2,356 research outputs found
Off-diagonal Yukawa Couplings in the s-channel Charged Higgs Production at LHC
The search for the heavy charged Higgs (mH+ > mtop) has been mainly based on
the off-shell top pair production process. However, resonance production in
s-channel single top events is an important channel to search for this
particle. In a previous work, it was shown that this process, i.e., qq' -> H+
-> tb + h.c., can lead to comparable results to what is already obtained from
LHC searches through gb -> tH- process. What was obtained was, however, based
on diagonal Yukawa couplings between incoming quarks assuming cs as the main
incoming pair due to the CKM matrix element being close to unity. The aim of
this paper is to show that off-diagonal couplings, like cb, may lead to
substantial contributions to the cross section, even if the corresponding CKM
matrix element is two orders of magnitude smaller. For this reason, the cross
section is calculated for each initial state including all diagonal and
off-diagonal terms, and all is finally added together to get the total cross
section which is observed to be ~ 2.7 times larger than what is obtained from
cs initial state. Results are eventually reflected into 95% C.L. exclusion and
discovery contours at different integrated luminosities of LHC. A
reasonable coverage of the parameter space is obtained by the 95% C.L.
exclusion contour.Comment: 12 pages, 10 figure
Clay Minerals Deposit of Halakabad (Sabzevar- Iran)
Clay minerals are expanded in south of Sabzevar. They are identified with light color in the filed. The XRD and XRF chemical and mineralogical studies on the Clay minerals indicated that their main clay minerals are Kaolinite, Illite and Dickite. Pyrophyllite is minor clay mineral. Quartz and Sanidine non clay minerals are present with clay minerals .Ratio of Al2O3 is about 40 per cent, it is very good for industrial minerals .Volcanic rocks are origin clay minerals .Their composition are basic to acidic. In south of Sabzevar town there is a small part of these rocks available which include volcanic and volcaniclastic rocks .Geochemical and petrographic studies showed that their compositions are generally acidic and intermediates and are of Dacite and Rhyolite and Andesite rocks type that have changed into clay minerals
Direct numerical simulation of multi-phase flow in complex media
Tesi en modalitat de compendi de publicacionsIn numerous applications, two-phase liquid-gas transport at sub-millimeter length scales plays a substantial role in the determination of the behavior of the system at hand. As its main application, the present work focuses on the polymer electrolyte membrane (PEM) fuel cells. Desirable performance and operational life-time of this class of high-throughput energy conversion devices requires an effective water management, which per se relies on proper prediction of the water-air transport mechanisms. Such two-phase flow involves interfacial forces and phenomena, like hysteresis, that are associated with the physicochemical properties the liquid, gas, and if present, the solid substrate. In this context, numerical modeling is a viable means to obtain valuable predictive understanding of the transport mechanisms, specially for cases that experimental analyses are complicated and/or prohibitively expensive.
In this work, an efficient finite element/level-set framework is developed for three-dimensional simulation of two-phase flow. In order to achieve a robust solver for practical applications, the physical complexities are consistently included and the involved numerical issues are properly tackled; the pressure discontinuity at the liquid-gas interface is consistently captured by utilizing an enriched finite element space. The method is stabilized within the framework of variational multiscale stabilization technique. A novel treatment is further proposed for the small-cut instability problem. It is shown that the proposed model can provide accurate results minimizing the spurious currents. A robust technique is also developed in order to filter out the possible noises in the level-set field. It is shown that it is a key to prevent irregularities caused by the persistent remnant of the spurious currents. It is shown how the well-established contact-line models can be incorporated into the variational formulation. The importance of the inclusion of the sub-elemental hydrodynamics is also elaborated. The results presented in the present work rely on the combination of the linearized molecular kinetic and the hydrodynamic theories. Recalling the realistic behavior of liquids in contact with solid substrates, the contact--angle hysteresis phenomenon is taken into account by imposing a consistent pinning/unpinning mechanism developed within the framework of the level-set method.
Aside from the main developments, a novel technique is also proposed to significantly improve the accuracy and minimize the the loss in the geometrical features of the interface during the level-set convection based on the back and forth error compensation correction (BFECC) algorithm.
