1,907 research outputs found

    Boundary Conformal Anomalies on Hyperbolic Spaces and Euclidean Balls

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    We compute conformal anomalies for conformal field theories with free conformal scalars and massless spin 1/21/2 fields in hyperbolic space Hd\mathbb{H}^d and in the ball Bd\mathbb{B}^d, for 2≤d≤72\leq d\leq 7. These spaces are related by a conformal transformation. In even dimensional spaces, the conformal anomalies on H2n\mathbb{H}^{2n} and B2n\mathbb{B}^{2n} are shown to be identical. In odd dimensional spaces, the conformal anomaly on B2n+1\mathbb{B}^{2n+1} comes from a boundary contribution, which exactly coincides with that of H2n+1\mathbb{H}^{2n+1} provided one identifies the UV short-distance cutoff on B2n+1\mathbb{B}^{2n+1} with the inverse large distance IR cutoff on H2n+1\mathbb{H}^{2n+1}, just as prescribed by the conformal map. As an application, we determine, for the first time, the conformal anomaly coefficients multiplying the Euler characteristic of the boundary for scalars and half-spin fields with various boundary conditions in d=5d=5 and d=7d=7.Comment: 16 pages. V3: small correction

    Operator Mixing in Large NN Superconformal Field Theories on S4\mathbb{S}^4 and Correlators with Wilson loops

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    We find a general formula for the operator mixing on the S4\mathbb{S}^4 of chiral primary operators (CPO) for the N=4{\cal N}=4 theory at large NN in terms of Chebyshev polynomials. As an application, we compute the correlator of a CPO and a Wilson loop, reproducing an earlier result by Giombi and Pestun obtained from a two-matrix model proposal. Finally, we discuss a simple method to obtain correlators in general N=2{\cal N}=2 superconformal field theories in perturbation theory in terms of correlators of the N=4{\cal N}=4 theory.Comment: 15 pages, no figure

    A limit for large RR-charge correlators in N=2\mathcal{N}=2 theories

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    Using supersymmetric localization, we study the sector of chiral primary operators (Tr ϕ2)n({\rm Tr} \, \phi^2 )^n with large RR-charge 4n4n in N=2\mathcal{N}=2 four-dimensional superconformal theories in the weak coupling regime g→0g\rightarrow 0, where λ≡g2n\lambda\equiv g^2n is kept fixed as n→∞n\to\infty , gg representing the gauge theory coupling(s). In this limit, correlation functions G2nG_{2n} of these operators behave in a simple way, with an asymptotic behavior of the form G2n≈F∞(λ)(λ2πe)2n nαG_{2n}\approx F_{\infty}(\lambda) \left(\frac{\lambda}{2\pi e}\right)^{2n}\ n^\alpha , modulo O(1/n)O(1/n) corrections, with α=12dim(g)\alpha=\frac{1}{2} \mathrm{dim}(\mathfrak{g}) for a gauge algebra g\mathfrak{g} and a universal function F∞(λ)F_{\infty}(\lambda). As a by-product we find several new formulas both for the partition function as well as for perturbative correlators in N=2{\cal N}=2 su(N)\mathfrak{su}(N) gauge theory with 2N2N fundamental hypermultiplets

    Cross sections for production of closed superstrings at high energy colliders in brane world models

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    In brane world string models with large extra dimensions, there are processes where fermion and antifermion (or two gluons) can annihilate producing a light particle (e.g. gluon) carrying transverse momentum and a Kaluza-Klein graviton or an excited closed string that propagates in the extra dimensions. In high energy colliders, this process gives a missing momentum signature. We compute the total cross section for this process within the context of type II superstring theory in the presence of a D brane. This includes all missing energy sources for this string theory model up to s=8M_s^2, and it can be used to put new limits on the string scale M_s.Comment: 18 pages, 3 figures. Reference adde

    Il Sistema di Gestione di un Laboratorio di Ricerca & Sviluppo - il caso Compolab

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    In questa tesi viene descritto il lavoro svolto durante l’attività di tirocinio presso il laboratorio COMPOLAB, azienda che si occupa di validazione virtuale ed innovazione di prodotto e processi industriali. L’elaborato inizia con una breve descrizione dell’azienda. Vengono poi illustrati il sistema di gestione delle informazioni, il sistema di gestione dei progetti, il sistema di rilevazione del lavoro svolto in azienda, il foglio di lavoro per il bilancio di progetto e il piano della qualità del laboratorio. Per ogni elemento vengono chiarite le problematiche iniziali e le esigenze dell’azienda, per proseguire con la descrizione della metodologia di lavoro, delle soluzioni adottate e dei risultati ottenuti. Infine vengono tratte le conclusioni sull’impatto che il lavoro svolto ha avuto sull’azienda e gli sviluppi futuri previsti per il sistema di gestione

    Characterization of long period gratings manufactured with fiber optic fusion splicer for sensor development

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    A Long Period Grating (LPG) is a structure inscribed in an optical fiber that is of great interest in the field of communications and sensors. At Centro de Investigaciones Ópticas (CIOp), an LPG manufacturing process was implemented. It is based on use of electric arcs produced with an optical fiber splicer to generate a series of physical disturbances that modify optical fiber behavior as a light transmission guide. Since transmission response of LPG is sensitive to fiber environment conditions, it can be used to detect changes in certain physical and chemical parameters. In particular, it enables the implementation of optical sensors sensitive to temperature, surrounding medium refractive index and axial deformation. Characterization of locally generated LPGs is essential for future design of sensors applicable in many engineering areas. In this article, typical LPG sensitivities to the three mentioned parameters are reportedFil: Alustiza, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentina. Universidad Tecnológica Nacional. Facultad Regional La Plata. Departamento de Ciencias Básicas; ArgentinaFil: Mineo, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Russo, Nelida Araceli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentin
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