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Letteratura scientifica selezionata sul tema "Scattering conforme"

Autore: Grafiati
Pubblicato: 31 agosto 2024

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Articoli di riviste sul tema "Scattering conforme"

1

Semenova, L. E. "The Raman and hyper-Raman scatterings of light by LO-phonons in a CdS crystal under excitation near resonance with the An=2 and Bn=1 exciton levels". Journal of Physics: Conference Series 2249, n. 1 (1 aprile 2022): 012009. http://dx.doi.org/10.1088/1742-6596/2249/1/012009.

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Abstract The theoretical treatment of the scattering of light by LO-phonons under one-photon and two-photon excitation near resonance with the An=2 and Bn=1 exciton levels in a CdS crystal is given. The influence of the complex structure of the top valence band on these levels is taken into account by the use of the perturbation theory. Assumption of the nonzero matrix elements of the dipole transitions between the A and B sub-bands leads to the fact that the linear combinations of the 1s and 2p exciton wave functions conform to the two “perturbed” energy levels. The possible manifestations of this mixing of states in the resonance Raman and hyper-Raman scatterings are considered.
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2

ANTONIADIS, IGNATIOS, e GEORGE SAVVIDY. "CONFORMAL INVARIANCE OF TENSOR BOSON TREE AMPLITUDES". Modern Physics Letters A 27, n. 18 (14 giugno 2012): 1250103. http://dx.doi.org/10.1142/s0217732312501039.

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The BCFW recursion relation allows to find out the tree-level scattering amplitudes for gluons and tensor gauge bosons in generalized Yang–Mills theory. We demonstrate that the corresponding MHV amplitudes for the tensor gauge bosons of spin-s and n gluons are invariant under conformal group of transformations. This is highly unexpected result for the higher-spin particles, in particular this is not true for the scattering amplitudes of gravitons. We discuss and compare the tree-level scattering amplitudes for the charged tensor bosons with the corresponding scattering amplitudes for gravitons, stressing their differences and similarities.
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3

MASON, LIONEL J., e JEAN-PHILIPPE NICOLAS. "CONFORMAL SCATTERING AND THE GOURSAT PROBLEM". Journal of Hyperbolic Differential Equations 01, n. 02 (giugno 2004): 197–233. http://dx.doi.org/10.1142/s0219891604000123.

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We work on a class of non-stationary vacuum space-times admitting a conformal compactification that is smooth at null and timelike infinity. Via a conformal transformation, the existence of a scattering operator for field equations is interpreted as the well-posedness of a Goursat problem on null infinity. We solve the Goursat problem in the case of Dirac and Maxwell fields. The case of the wave equation is also discussed and it is shown why the method cannot be applied at present. Then the conformal scattering operator is proved to be equivalent to an analytical scattering operator defined in terms of classical wave operators.
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Graham, C. Robin, e Maciej Zworski. "Scattering matrix in conformal geometry". Inventiones Mathematicae 152, n. 1 (1 aprile 2003): 89–118. http://dx.doi.org/10.1007/s00222-002-0268-1.

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5

Rachwał, Lesław. "Conformal Symmetry in Field Theory and in Quantum Gravity". Universe 4, n. 11 (15 novembre 2018): 125. http://dx.doi.org/10.3390/universe4110125.

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Conformal symmetry always played an important role in field theory (both quantum and classical) and in gravity. We present construction of quantum conformal gravity and discuss its features regarding scattering amplitudes and quantum effective action. First, the long and complicated story of UV-divergences is recalled. With the development of UV-finite higher derivative (or non-local) gravitational theory, all problems with infinities and spacetime singularities might be completely solved. Moreover, the non-local quantum conformal theory reveals itself to be ghost-free, so the unitarity of the theory should be safe. After the construction of UV-finite theory, we focused on making it manifestly conformally invariant using the dilaton trick. We also argue that in this class of theories conformal anomaly can be taken to vanish by fine-tuning the couplings. As applications of this theory, the constraints of the conformal symmetry on the form of the effective action and on the scattering amplitudes are shown. We also remark about the preservation of the unitarity bound for scattering. Finally, the old model of conformal supergravity by Fradkin and Tseytlin is briefly presented.
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JOUDIOUX, JÉRÉMIE. "CONFORMAL SCATTERING FOR A NONLINEAR WAVE EQUATION". Journal of Hyperbolic Differential Equations 09, n. 01 (marzo 2012): 1–65. http://dx.doi.org/10.1142/s0219891612500014.

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We establish a geometric scattering theory for a conformally invariant nonlinear wave equation on an asymptotically simple space-time. The scattering operator is defined via some trace operators at null infinity, and the proof is decomposed into three steps. A priori linear estimates are obtained via an adaptation of the Morawetz vector field to the Schwarzschild space-time and a method introduced by Hörmander for the Goursat problem. A well-posedness theorem for the characteristic Cauchy problem on a light cone at infinity is then obtained. Its proof requires a control of the nonlinearity that is uniform in time and follows from, both, an estimate of the Sobolev constant and a decay assumption on the nonlinearity of the equation. Finally, the trace operators on conformal infinity are introduced and allow us to define the conformal scattering operator of interest.
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Shao, Yang, Zhen Peng, Kheng Hwee Lim e Jin-Fa Lee. "Non-conformal domain decomposition methods for time-harmonic Maxwell equations". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, n. 2145 (4 aprile 2012): 2433–60. http://dx.doi.org/10.1098/rspa.2012.0028.

