8,413 research outputs found

    Thermodynamics of an Evaporating Schwarzschild Black Hole in Noncommutative Space

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    We investigate the effects of space noncommutativity and the generalized uncertainty principle on the thermodynamics of a radiating Schwarzschild black hole. We show that evaporation process is in such a way that black hole reaches to a maximum temperature before its final stage of evolution and then cools down to a nonsingular remnant with zero temperature and entropy. We compare our results with more reliable results of string theory. This comparison Shows that GUP and space noncommutativity are similar concepts at least from view point of black hole thermodynamics.Comment: 15 Pages, 2 Figures, revised and refernces adde

    Soil-gas geochemistry as permeability tracer of thermally altered clays at Orciatico (Tuscany, Central Italy)

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    The physical properties of clay allow to consider argillaceous formations as geological barriers to radionuclide migration in high-level radioactive-waste isolation systems. As laboratory simulations are short term and numerical models always involve assumptions and simplifications of the natural system, natural analogues are extremely attractive surrogates for the study of long-term isolation. The thermally altered clays of the Orciatico area (Tuscany, Central Italy) represent an interesting natural model of a heat source which acted on argillaceous materials. The study of this natural analogue was performed through detailed geoelectrical and soil-gas surveys in order to define both the geometry of the intrusive body and the gas permeability of a clay unit characterized by different thermal alteration degrees. In particular, soil-gas radon and carbon dioxide distributions highlighted that the clay sequences, in spite of their thickness and plasticity, if fractured and metamorphosed, form a lesser impermeable barrier for naturally migrating gas

    On Black Holes and Cosmological Constant in Noncommutative Gauge Theory of Gravity

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    Deformed Reissner-Nordstr\"om, as well as Reissner-Nordstr\"om de Sitter, solutions are obtained in a noncommutative gauge theory of gravitation. The gauge potentials (tetrad fields) and the components of deformed metric are calculated to second order in the noncommutativity parameter. The solutions reduce to the deformed Schwarzschild ones when the electric charge of the gravitational source and the cosmological constant vanish. Corrections to the thermodynamical quantities of the corresponding black holes and to the radii of different horizons have been determined. All the independent invariants, such as the Ricci scalar and the so-called Kretschmann scalar, have the same singularity structure as the ones of the usual undeformed case and no smearing of singularities occurs. The possibility of such a smearing is discussed. In the noncommutative case we have a local disturbance of the geometry around the source, although asymptotically at large distances it becomes flat.Comment: Based on a talk given at the International Conference on Fundamental and Applied Research in Physics "Farphys 2007", 25-28 October 2007, Iasi, Romani

    Energy scales in a stabilized brane world

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    Brane world gravity looks different for observers on positive and negative tension branes. First we consider the well-known RS1 model with two branes embedded into the AdS_5 space-time and recall the results on the relations between the energy scales for an observer on the negative tension brane, which is supposed to be "our" brane. Then from the point of view of this observer we study energy scales and masses for the radion and graviton excitations in a stabilized brane world model. We argue that there may be several possibilities leading to scales of the order 1-10 TeV or even less for new physics effects on our brane. In particular, an interesting scenario can arise in the case of a "symmetric" brane world with a nontrivial warp factor in the bulk, which however takes equal values on both branes.Comment: 15 pages, corrected typos, enlarged conten

    Discriminating graviton exchange effects from other new physics scenarios in e^+e^- collisions

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    We study the possibility of uniquely identifying the effects of graviton exchange from other new physics in high energy e^+e^- annihilation into fermion-pairs. For this purpose, we use as basic observable a specific asymmetry among integrated differential distributions, that seems particularly suitable to directly test for such gravitational effects in the data analysis.Comment: 18 pages, including figures; v2: additional references and acknowledgements. To appear in PR

    Gravity and Matter in Extra Dimensions

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    In this paper, we derive from the viewpoint of the effective 4D theory the interaction terms between linearized gravity propagating in N>= 2 large extra dimensions and matter propagating into one extra dimension. This generalizes known results for the interactions between gravity and 4D matter in ADD-type models. Although we assume that matter is described by an Universal Extra Dimensions (UED) scenario (with all fields propagating into the fifth dimension), we present our results in a general form that can be easily adapted to various other scenarios of matter distribution. We then apply our results to the UED model on a fat brane and consider some phenomenological applications. Among these are the computation of the gravitational decay widths of the matter KK excitations and the effect the width of the brane has on the interactions of gravity with Standard Model particles. We also estimate the cross-section for producing single KK excitations at colliders through KK number-violating gravitational interaction.Comment: 21 pages, 6 figures, Late

    Biosensing platform combining label-free and labelled analysis using Bloch surface waves

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    Bloch surface waves (BSW) propagating at the boundary of truncated photonic crystals (1D-PC) have emerged as an attractive approach for label-free sensing in plasmon-like sensor configurations. Due to the very low losses in such dielectric thin film stacks, BSW feature very low angular resonance widths compared to the surface plasmon resonance (SPR) case. Besides label-free operation, the large field enhancement and the absence of quenching allow utilizing BSW coupled fluorescence detection to additionally sense the presence of fluorescent labels. This approach can be adapted to the case of angularly resolved resonance detection, thus giving rise to a combined label-free / labelled biosensor platform. It features a parallel analysis of multiple spots arranged as a one-dimensional array inside a microfluidic channel of a disposable chip. Application of such a combined biosensing approach to the detection of the Angiopoietin-2 cancer biomarker in buffer solutions is reported

    b→sγb \to s \gamma decays in the Left-Right Symmetric Model

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    We consider b→sγb \to s \gamma decays in the Left-Right Symmetric Model. Values of observables sensitive to chiral structure such as the Λ\Lambda polarization in the Λb→Λγ\Lambda_b \to \Lambda \gamma decays and the mixing-induced CP asymmetries in the Bd,s→M0γB_{d,s} \to M^0 \gamma decays can deviate in the LRSM significantly from the SM values. The combined analysis of PΛP_\Lambda and ACPA_{CP} as well as BR(b→sγ){\cal BR}(b \to s \gamma) can be used to determine the model parameters.Comment: 16 pages with 7 figures, Version to be published in PR
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