one with a Majorana gluino, updating earlier results in the literature to a $pp$ collider operating at $\sqrt{s} = 14$ and 33 TeV. Associated production of squark+gluino is likely very small at $\sqrt{s} = 14$ TeV, while is a challenging but important signal at even higher energy $pp$ colliders. Several other salient implications of Dirac gauginos are mentioned, with some thought-provoking discussion as it regards the importance of the various experiments planned or proposed.Comment: 10 pages, 6 figures; this Snowmass Whitepaper has been submitted to arXiv at the request of the Snowmass convener

The Implications of Information Asymmetry for the Achievement of Australia's National Water Objectives

On 29th April 2008, Senator Penny Wong outlined details of Water for the Future; the Rudd Government’s $12.9 billion plan to secure the long term water supply of all Australians. Funding under Water for the Future will be used to support significant water reform across the country. In order to formulate strategies to achieve the objectives of the Plan, decision makers will require information related to the relative profitability of different irrigation activities, such as production costs and returns, as well as the potential irrigator response to and impacts of reductions in water availability or changes to water policy more generally. The aim of this paper is to highlight the potential for unexpected outcomes to arise from policies which are formulated in a world of information asymmetry. The heterogeneity of irrigation sectors and indeed individual irrigators within these sectors mean that actual impacts or responses will vary significantly between sectors/individuals. Hence while governments may try to predict the potential consequences/impacts of changes to water policy, the resulting outcomes may be far from what was intended.Crop Deaths, Irrigator Behaviour, Economic Assessment, Water Policy, Resource /Energy Economics and Policy,

Natural Supersymmetry and Implications for Higgs physics

We re-analyze the LHC bounds on light third generation squarks in Natural Supersymmetry, where the sparticles have masses inversely proportional to their leading-log contributions to the electroweak symmetry breaking scale. Higgsinos are the lightest supersymmetric particles; top and bottom squarks are the next-to-lightest sparticles that decay into both neutral and charged Higgsinos with well-defined branching ratios determined by Yukawa couplings and kinematics. The Higgsinos are nearly degenerate in mass, once the bino and wino masses are taken to their natural (heavy) values. We consider three scenarios for the stop and sbottom masses: (I) $\tilde{t}_R$ is light, (II) $\tilde{t}_L$ and $\tilde{b}_L$ are light, and (III) $\tilde{t}_R$, $\tilde{t}_L$, and $\tilde{b}_L$ are light. Dedicated stop searches are currently sensitive to Scenarios II and III, but not Scenario I. Sbottom-motivated searches ($2 b + \rm{MET}$) impact both squark flavors due to \tilde{t} \ra b \charp_1 as well as \tilde{b} \ra b \neut_{1,2}, constraining Scenarios I and III with somewhat weaker constraints on Scenario II. The totality of these searches yield relatively strong constraints on Natural Supersymmetry. Two regions that remain are: (1) the "compressed wedge", where $(m_{\tilde{q}} - |\mu|)/m_{\tilde{q}} \ll 1$, and (2) the "kinematic limit" region, where m_{\tilde{q}} \gsim 600-750 GeV, at the kinematic limit of the LHC searches. We calculate the correlated predictions for Higgs physics, demonstrating that these regions lead to distinct predictions for the lightest Higgs couplings that are separable with \simeq 10% measurements. We show that these conclusions remain largely unchanged once the MSSM is extended to the NMSSM in order to naturally obtain a large enough mass for the lightest Higgs boson consistent with LHC data.Comment: 18 pages, 8 figure

Electrical properties and vapour sensing characteristics of a novel metal-polymer composite

Quantum Tunnelling Composite (QTC) is a metal polymer composite, commercialised and produced using a patented manufacture process. This process ensures that the metal particles within an elastomerie polymer matrix maintain a highly fractal surface morphology where nano-scale point features are retained on the particles and are coated in polymer. This structure provides unique electronic behaviour including very high resistivity, of order 10 ΜΩ, above the expected percolation threshold and an exponential increase in conductivity under all types of mechanical deformation. Increase in sample compression leads to a lower electrical resistance through the material. Current-voltage characteristics show a hysteresis effect due to current storage in the QTC material as a current is passed. The hysteresis is shown to be reduced as the applied compression on the material is increased until an Ohmic regime is reached at very high compressions, above 70% linear compression. At these high compressions Joule heating is also proven to occur as a result of the power dissipated in the sample by I-V cycling. The Joule heating is sufficient to influence the physical characteristics of the sample and expand it, creating a current limiting device. QTC samples loaded with acicular electro-conductive particles in small fractions, less than 10% by weight, showed less sensitivity to applied compression in terms of electrical response. These samples appear to exhibit less white noise characteristics and indicate a combination of field assisted quantum tunnelling and percolation mechanism, Intrinsically conductive QTC samples were developed. These were made using QTC granules mixed into a polymer solvent solution. Upon depositing onto electrodes the solvent was allowed to evaporate leaving the constituent polymer binding the QTC granules together, compressing them into a conductive state. Samples were exposed to volatile organic compound (VOC) vapours in the concentration range 10 ppm to 100,000 ppm, causing swelling and void filling in the binding polymer. Combinations of these processes caused an increase in sample resistance, from ~50 Ω to excess of 10 ΜΩ. Sample composition and physical parameters have significant effect upon the response characteristics of the sensors. A system of experiments was undertaken and optimum sample composition was determined. Response to environmental changes were investigated^ namely temperature response and response to varying concentration of exposed solvent. It was found that samples produced using Polyphenylene Oxide ( PPO) and Polyvinyl Chloride (PVC) based binding polymer were more resistant to temperature change from 30 С to 80 С due to their molecular structures. Sensor response to different vapour concentrations was found to exhibit two distinct response regimes. High concentration exposures were found to exhibit a swelling mechanism with a CASE-II diffusion model fitting the data well. Whereas at low concentrations a void-filling based change in sample dielectric constant was attributed to the electronic response to vapour exposure. These predictions were also confirmed using a Quartz Crystal Microbalance (QCM) to measure mass uptake of vapour molecules and polymer density under similar test conditions