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We review non-conformal domain decomposition methods (DDMs) and their applications in solving electrically large and multi-scale electromagnetic (EM) radiation and scattering problems. In particular, a finite-element DDM, together with a finite-element tearing and interconnecting (FETI)-like algorithm, incorporating Robin transmission conditions and an edge corner penalty term , are discussed in detail. We address in full the formulations, and subsequently, their applications to problems with significant amounts of repetitions. The non-conformal DDM approach has also been extended into surface integral equation methods. We elucidate a non-conformal integral equation domain decomposition method and a generalized combined field integral equation method for modelling EM wave scattering from non-penetrable and penetrable targets, respectively. Moreover, a plane wave scattering from a composite mockup fighter jet has been simulated using the newly developed multi-solver domain decomposition method.
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DAI, Yan, e Chao SUN. "Scattering characteristics analysis of conformal array based on sound field prediction method". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 40, n. 3 (giugno 2022): 568–75. http://dx.doi.org/10.1051/jnwpu/20224030568.

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In order to study the problem that the array manifold of conformal arrays deviates from the ideal value due to the sound scattering caused by the rigid baffles of arrays, in this paper, the influence of the scattering phenomenon caused by the rigid baffle on the receiving response of array is analyzed by using sound field prediction method based on a conformal array-semi-cylindrical volume array. The sound field distribution of conformal array at different angles is calculated by using the sound field modeling and simulation. Based on the above distribution, an actual array manifold is constructed under consideration of rigid barrier, and its variation under the influence of scattered sound is analyzed. The variation is described by two physical quantities defined in this paper: the first-order response composed of amplitude and phase and the second-order response composed of cross-correlation. Simulation shows that compared with the ideal model, the scattered signals generated by rigid baffles on conformal array varies with the azimuth and signal-to-noise ratio(SNR), which further leads to the deviation of each hydrophone of conformal array. The experimental data verifies that the simulation results are basically consistent with the actual situation. The effect of the scattering on the conformal array should be considered when designing and performing in practice.
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Jackson, Steven, Lauren McGough e Herman Verlinde. "Conformal bootstrap, universality and gravitational scattering". Nuclear Physics B 901 (dicembre 2015): 382–429. http://dx.doi.org/10.1016/j.nuclphysb.2015.10.013.

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Akulinichev, S. V., R. D. Ilic e I. A. Yakovlev. "Conformal proton therapy with passive scattering". Radiotherapy and Oncology 118 (febbraio 2016): S2. http://dx.doi.org/10.1016/s0167-8140(16)30004-4.

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Più fonti

Tesi sul tema "Scattering conforme"

1

Joudioux, Jérémie. "Problème de Cauchy caractéristique et scattering conforme en relativité générale". Phd thesis, Université de Bretagne occidentale - Brest, 2010. http://tel.archives-ouvertes.fr/tel-00517339.

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L'étude présentée dans ce travail de thèse aborde deux aspects du problème de Cauchy caractéristique en relativité générale. D'une part, une formule intégrale pour le problème de Cauchy caractéristique pour l'équation de Dirac est établie, généralisant les travaux de Penrose en espace-temps courbe. Ayant adapté le cadre fonctionnel pour obtenir une théorie des distributions adaptée à la structure algébriques des spineurs, le formalisme Geroch-Held-Penrose est utilisé pour décrire de la manière la plus précise possible la formule intégrale. La formule de Penrose en spin arbitraire sur l'espace-temps de Minkowski est retrouvée. D'autre part, une théorie de scattering conforme pour une équation des ondes non linéaire conformément invariante sur un espace asymptotiquement simple est construite. En effectuant un rééchelonnement conforme, l'espace-temps est complété en lui ajoutant une frontière constituée de deux hypersurfaces caractéristiques représentant respectivement les extrémités passées et futures des géodésiques de type lumière. Le comportement asymptotique des champs s'obtient alors en considérant les traces des solutions de l'équation conforme sur ces bords. L'inversibilité des opérateurs de trace s'obtient alors en résolvant un problème de Cauchy caractéristique sur ce bord et l'opérateur de scattering conforme par composition de ces opérateurs de trace.
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Pham, Truong Xuan. "Peeling et scattering conforme dans les espaces-temps de la relativité générale". Thesis, Brest, 2017. http://www.theses.fr/2017BRES0034/document.

