Constraining the Axion Portal with B -> K l+ l-

We investigate the bounds on axionlike states from flavor-changing neutral current b->s decays, assuming the axion couples to the standard model through mixing with the Higgs sector. Such GeV-scale axions have received renewed attention in connection with observed cosmic ray excesses. We find that existing B->K l+ l- data impose stringent bounds on the axion decay constant in the multi-TeV range, relevant for constraining the "axion portal" model of dark matter. Such bounds also constrain light Higgs scenarios in the next-to-minimal supersymmetric standard model. These bounds can be improved by dedicated searches in B-factory data and at LHCb.Comment: 7 pages, 4 figures; v2: to match version to appear in PR

Testing symmetries in effective models of higher derivative field theories

Higher derivative field theories with interactions raise serious doubts about their validity due to severe energy instabilities. In many cases the implementation of a direct perturbation treatment to excise the dangerous negative-energies from a higher derivative field theory may lead to violations of Lorentz and other symmetries. In this work we study a perturbative formulation for higher derivative field theories that allows the construction of a low-energy effective field theory being a genuine perturbations over the ordinary-derivative theory and having a positive-defined Hamiltonian. We show that some discrete symmetries are recovered in the low-energy effective theory when the perturbative method to reduce the negative-energy degrees of freedom from the higher derivative theory is applied. In particular, we focus on the higher derivative Maxwell-Chern-Simons model which is a Lorentz invariant and parity-odd theory in 2+1 dimensions. The parity violation arises in the effective action of QED$_3$ as a quantum correction from the massive fermionic sector. We obtain the effective field theory which remains Lorentz invariant, but parity invariant to the order considered in the perturbative expansion.Comment: 13 pages, Sec. III, additional references added, P symmetry revised, accepted for publication in PR

Model Uncertainties in a Sharp Leading-Edge Hypersonic Boundary Layer

The effects of uncertainties in the gas-surface interaction and intermolecular interaction models on the hypersonic boundary layer development are investigated using the nonintrusive generalized polynomial chaos method. In particular, uncertainties in the surface shear stress, normal stress, heat flux, flowfield temperature and density resulting from uncertain viscosity exponent, surface temperature and accommodation coefficient are considered. The polynomial chaos expansion approach is used to reconstruct the probability density function, calculate mean, standard deviation and skewness of the dependent variables from the DSMC calculations. The uncertainty analysis shows that surface fluxes and flowfields in the hypersonic boundary layer are more sensitive to the accommodation coefficient than surface temperature or viscosity exponent uncertainty

Effects of Uncertainty in Gas-Surface Interaction on DSMC Simulations of Hypersonic Flows

This study uses the non-intrusive generalized polynomial chaos method to investigate the effects of uncertainties in the gas-surface interaction model on the hypersonic boundary layer flow over a flat plate. In particular, the polynomial chaos method is applied to assess uncertainties in the surface shea, normal stress, heat flux, flowfield temperature and accomodation coefficient. The polynomial chaos approach allows us to estimate probability density functions from fewer flowfield samples than the traditional random Monte Carlo sampling. The flowfield solutions are computed by the DSMC code SMILE. The analysis shows that surface fluxes and flowfields in the hypersonic boundary layer are more sensitive to the accommodation coefficient than surface temperature uncertainty

Asymptotic equivalence of differential equations and asymptotically almost periodic solutions

In this paper we use Rab's lemma [M. Rab, Uber lineare perturbationen eines systems von linearen differentialgleichungen, Czechoslovak Math. J. 83 (1958) 222-229; M. Rab, Note sur les formules asymptotiques pour les solutions d'un systeme d'equations differentielles lineaires, Czechoslovak Math. J. 91 (1966) 127-129] to obtain new sufficient conditions for the asymptotic equivalence of linear and quasilinear systems of ordinary differential equations. Yakubovich's result [V.V. Nemytskii, VX Stepanov, Qualitative Theory of Differential Equations, Princeton University Press, Princeton, New Jersey, 1966; V.A. Yakubovich, On the asymptotic behavior of systems of differential equations, Mat. Sb. 28 (1951) 217-240] on the asymptotic equivalence of a linear and a quasilinear system is developed. On the basis of the equivalence, the existence of asymptotically almost periodic solutions of the systems is investigated. The definitions of biasymptotic equivalence for the equations and biasymptotically almost periodic solutions are introduced. Theorems on the sufficient conditions for the systems to be biasymptotically equivalent and for the existence of biasymptotically almost periodic solutions are obtained. Appropriate examples are constructed

THE FORMALIZED ASSESSMENT OF EFFICIENCY OF THE REGIONAL HIGHER SCHOOL THROUGH THE PRISM OF THE RATIO OF ENTRANCE AND OUTPUT STREAM SIZES