Within the context of this thesis, the numerical model is validated for various cases of gas bubble in a liquid and liquid droplets in a gas. For the latter scenario, besides free droplets, the accuracy of the proposed numerical method is assessed for capturing the dynamics droplets spreading on solid substrates. The performance of the model is then analyzed for the capturing the configuration of a water droplet on an inclined substrate in the presence the contact--angle hysteresis. The proposed method is finally employed to simulate the dynamics of a water droplet confined in a gas channel and exposed to air-flow.Existen numerosas aplicaciones industriales en las que transporte bifásico (líquido-gas) a escalas submilimétricas resulta crucial para la determinación del comportamiento del sistema en cuestión. Entre todas ellas, el presente trabajo se centra en las pilas de combustible con membrana de electrolito polimérico (PEMFC). El rendimiento deseable y la vida útil operativa de esta clase de dispositivos de conversión de energía de alto rendimiento requieren una gestión eficaz del agua (conocida como “water management”), que per se depende de la predicción adecuada de los mecanismos de transporte de agua y aire. Así pues, el análisis del flujo microfluídico de dos fases obliga considerar fuerzas y fenómenos interfaciales, tales como la histéresis, que están asociados con las propiedades fisicoquímicas del líquido, el gas y, si está presente, el sustrato sólido. En este contexto, la modelización numérica es una alternativa viable para obtener una predicción precisa de los mecanismos de transporte, especialmente en aquellos casos en los que los análisis experimentales son prohibitivos, ya sea por su complejidad o coste económico. En este trabajo, se desarrolla un marco eficiente, basado en la combinación del método de elementos finitos y el método de “level-set”, para la simulación tridimensional de flujos bifásicos. Con el fin de lograr una herramienta numérica robusta para aplicaciones prácticas, las complejidades físicas se incluyen consistentemente y los problemas numéricos involucrados se abordan adecuadamente. Concretamente, la discontinuidad de la presión en la interfaz líquido-gas se captura consistentemente utilizando un espacio de elementos finitos enriquecido. La estabilización del método se consigue mediante la introducción de la técnica de multiescalas variacionales. Asimismo, se propone también un tratamiento novedoso para el problema de la inestabilidad de tipo “small-cut”. Se muestra que el modelo propuesto puede proporcionar resultados precisos minimizando las corrientes espurias en la interfaz liquido-gas. Complementariamente, se presenta una nueva metodología para filtrar el ruido en el campo de “level-set”. Esta metodología resulta ser crucial para prevenir las irregularidades provocadas por el remanente persistente de las corrientes espurias. El comportamiento de la línea de contacto es considerado a través de la inclusión los modelos correspondientes en la formulación variacional. A este respecto, el presente trabajo aborda la importancia de la inclusión de la hidrodinámica subelemental. Los resultados presentados se basan en la combinación de la cinética molecular linealizada y las teorías hidrodinámicas. Para representación del comportamiento realista de los líquidos en contacto con sustratos sólidos, el fenómeno de histéresis del ángulo de contacto se tiene en cuenta imponiendo un mecanismo de anclado / desanclado consistente desarrollado en el marco del método de level-set. Aparte de los desarrollos principales, también se propone una técnica novedosa para la convección de la función ”level-set”. Ésta permite mejorar significativamente la precisión, minimizando a su vez la pérdida en las características geométricas de la interfaz asociadas al transporte. Esta nueva metodología está basada en el algoritmo de corrección de compensación de errores (BFECC). La herramienta numérica desarrollada en esta tesis es validada para varios casos que involucran burbujas de gas en un líquido y pequeñas gotas de líquido en un gas. Para el último escenario, además de las gotas libres, se evalúa la precisión de la herramienta propuesta para capturar la dinámica de las gotas sobre sustratos sólidos. A continuación, se analiza el rendimiento del modelo para capturar la configuración de una gota de agua sobre un sustrato inclinado en presencia de la histéresis del ángulo de contacto. El método propuesto finalmente se aplicaPostprint (published version
State transfer based on classical nonseparability
We present a state transfer protocol that is mathematically equivalent to
quantum teleportation, but uses classical nonseparability instead of quantum
entanglement. In our implementation we take advantage of nonseparability among
three parties: orbital angular momentum (OAM), polarization, and the radial
degrees of freedom of a beam of light. We demonstrate the transfer of arbitrary
OAM states, in the subspace spanned by any two OAM states, to the polarization
of the same beam
ANTIQUE: A Non-Factoid Question Answering Benchmark
Considering the widespread use of mobile and voice search, answer passage
retrieval for non-factoid questions plays a critical role in modern information
retrieval systems. Despite the importance of the task, the community still
feels the significant lack of large-scale non-factoid question answering
collections with real questions and comprehensive relevance judgments. In this
paper, we develop and release a collection of 2,626 open-domain non-factoid
questions from a diverse set of categories. The dataset, called ANTIQUE,
contains 34,011 manual relevance annotations. The questions were asked by real
users in a community question answering service, i.e., Yahoo! Answers.
Relevance judgments for all the answers to each question were collected through
crowdsourcing. To facilitate further research, we also include a brief analysis
of the data as well as baseline results on both classical and recently
developed neural IR models
Digital spiral object identification using random light
Photons that are entangled or correlated in orbital angular momentum have
been extensively used for remote sensing, object identification and imaging. It
has recently been demonstrated that intensity fluctuations give rise to the
formation of correlations in the orbital angular momentum components and
angular positions of random light. Here, we demonstrate that the spatial
signatures and phase information of an object, with rotational symmetries, can
be identified using classical orbital angular momentum correlations in random
light. The Fourier components imprinted in the digital spiral spectrum of the
object, measured through intensity correlations, unveil its spatial and phase
information. Sharing similarities with conventional compressive sensing
protocols that exploit sparsity to reduce the number of measurements required
to reconstruct a signal, our technique allows sensing of an object with fewer
measurements than other schemes that use pixel-by-pixel imaging. One remarkable
advantage of our technique is the fact that it does not require the preparation
of fragile quantum states of light and works at both low- and high-light
levels. In addition, our technique is robust against environmental noise, a
fundamental feature of any realistic scheme for remote sensing.Comment: 5 pages, 4 figure
Wigner distribution of twisted photons
We present the first experimental characterization of the azimuthal Wigner
distribution of a photon. Our protocol fully characterizes the transverse
structure of a photon in conjugate bases of orbital angular momentum (OAM) and
azimuthal angle (ANG). We provide a test of our protocol by characterizing pure
superpositions and incoherent mixtures of OAM modes in a seven-dimensional
space. The time required for performing measurements in our scheme scales only
linearly with the dimension size of the state under investigation. This time
scaling makes our technique suitable for quantum information applications
involving a large number of OAM states
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