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Nous étudions l’analyse asymptotique en relativité générale sous deux aspects: le peeling et le scattering (diffusion) conforme. Le peeling est construit pour les champs scalaires linéaire et non-linéaires et pour les champs de Dirac en espace-temps de Kerr (qui est non-stationnaire et à symétrie simplement axiale), généralisant les travaux de L. Mason et J-P. Nicolas (2009, 2012). La méthode des champs de vecteurs (estimations d’énergie géométriques) et la technique de compactification conforme sont développées. Elles nous permettent de formuler les définitions du peeling à tous ordres et d’obtenir les données initiales optimales qui assurent ces comportements. Une théorie de la diffusion conforme pour les équations de champs sans masse de spîn n/2 dans l’espace-temps de Minkowski est construite.En effectuant les compactifications conformes (complète et partielle), l’espace-temps est complété en ajoutant une frontière constituée de deux hypersurfaces isotropes représentant respectivement les points limites passés et futurs des géodésiques de type lumière. Le comportement asymptotique des champs s’obtient en résolvant le problème de Cauchy pour l’équation rééchelonnée et en considérant les traces des solutions sur ces bords. L’inversibilité des opérateurs de trace, qui associent le comportement asymptotique passé ou futur aux données initiales, s’obtient en résolvant le problème de Goursat sur le bord conforme. L’opérateur de diffusion conforme est alors obtenu par composition de l’opérateur de trace futur avec l’inverse de l’opérateur de trace passé
This work explores two aspects of asymptotic analysis in general relativity: peeling and conformal scattering.On the one hand, the peeling is constructed for linear and nonlinear scalar fields as well as Dirac fields on Kerr spacetime, which is non-stationary and merely axially symmetric. This generalizes the work of L. Mason and J-P. Nicolas (2009, 2012). The vector field method (geometric energy estimates) and the conformal technique are developed. They allow us to formulate the definition of the peeling at all orders and to obtain the optimal space of initial data which guarantees these behaviours. On the other hand, a conformal scattering theory for the spin-n/2 zero rest-mass equations on Minkowski spacetime is constructed. Using the conformal compactifications (full and partial), the spacetime is completed with two null hypersurfaces representing respectively the past and future end points of null geodesics. The asymptotic behaviour of fields is then obtained by solving the Cauchy problem for the rescaled equation and considering the traces of the solutions on these hypersurfaces. The invertibility of the trace operators, that to the initial data associate the future or past asymptotic behaviours, is obtained by solving the Goursat problem on the conformal boundary. The conformal scattering operator is then obtained by composing the future trace operator with the inverse of the past trace operator
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3

Mokdad, Mokdad. "Champs de Maxwell en espace-temps de Reissner - Nordstr∫m- De Sitter : décroissance et scattering conforme". Thesis, Brest, 2016. http://www.theses.fr/2016BRES0060/document.

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Nous étudions les champs de Maxwell à l'extérieur de trous noirs de Reissner-Nordstrom-de Sitter. Nous commençons par étudier la géométrie de ces espaces-temps : nous donnons une condition sous laquelle la métrique admet trois horizons puis dans ce cadre nous construisons l'extension analytique maximale d'un trou noir de Reissner-Nordstrom-de Sitter. Nous donnons ensuite une description générale des champs de Maxwell en espace-temps courbe, de leur décomposition en composantes spinorielle ainsi que de leur énergie. La première étude analytique établit la décroissance ponctuelle de champs de Maxwell à l'extérieur d'un trou noir de Reissner-Nordstrom-de Sitter ainsi que la décroissance uniforme de l'énergie sur un hyperboloïde qui s'éloigne dans le futur. Ce chapitre utilise des méthodes de champs de vecteurs (estimations d'énergie géométriques) dans l'esprit des travaux de Pieter Blue. Enfin nous construisons une théorie du scattering conforme pour les champs de Maxwell à l'extérieur du trou noir. Ceci consiste en la résolution du problème de Goursat pour les champs de Maxwell à la frontière isotrope de l'extérieur du trou noir, constituée des horizons du trou noir et horizons cosmologiques futurs et passés. Les estimations de décroissance uniforme de l'énergie sont cruciales dans cette partie
We study Maxwell fields on the exterior of Reissner-Nordstrom-de Sitter black holes. We start by studying the geometry of these spacetimes: we give the condition under which the metric admits three horizons and in this case we construct the maximal analytic extension of the Reissner-Nordstrom-de Sitter black hole. We then give a general description of Maxwell fields on curves spacetimes, their decomposition into spin components, and their energies. The first result establishes the pointwise decay of the Maxwell field in the exterior of a Reissner-Nordstrom-de Sitter black hole, as well as the uniform decay of the energy flux across a hyperboloid that recedes in the future. This chapter uses the vector fields methods (geometric energy estimates) in the spirit of the work of Pieter Blue. Finally, we construct a conformal scattering theory for Maxwell fields in the exterior of the black hole. This amounts to solving the Goursat problem for Maxwell fields on the null boundary of the exterior region, consisting of the future and past black hole and cosmological horizons. The uniform decay estimates of the energy are crucial to the construction of the conformal scattering theory
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Coudray, Armand. "Asymptotic behaviour of zero rest-mass fields on radiative space-times". Electronic Thesis or Diss., Brest, 2024. http://www.theses.fr/2024BRES0026.