En el contexto de la globalización, aumenta el crecimiento del entorno competitivo a nivel nacional e interregional en el campo del desarrollo de la innovación, el papel de la educación superior como la principal fuente de recursos humanos y la formación del entorno de innovación. El bajo nivel de desarrollo de la educación superior priva a la región de una cierta independencia, colocándola en una dependencia adicional de otros sistemas: regional, nacional, económico, etc. En este sentido, el estudio de las tendencias en el desarrollo de la educación superior en el interregional level es una tarea extremadamente urgente, cuya solución proporcionará un proceso de monitoreo y pronóstico de las perspectivas para el desarrollo de sistemas socioeconómicos a mediano y largo plazo. Al mismo tiempo, a pesar de una amplia gama de trabajos científicos dedicados al problema, todavía no hay unidad en el espacio científico en la esfera de la evaluación formal de la efectividad del desarrollo de los sistemas regionales de educación superior. En este sentido, este estudio propone enfoques dirigidos al apoyo metodológico para resolver el problema. La característica principal del trabajo es el uso de métodos de comparación de valores de flujo de entrada y salida, que caracterizan los parámetros de la escuela superior regional. Utilizando los enfoques de racionamiento de los indicadores analizados y el desarrollo posterior sobre la base de los índices de eficiencia, se llevan a cabo cálculos multicomponentes, evaluando los indicadores, caracterizando el rendimiento del capital invertido de los sistemas regionales de educación superior en forma de una evaluación integrada de su efectividad por 1 rublo de costos financieros. Como resultado de las evaluaciones implementadas, se identifican las regiones del distrito Volga Federal, caracterizadas por posiciones moderadas y fuertes en el campo de la generación de efectos, caracterizando su efectividad en comparación con los recursos financieros invertidos.No contexto da globalização, aumenta o crescimento do ambiente competitivo nos níveis nacional inter-regional no campo do desenvolvimento da inovação, o papel do ensino superior como principal fonte de recursos humanos e a formação do ambiente de inovação. O baixo nível de desenvolvimento do ensino superior priva a região de uma certa independência, colocando-a em dependência adicional de outros sistemas - regional, nacional, econômico etc. A esse respeito, o estudo de tendências no desenvolvimento do ensino superior no nível inter-regional O nível é uma tarefa extremamente urgente, cuja solução proporcionará um processo de monitoramento e previsão das perspectivas para o desenvolvimento de sistemas socioeconômicos a médio e longo prazo.Ao mesmo tempo, apesar de uma ampla gama de trabalhos científicos dedicados ao problema, ainda não há unidade no espaço científico na esfera da avaliação formal da efetividade do desenvolvimento dos sistemas regionais de ensino superior. Nesse sentido, este estudo propõe abordagens voltadas ao suporte metodológico da solução do problema. A principal característica do trabalho é o uso de métodos de comparação dos valores dos fluxos de entrada e saída, caracterizando os parâmetros do ensino superior regional. Utilizando as abordagens de racionamento dos indicadores analisados e o subsequente desenvolvimento com base nos índices de eficiência, são realizados cálculos multicomponentes, avaliando os indicadores, caracterizando o retorno sobre o capital investido dos sistemas regionais de ensino superior na forma de uma avaliação integrada de sua eficácia por 1 rublo de custos financeiros. Como resultado das avaliações implementadas, são identificadas as regiões do distrito Federal do Volga, caracterizadas por posições moderadas e fortes no campo de geração de efeitos, caracterizando sua efetividade em comparação aos recursos financeiros investidos.In the context of globalization, the growth of the competitive environment at the interregional, national levels in the field of innovation development, the role of higher education as the main source of human resources and the formation of the innovation environment increases. The low level of development of higher education deprives the region of a certain independence, placing it in additional dependence on other systems - regional, national, economic, etc. In this regard, the study of trends in the development of higher education at the interregional level is an extremely urgent task, the solution of which will provide a process of monitoring and forecasting the prospects for the development of socio-economic systems in the medium and long term. At the same time, despite a wide range of scientific works devoted to the problem, there is still no unity in the scientific space in the sphere of formal evaluation of the effectiveness of the development of regional higher education systems. In this regard, this study proposes approaches aimed at methodological support of solving the problem. The main feature of the work is the use of methods of comparison of input and output stream values, characterizing the parameters of the regional higher school. Using the approaches of rationing of the analyzed indicators and the subsequent development on this basis of the efficiency indices, multicomponent calculations are carried out, evaluating the indicators, characterizing the return on invested capital of regional higher education systems in the form of an integrated assessment of their effectiveness per 1 ruble of financial costs. As a result of the implemented assessments, the regions of the Volga Federal district are identified, characterized by moderate and strong positions in the field of generating effects, characterizing their effectiveness in comparison with the invested financial resources. &nbsp

Molecular Actuators in Action: Electron-Transfer-Induced Conformation Transformation in Cofacially Arrayed Polyfluorenes

There is much current interest in the design of molecular actuators, which undergo reversible, controlled motion in response to an external stimulus (light, heat, oxidation, etc.). Here we describe the design and synthesis of a series of cofacially arrayed polyfluorenes (MeFnHm) with varied end-capping groups, which undergo redox-controlled electromechanical actuation. Such cofacially arrayed polyfluorenes are a model molecular scaffold to investigate fundamental processes of charge and energy transfer across a π-stacked assembly, and we show with the aid of NMR and optical spectroscopies, X-ray crystallography and DFT calculations that in the neutral state the conformation of MeFnH1 and MeFnH2 is open rather than cofacial, with a conformational dependence that is highly influenced by the local environment. Upon (electro)chemical oxidation, these systems undergo a reversible transformation into a closed fully π-stacked conformation, driven by charge-resonance stabilization of the cationic charge. These findings are expected to aid the design of novel wire-like cofacially arrayed systems capable of undergo redox-controlled actuation