11,651 research outputs found

    Minimum Bias and Early QCD at ATLAS

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    The early minimum bias and the QCD results from the ATLAS experiment in the LHC are presented.Comment: 6 pages,8 figures, proceedings for Hadron Collider Physics Symposium, 201

    Spinning Test Particle in Kalb-Ramond background

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    In this work we explore the geodesic deviations of spinning test particles in a string inspired Einstein-Kalb Ramond background. Such a background is known to be equivalent to a spacetime geometry with torsion. We have shown here that the antisymmetric Kalb-Ramond field has significant effect on the geodesic deviation of a spinning test particle. A search for an observational evidence of such an effect in astrophysical experiments may lead to a better undestanding of the geometry of the background spacetime.Comment: 14 pages, Latex, 5 figure

    Wormholes in spacetime with torsion

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    Analytical wormhole solutions in U4U_4 theory are presented. It is discussed whether the extremely short range repulsive forces, related to the spin angular momentum of matter, could be the ``carrier'' of the exoticity that threads the wormhole throat.Comment: 10 pages revte

    Interaction of D-string with F-string: A Path-Integral Formalism

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    A path integral formalism is developed to study the interaction of an arbitrary curved Dirichlet (D-) string with elementary excitations of the fundumental (F-) string in bosonic string theory. Up to the next to leading order in the derivative expansion, we construct the properly renormalized vertex operator, which generalizes the one previously obtained for a D-particle moving along a curved trajectory. Using this vertex, an attempt is further made to quantize the D-string coordinates and to compute the quantum amplitude for scattering between elementary excitations of the D- and F-strings. By studying the dependence on the Liouville mode for the D-string, it is found that the vertex in our approximation consists of an infinite tower of local vertex operators which are conformally invariant on their respective mass-shell. This analysis indicates that, unlike the D-particle case, an off-shell extension of the interaction vertex would be necessary to compute the full amplitude and that the realization of symmetry can be quite non-trivial when the dual extended objects are simultaneously present. Possible future directions are suggested.Comment: 23 pages, latex, no figure

    Stable two--brane models with bulk tachyon matter

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    We explore the possibility of constructing stable, warped two--brane models which solve the hierarchy problem, with a bulk non--canonical scalar field (tachyon matter) as the source term in the action. Among our examples are two models--one with a warp factor (denoted as e−2f(σ)e^{-2f(\sigma)}) which differs from that of the standard Randall--Sundrum by the addition of a quadratic piece in the f(σ)f(\sigma) and another, where the warping is super-exponential. We investigate the issue of resolution of hierarchy and perform a stability analysis by obtaining the effective inter-brane potentials, in each case. Our analysis reveals that there does exist stable values of the modulus consistent with hierarchy resolution in both the models. Thus, these models, in which the bulk scalar field generates the geometry and also ensures stability, provide viable alternatives to the standard Randall--Sundrum two-brane scenario.Comment: Final version published in Int. Jr. Mod. Phys

    Three-dimensional microstructuring of yttrium aluminum garnet crystals for laser active optofluidic applications

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    The following article appeared in Applied Physics Letters 103.4 (2013): 041101 and may be found at http://scitation.aip.org/content/aip/journal/apl/103/4/10.1063/1.4816338We demonstrate three-dimensional microstructuring in a neodymium doped yttrium aluminum garnet (Nd:YAG) crystal. Spatially well-defined hollow microstructures deeply embedded within the material are shown to result from the creation of a pre-damage state within the Nd:YAG crystal network that is validated using luminescence and Raman analyses of the structures. This opens up the potential of fabricating next-generation optofluidic devices in optical gain materialsFinancial support from the Spanish Ministerio de Educación under the Programa de Movilidad de Recursos Humanos del Plan Nacional de IþDþi 2008/2011 for abroad postdoctoral researchers. This work was also supported by the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (Project S2009/MAT- 1756) and by the Spanish Ministerio de Educación y Ciencia (MAT2010-16161

    Studies on fish epidemics from Assam

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    Investigations conducted since July 1988 on ulcerative fish epidemics in Assam, India, indicated that mainly four species of fishes belonging to the genera Puntius, Channa, Macrognathus and Mystus were widely affected by the disease. Results indicated that outbreak of the disease may not be due to organic pollution of water or radioactive and heavy-metallic contamination. Bacterial culture revealed colonies of Escherichia coli and Pseudomonas aeruginosa in the surface muscular lesions and gill tissues while preliminary electron microscopic studies indicated the presence of viruses in the muscles and gills of diseased fishes
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