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Cette thèse explore deux sujets distincts. La première partie examine le comportement asymptotique des ondes scalaires dans l’espace-temps de Vaidya, décrivant un trou blanc sphérique en évaporation via émission de poussières isotropes. L’analyse se focalise sur la régularité des ondes scalaires conformes au bord (passé et futur) isotrope du compactifié, en fonction des données initiales du champ conforme. Nous construisons également l’opérateur de scattering conforme, montrant qu’il encode toute l’évolution du champ dans l’espace-temps compactifié. Ces résultats reposent sur des méthodes d’inégalités d’énergie et de champs de vecteurs. La seconde partie se concentre sur l’analyse des courbes isotropes entrantes dans les espaces-temps purement radiatifs de Robinson-Trautman de type D. Contrairement à une étude précédente sur la métrique de Vaidya, ces courbes ne forment pas l’horizon passé en raison de la géométrie de la solution. Le dernier chapitre classe ces courbes, montrant qu’elles présentent un comportement similaire à celui observé dans l’espace-temps de Vaidya
This thesis adresses two distinct subjects. The first part examines the asymptotic behavior of scalar waves in the Vaidya spacetime, describing a spherical white hole evaporating via emission of isotropic dust. The analysis focuses on the regularity of conformal scalar waves at the isotropic boundary (past and future) of the compactified spacetime, depending on the initial data of the conformal field. Additionally, we construct the conformal scattering operator, demonstrating its ability to encode the entire field evolution in the compactified spacetime.These findings rely on energy inequalities and vector field methods.The second part centers on analyzing incoming isotropic curves in the purely radiative Robinson-Trautman spacetimes of type D. In contrast to a previous study on Vaidya’s metric, these curves do not form the past horizon due to the solution’s geometry. The final chapter categorizes these curves, revealing a behavior akin to that observed in Vaidya’s spacetime
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Pocklington, Andrew Jonathan. "Bulk and boundary scattering in the q-state Potts model". Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4818/.

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This thesis is concerned with the properties of 1 + 1 dimensional massive field theories in both infinite and semi-infinite geometries. Chapters 1, 2 and 3 develop the necessary theoretical framework and review existing work by Chim and Zamolodchikov [1] on integrable perturbations of the (bulk) q-state Potts model, the particular model under consideration in this thesis. Chapter 4 consists of a detailed analysis of the bootstrap for this model, during the course of which unexpected behaviour arises. The treatment of 1] has consequently been revised, but further investigation will be necessary before complete understanding of this behaviour can be reached. In the final chapter, attention turns to the imposition of boundary conditions on two dimensional systems. After looking at this from a statistical mechanical point of view, a brief review of boundary conformal held theory and its integrable perturbations is given. This leads once more to a consideration of the q-state Potts model. After summarising [2], where fixed and free boundary conditions are considered, a third and previously untreated boundary condition is discussed.
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Vouvakis, Marinos N. "A Non-Conformal Domain Decomposition Method for Solving Large Electromagnetic Wave Problems". The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1125498071.

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Schuster, Theodor. "Scattering amplitudes in four- and six-dimensional gauge theories". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/17034.

