11,688 research outputs found

    Decay of Z into Three Pseudoscalar Bosons

    Get PDF
    We consider the decay of the ZZ boson into three pseudoscalar bosons in a general two-Higgs-doublet model. Assuming mAm_A to be very small, and that of the two physical neutral scalar bosons h1h_1 and h2h_2, AA only couples to ZZ through h1h_1, we find the ZAAAZ \to A A A branching fraction to be negligible for moderate values of tanβv2/v1\tan \beta \equiv v_2/v_1, if there is no λ5(Φ1Φ2)2+h.c.\lambda_5 (\Phi_1^\dagger \Phi_2)^2 + h.c. term in the Higgs potential; otherwise there is no absolute bound but very large quartic couplings (beyond the validity of perturbation theory) are needed for it to be observable.Comment: 8 pages including 1 fi

    Probing the Phase-Dependent Conductance and Nonequilibrium Properties of Josephson Junctions by Means of Flux Entry into Weakly Closed Loops

    Get PDF
    Numerical simulations have shown that the relative number of flux quanta which penetrate a weakly closed superconducting loop depends upon the magnitude and sign of the phase-dependent conductance. We examine the possible use of this dependence as an experimental probe of the cosy term and nonequilibrium properties of Josephson junctions

    A No-Scale Framework for Sub-Planckian Physics

    Full text link
    We propose a minimal model framework for physics below the Planck scale with the following features: (i) it is based on no-scale supergravity, as favoured in many string compactifications, (ii) it incorporates Starobinsky-like inflation, and hence is compatible with constraints from the Planck satellite, (iii) the inflaton may be identified with a singlet field in a see-saw model for neutrino masses, providing an efficient scenario for reheating and leptogenesis, (iv) supersymmetry breaking occurs with an arbitrary scale and a cosmological constant that vanishes before radiative corrections, (v) regions of the model parameter space are compatible with all LHC, Higgs and dark matter constraints.Comment: 6 pages, 2 figures, some minor corrections and additions. Final versio

    From R2R^2 Gravity to No-Scale Supergravity

    Full text link
    We show that R2R^2 gravity coupled conformally to scalar fields is equivalent to the real bosonic sector of SU(N,1)/SU(N)×\timesU(1) no-scale supergravity, where the conformal factor can be identified with the K\"ahler potential, and we review the construction of Starobinsky-like models of inflation within this framework.Comment: 15 pages, version accepted for publicatio

    Starobinsky-like Inflationary Models as Avatars of No-Scale Supergravity

    Full text link
    Models of cosmological inflation resembling the Starobinsky R + R^2 model emerge naturally among the effective potentials derived from no-scale SU(N,1)/SU(N) x U(1) supergravity when N > 1. We display several examples in the SU(2,1)/SU(2) x U(1) case, in which the inflaton may be identified with either a modulus field or a matter field. We discuss how the modulus field may be stabilized in models in which a matter field plays the role of the inflaton. We also discuss models that generalize the Starobinsky model but display different relations between the tilt in the spectrum of scalar density perturbations, n_s, the tensor-to-scalar ratio, r, and the number of e-folds, N_*. Finally, we discuss how such models can be probed by present and future CMB experiments.Comment: 23 pages, 3 figure

    Sensitivity of Building Loss Estimates to Major Uncertain Variables

    Get PDF
    This paper examines the question of which sources of uncertainty most strongly affect the repair cost of a building in a future earthquake. Uncertainties examined here include spectral acceleration, ground-motion details, mass, damping, structural force-deformation behavior, building-component fragility, contractor costs, and the contractor's overhead and profit. We measure the variation (or swing) of the repair cost when each basic input variable except one is taken at its median value, and the remaining variable is taken at its 10th and at its 90th percentile. We perform this study using a 1960s highrise nonductile reinforced-concrete moment-frame building. Repair costs are estimated using the assembly-based vulnerability (ABV) method. We find that the top three contributors to uncertainty are assembly capacity (the structural response at which a component exceeds some damage state), shaking intensity (measured here in terms of damped elastic spectral acceleration, Sa), and details of the ground motion with a given Sa

    Production of methyl ethyl ketone from biomass using a hybrid biochemical/catalytic approach

    Get PDF
    The recent demand for sustainable routes to fuels and chemicals has led to an increased amount of research in conversion of natural resources. A potential approach for conversion of biomass to fuels and chemicals is to combine biochemical and chemical processes. This research used microbial fermentation to produce 2,3-butanediol, which was then converted to methyl ethyl ketone by dehydration over a solid acid catalyst. The fermentation process was performed using the bacteria Klebsiella oxytoca (K.O). 2,3-butanediol then dehydrated to form methyl ethyl ketone on a solid acid catalyst, the proton form of ZSM-5, and heat. The goal was to determine the reaction kinetics of 2,3-butanediol dehydration over ZSM-5, and to demonstrate the hybrid biochemical/thermochemical approach for synthesizing chemicals from biomass. It was found that ZSM-5 produced methyl ethyl ketone with high selectivity (greater than 90%), and could convert fermentative 2,3-butanediol to methyl ethyl ketone. The reaction order of 2,3-butanediol dehydration was found to be slightly large than one, and an activation energy of 32.3 kJ/mol was measured

    Developing and Distributing Essential Medicines to Poor Countries: The DEFEND Proposal

    Get PDF
    The poorest nations of the world suffer from extreme disease burdens, which go largely untreated because weak incomes and the prevailing system of intellectual property rights fail to provide sufficient incentives to develop new treatments and distribute them at low cost. Recent price reductions for HIV/AIDS drugs are encouraging but offer only a limited solution. We discuss the economic tradeoffs involved in supporting drug and vaccine research through exclusive rights and distributing the fruits of that research to poor countries. We offer a proposal to overcome these incentive problems. Our DEFEND ("Developing Economies' Fund for Essential New Drugs") proposal would work within the existing international legal structure but significantly would raise the returns to R&D in critical medicines and expand distribution programs. A public international organization would purchase the license rights for designated areas and distribute the drugs at low cost with a required co-payment from local governments. Furthermore, governments would restrict parallel trade to support desirable price discrimination. Costs would be funded largely by increased foreign assistance from the developed nations, but these costs would be low in relation to current aid budgets. We believe a strong program could be mounted for 8billionto8 billion to 12 billion per year and would be an extremely effective use of foreign aid.Drug pricing; Essential medicines; Parallel imports; Developing countries; Patents
    corecore