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Streuamplituden der Quantenchromodynamik (QCD), N = 4 Super-Yang-Mills-Theorie (SYM-Theorie) und der sechsdimensionalen N = (1, 1) SYM-Theorie werden untersucht, mit einem Fokus auf die Symmetrien und Relationen zwischen den Streuamplituden dieser Eichtheorien auf dem Baum-Niveau. Die Baum-Niveau- und Ein-Schleifen-Farbzerlegung beliebiger QCD-Amplituden in primitive Amplituden wird bestimmt und Identitäten hergeleitet, welche den Nullraum unter den primitiven Amplituden aufspannen. Anschließend wird bewiesen, dass alle farbgeordneten Baum-Niveau-Amplituden der masselosen QCD aus der N = 4 SYM-Theorie erhalten werden können. Analytische Formeln für alle für die QCD relevanten N = 4 SYM-Amplituden werden bestimmt und die Effizienz und Genauigkeit der numerischen Auswertung der analytischen Formeln für farbgeordnete QCD-Baum-Niveau-Amplituden mit einer effizienten numerischen Implementierung der Berends-Giele-Rekursion verglichen. Die Symmetrien der massive Amplituden auf dem Coulomb-Zweig der N = 4 SYM-Theorie werden hergeleitet. Diese können durch eine dimensionale Reduktion der masselosen Baum-Niveau-Amplituden der sechsdimensionalen N = (1, 1) SYM-Theory erhalten werden. Darüber hinaus wird bezeigt, wie es mit Hilfe einer numerischen Implementierung der BCFW-Rekursion möglich ist analytische Formeln für die Baum-Niveau-Superamplituden der N = (1, 1) SYM-Theory zu erhalten und die Möglichkeit eines Uplifts der masselose Baum-Niveau-Amplituden der N = 4 SYM-Theory untersucht. Schließlich wird eine Alternative zur dimensionalen Regularisierung der N = 4 SYM-Theorie untersucht. Die Infrarotdivergenzen werden hierbei durch Massen regularisiert, die durch einen Higgs-Mechanismus erhalten wurden. Die korrespondierende Stringtheorie-Beschreibung deutet auf eine exakte duale konforme Symmetrie der Streuamplituden hin. Durch explizite Rechnungen wird dies bestätigt und Vorteile des Regulators werden demonstriert.
We study scattering amplitudes in quantum chromodynamics (QCD), N = 4 super Yang-Mills (SYM) theory and the six-dimensional N = (1, 1) SYM theory, focusing on the symmetries of and relations between the tree-level scattering amplitudes in these three gauge theories. We derive the tree level and one-loop color decomposition of an arbitrary QCD amplitude into primitive amplitudes. Furthermore, we derive identities spanning the null space among the primitive amplitudes. We prove that every color ordered tree amplitude of massless QCD can be obtained from gluon-gluino amplitudes of N = 4 SYM theory. Furthermore, we derive analytical formulae for all gluon-gluino amplitudes relevant for QCD. We compare the numerical efficiency and accuracy of evaluating these closed analytic formulae for color ordered QCD tree amplitudes to a numerically efficient implementation of the Berends-Giele recursion. We derive the symmetries of massive tree amplitudes on the coulomb branch of N = 4 SYM theory, which in turn can be obtained from N = (1, 1) SYM theory by dimensional reduction. Furthermore, we investigate the tree amplitudes of N = (1, 1) SYM theory and explain how analytical formulae can be obtained from a numerical implementation of the supersymmetric BCFW recursion relation and investigate a potential uplift of the massless tree amplitudes of N = 4 SYM theory. Finally we study an alternative to dimensional regularization of N = 4 SYM theory. The infrared divergences are regulated by masses obtained from a Higgs mechanism. The corresponding string theory set-up suggests that the amplitudes have an exact dual conformal symmetry. We confirm this expectation and illustrate the calculational advantages of the massive regulator by explicit calculations.
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Michalet, Xavier. "Étude expérimentale de vésicules phospholipidiques de genre topologique non sphérique". Paris 7, 1994. http://www.theses.fr/1994PA077164.

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Les vésicules phospholipidiques sont constituées de membranes fluides fermées dont la forme d'équilibre est gouvernée par une énergie élastique de courbure. La pertinence de ce modèle est ici étudiée expérimentalement dans le cas des vésicules de genre non sphérique. Les observations montrent la nécessité de prendre en compte les états métastables prévus par la théorie. Des observations de formes d'équilibre de genre torique non prévues par les méthodes standard, sont étudiées grâce à une approche numérique nouvelle, qui confirme la validité du modèle d'énergie élastique de courbure. Des expériences de changement de forme du tore de Clifford illustrent par ailleurs la propriété d'invariance conforme de cette énergie. Cette propriété se traduit en outre pour les vésicules de genre topologique supérieur à 1 par le phénomène de diffusion conforme, qui est ici observé pour la première fois. L'observation de fluctuations thermiques importantes de vésicules de genre topologique élevé, analysée dans le cadre d'un modèle géométrique simple, illustre d'une autre façon la spécificité des vésicules de topologie non sphérique pour le problème des formes d'équilibre
Phospholipidic vesicles are made of fluid, closed membranes. Their equilibrium shapes can be calculated using a curvature elastic energy. The validity of such a the¬oretical description is st udied by comparison with experimental observations of vesi¬cles of non spherical topology. Observations of new stable equilibrium shapes show that metastable shapes predicted theoretically must also be taken into account. Some unpredicted observed shapes are studied using a new numerical approach, which fully confirm the validity of the curvature elasticity model. Shape transfor¬mations experiments of the Clifford torus moreover prove the conformai invariance of the energy. This property lias a striking theoretical consequence for vesicles of topological genus greater than 1, called conformai diffusion, first observed in this study. The observation of strong thermal fluctuation of vesicles of high topological genus, which is analysed using a simple geometrical model, is another novel feature of vesicles of non spherical topology
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Mazzoni, Michele. "Generalized hydrodynamics of a (1+1)-dimensional integrable scattering theory with roaming trajectories". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23209/.

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The emergence of hydrodynamic features in off-equilibrium (1 + 1)-dimensional integrable quantum systems has been the object of increasing attention in recent years. In this Master Thesis, we combine Thermodynamic Bethe Ansatz (TBA) techniques for finite-temperature quantum field theories with the Generalized Hydrodynamics (GHD) picture to provide a theoretical and numerical analysis of Zamolodchikov’s staircase model both at thermal equilibrium and in inhomogeneous generalized Gibbs ensembles. The staircase model is a diagonal (1 + 1)-dimensional integrable scattering theory with the remarkable property of roaming between infinitely many critical points when moving along a renormalization group trajectory. Namely, the finite-temperature dimensionless ground-state energy of the system approaches the central charges of all the minimal unitary conformal field theories (CFTs) M_p as the temperature varies. Within the GHD framework we develop a detailed study of the staircase model’s hydrodynamics and compare its quite surprising features to those displayed by a class of non-diagonal massless models flowing between adjacent points in the M_p series. Finally, employing both TBA and GHD techniques, we generalize to higher-spin local and quasi-local conserved charges the results obtained by B. Doyon and D. Bernard [1] for the steady-state energy current in off-equilibrium conformal field theories.
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Harwood, Adrian Roy George. "Numerical evaluation of acoustic Green's functions". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/numerical-evaluation-of-acoustic-greens-functions(809386ea-59cb-453b-9770-5e3250b35e98).html.

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The reduction of noise generated by new and existing engineering products is of increasing importance commercially, socially and environmentally. Commercially, the noise emission of vehicles, such as cars and aircraft, may often be considered a selling point and the effects of noise pollution on human health and the environment has led to legislation restricting the noise emissions of many engineering products. Noise prediction schemes are important tools to help us understand and develop a means of controlling noise. Acoustic problems present numerous challenges to traditional CFD-type numerical methods rendering all but the most trivial problems unsuitable. Difficulties relate to the length scale discrepancies which arise due to the relatively tiny pressure and density fluctuations of an acoustic wave propagating over large distancesto the point of interest; the result being large computational domains to capture wave behaviour accurately between source and observer. Noise prediction may be performed using a hybrid Computational Aero-Acoustics (CAA) scheme, an approach to noise prediction which alleviates many issues associated with exclusively numerical or analytical approaches. Hybrid schemes often rely on knowledge of a Green’s function, representing the scattering of the geometry, to propagate source fluctuations to the far-field. Presently, these functions only exist in analytical form for relatively simple geometries. This research develops principles for the robust calculation of Green’s functions for general situations. In order to achieve this, three techniques to computeGreen’s functions for the Helmholtz equation within an extended class of 2D geometries are developed, evaluated and compared. Where appropriate, their extension to 3D is described. Guidance is provided on the selection of a suitable numerical method in practice given knowledge of the geometry of interest. Through inclusion of the numerical methods for the construction of Green’s functions presented here, the applicability of existing hybrid schemes will be significantly extended. Thus, it is expected that noise predictions may be performed on a more general range of geometries while exploiting the computational efficiency of hybrid prediction schemes.
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Libri sul tema "Scattering conforme"

1

Kempel, Leo C. Radiation and scattering from cylindrically conformal printed antennas. Ann Arbor, Mich: The University of Michigan, Radiation Laboratory, Dept. of Electrical Engineering and Computer Science, 1994.

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1956-, Volakis John Leonidas, e United States. National Aeronautics and Space Administration., a cura di. Radiation and scattering from cylindrically conformal printed antennas. Ann Arbor, Mich: The University of Michigan, Radiation Laboratory, Dept. of Electrical Engineering and Computer Science, 1994.

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Kempel, Leo C. Radiation and scattering from printed antennas on cylindrically conformal platforms. Ann Arbor, Mich: University of Michigan, Radiation Laboratory, Dept. of Electrical Engineering and Computer Science, 1993.

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Kempel, Leo C. Radiation and scattering from printed antennas on cylindrically conformal platforms. Ann Arbor, Mich: University of Michigan, Radiation Laboratory, Dept. of Electrical Engineering and Computer Science, 1994.

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Kempel, Leo C. Radiation and scattering from printed antennas on cylindrically conformal platforms. Ann Arbor, Mich: University of Michigan, Radiation Laboratory, Dept. of Electrical Engineering and Computer Science, 1994.

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6

Jakobson, Dmitry, Pierre Albin e Frédéric Rochon. Geometric and spectral analysis. Providence, Rhode Island: American Mathematical Society, 2014.

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Steeds, Mark William. A comparison of two conformal methods for FDTD modeling. 1995.

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Dorey, Patrick, Gregory Korchemsky, Nikita Nekrasov, Volker Schomerus, Didina Serban e Leticia Cugliandolo, a cura di. Integrability: From Statistical Systems to Gauge Theory. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198828150.001.0001.

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This volume contains lectures delivered at the Les Houches Summer School ‘Integrability: from statistical systems to gauge theory’ held in June 2016. The School was focussed on applications of integrability to supersymmetric gauge and string theory, a subject of high and increasing interest in the mathematical and theoretical physics communities over the past decade. Relevant background material was also covered, with lecture series introducing the main concepts and techniques relevant to modern approaches to integrability, conformal field theory, scattering amplitudes, and gauge/string duality. The book will be useful not only to those working directly on integrablility in string and guage theories, but also to researchers in related areas of condensed matter physics and statistical mechanics.
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Capitoli di libri sul tema "Scattering conforme"

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Colwell, Kitran Macey M. "Scattering Amplitudes". In Dualities, Helicity Amplitudes, and Little Conformal Symmetry, 47–71. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-67392-9_4.

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Badger, Simon, Johannes Henn, Jan Christoph Plefka e Simone Zoia. "On-Shell Techniques for Tree-Level Amplitudes". In Lecture Notes in Physics, 53–93. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-46987-9_2.

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AbstractIn this chapter we focus on the pole structure of tree-level amplitudes. We argue that amplitudes factorise on these poles into lower-point amplitudes. Moreover, universal factorisation structures emerge when two momenta become collinear as well as in the limit of low energy of a single particle—the soft limit. These factorisation properties are the basis of an efficient technique for computing tree-level scattering amplitudes in gauge theories and gravity recursively—without ever referring to Feynman rules or even a Lagrangian. These recursion relations use as input lower-point amplitudes, so that the gauge redundancy, which is partly responsible for the complexity of conventional Feynman graph calculations, is absent in this entirely on-shell based formalism. We then show the invariance of scattering amplitudes under Poincaré transformations, and introduce the conformal symmetry of gauge-theory tree-level amplitudes. Finally, we highlight a surprising double-copy relation between gluon and graviton amplitudes.
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Yang, Fu-Bao, e Ji-Ping Huang. "Particle Diffusion Process with Artificial Control: Diffusion Metamaterials". In Diffusionics, 297–319. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-0487-3_17.

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AbstractDiffusion acts as a fundamental process for both energy and mass movement, showcasing dynamics that differs from wave propagation. The emergence of metamaterials provides a robust platform for custom manipulations of mass diffusion, drawing on principles like transformation theory and scattering-cancellation theory. Such manipulations have set the stage for novel findings and pioneering applications. This chapter delves into a thorough analysis of the recent progress in diffusion metamaterials. Earlier studies are methodically categorized based on diffusion models, delving deeply into the related theories, applications, finite-element simulations, and experimental approaches of different mechanisms. The chapter wraps up with a scrutiny of the inherent challenges tied to the theoretical underpinnings and architectural design of diffusion metamaterials. Some of these challenges are seen as potentially mitigated by upcoming approaches, such as pseudo-conformal mapping and machine-learning methodologies.
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Kleban, P., R. Hentschke e J. C. Campuzano. "Conformal Invariance, Multiple Scattering and the Au(110) (1×2) to (1×1) Phase Transition". In Kinetics of Interface Reactions, 280–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-72675-0_23.

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Caratelli, D., R. Cicchetti, M. Simeoni e A. Yarovoy. "Accurate Modelling of Ultra-short Electromagnetic Pulse Scattering Using a Locally Conformal Finite-Difference Time-Domain Scheme". In Ultra-Wideband, Short Pulse Electromagnetics 9, 55–63. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-0-387-77845-7_7.

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"Scattering from Conformal Arrays". In Conformal Array Antenna Theory and Design, 421–61. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/047178012x.ch11.

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Tseytlin, A. A. "Scattering Via Conformal Higher Spin Exchanges". In Higher Spin Gauge Theories, 39–50. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789813144101_0004.

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Blackledge, Jonathan. "Perspective Chapter: Simulation and Analysis of Synthetic Aperture Radar Images". In Digital Image Processing - Latest Advances and Applications [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.1002781.

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The principal model for an image, generated by the interaction of an incident wave field with an inhomogeneous medium, is based on the ‘weak scattering approximation’. This approximation forms the basis for image processing, analysis and image understanding associated with applications over a broad range of frequencies. The physical limitations of such a model are typically overcome by introducing an additional stochastic field term that takes into account those effects that do not conform to the weak scattering approximation, coupled with background ‘system noise’. In this chapter, a solution to the scattering problem is presented, which is based on an exact scattering solution. An application of this solution is then considered which focuses on developing a model for a Synthetic Aperture Radar (SAR) image of the earth’s surface. By assuming that the surface is a fractal (a Mandelbrot surface), it is shown how an overhead optical image of the surface may be used to simulate a SAR image. The purpose of this is to generate training data for developing computer vision solutions using machine learning for autonomous navigation using SAR and for target detection in cases where only optical image data are available.
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Mussardo, Giuseppe. "Form Factor Perturbation Theory". In Statistical Field Theory, 863–81. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198788102.003.0022.

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Chapter 22 introduces a perturbative technique based on the form factors to study non-integrable models. These models often include stumbling blocks like decays and production scattering processes, confinement phenomena and nucleation of false vacua, resonance peaks in the cross sections, etc. All these physical aspects are usually accompanied by a great mathematical complexity. However, the perturbative technique permits the computation of the corrections to the mass spectrum, the vacuum energy, the scattering amplitudes and so on. This chapter discusses in depth multiple deformations of the conformal field theories, form factor perturbation theory, first-order perturbation theory, non-locality and confinement of the excitations and the multi-frequency Sine–Gordon model.
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"Asymptotics of Correlation Functions and the Conformal Approach". In Quantum Inverse Scattering Method and Correlation Functions, 502–17. Cambridge University Press, 1993. http://dx.doi.org/10.1017/cbo9780511628832.023.

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Atti di convegni sul tema "Scattering conforme"

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Kisel, Natalia N., e Andrew A. Maksimenko. "Reduction of the Radar Cross Section of Conformed Microstrip Antennas Using Metamaterials". In 2021 Radiation and Scattering of Electromagnetic Waves (RSEMW). IEEE, 2021. http://dx.doi.org/10.1109/rsemw52378.2021.9494146.

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Kumar, Samir, Yusuke Doi, Kyoko Namura e Motofumi Suzuki. "Extended Abstract of the Japan Society of Applied Physics". In JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2019. http://dx.doi.org/10.1364/jsap.2019.18a_e208_4.

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In the past few decades, Raman scattering has gained attention as a spectroscopic technique for the study of chemical and biological sensing, as it is a label-free non-invasive method.[1] However, the main drawback of Raman spectroscopy is the intrinsically low signal intensity, which leads to unsuitably high detection limits. Hence, the exploitation of plasmonics for enhancing Raman signal has become an important factor for the routine application of this technique. Silicon wafers and glass slides are two of the most common substrates used for the growth of SERS active layers.[2] However, these substrates are rigid and brittle, and hence, these static substrates severely limit the application of plasmonic nanostructures. Flexible substrates have an advantage over the conventional rigid substrates because of their ability to conform to the underlying object.[3] They can be wrapped onto curved surfaces and can be easily cut into different shapes and sizes for applications which demand non-planar, flexible or conformal surfaces.[4]
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Fadin, Victor. "Standard and quasi-conformal BFKL kernels". In XXI International Workshop on Deep-Inelastic Scattering and Related Subjects. Trieste, Italy: Sissa Medialab, 2013. http://dx.doi.org/10.22323/1.191.0078.

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Semenikhin, Andrey I., e Diana V. Semenikhina. "Conformal Prismatic Cylindrical Metasurfaces Containing Identical OAM-Modules for RCS Reduction". In 2023 Radiation and Scattering of Electromagnetic Waves (RSEMW). IEEE, 2023. http://dx.doi.org/10.1109/rsemw58451.2023.10202052.

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Jing-cheng, Zhao, Gu Shao-zhu, Yang Tao e Zhang Wu. "A Scattering Measurement Carrier of Conformal Antenna". In the 2017 2nd International Conference. New York, New York, USA: ACM Press, 2017. http://dx.doi.org/10.1145/3158233.3159364.

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Labate, G., L. Matekovits e M. Orefice. "Inverse Scattering Homogenization method for conformal metamaterial structures". In 2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting. IEEE, 2015. http://dx.doi.org/10.1109/aps.2015.7304417.

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Semenikhin, A. I., e A. I. Chernokolpakov. "Radiation Characteristics of the Conformal 4-Port Magnetic Antenna in a Superstructure of the Surface Ship". In 2019 Radiation and Scattering of Electromagnetic Waves (RSEMW). IEEE, 2019. http://dx.doi.org/10.1109/rsemw.2019.8792767.

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Semenikhin, A. I., e A. I. Chernokolpakov. "Active cancellation of radar cross section of large aircraft using conformai 2-port magnetic T-shaped antenna". In 2017 Radiation and Scattering of Electromagnetic Waves (RSEMW). IEEE, 2017. http://dx.doi.org/10.1109/rsemw.2017.8103623.

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Begishev, I. A., I. A. Kulagin e T. Usmanov. "High efficiency Raman amplification of waves with conformed profiles". In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/cleo_europe.1994.cwf85.

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In the case of the scattering Raman amplification of light beams in a field of powerful ultrashort pulses, the back influence of the amplified radiation on the fundamental wave may be significant. Moreover, properties of the media, such as a population of atomic states, may significantly change. That leads to amplitude-phase modulation of the fundamental pulse owing to change of direction of intensity exchange in the pulse.1 As a result, the bond between the fundamental and Stokes waves becomes weaker, that results in a decrease in the frequency conversion efficiency. For spatial inhomogeneous beams this effect is different in various beam sections.
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Sabio Vera, Augustin, e F. Schwennsen. "Conformal Signatures in Mueller-Navelet and Forward Jets in DIS". In Proceedings of the XVI International Workshop on Deep-Inelastic Scattering and Related Topics. Amsterdam: Science Wise Publishing, 2008. http://dx.doi.org/10.3360/dis.2008.75.

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Rapporti di organizzazioni sul tema "Scattering conforme"

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Mei, Kenneth K. Conformal Time Domain Finite Difference Method of Solving Electromagnetic Wave Scattering. Fort Belvoir, VA: Defense Technical Information Center, ottobre 1988. http://dx.doi.org/10.21236/ada200921.

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Reeder, D. B., e Timothy K. Stanton. Acoustic Scattering by Axisymmetric Finite-Length Bodies: An Extension of a 2-Dimensional Conformal Mapping Method. Fort Belvoir, VA: Defense Technical Information Center, ottobre 2002. http://dx.doi.org/10.21236/ada410119.

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