5,962 research outputs found

    Existence of global strong solutions in critical spaces for barotropic viscous fluids

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    This paper is dedicated to the study of viscous compressible barotropic fluids in dimension N2N\geq2. We address the question of the global existence of strong solutions for initial data close from a constant state having critical Besov regularity. In a first time, this article show the recent results of \cite{CD} and \cite{CMZ} with a new proof. Our result relies on a new a priori estimate for the velocity, where we introduce a new structure to \textit{kill} the coupling between the density and the velocity as in \cite{H2}. We study so a new variable that we call effective velocity. In a second time we improve the results of \cite{CD} and \cite{CMZ} by adding some regularity on the initial data in particular ρ0\rho_{0} is in H1H^{1}. In this case we obtain global strong solutions for a class of large initial data on the density and the velocity which in particular improve the results of D. Hoff in \cite{5H4}. We conclude by generalizing these results for general viscosity coefficients

    Braneworlds scenarios in a gravity model with higher order spatial three-curvature terms

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    In this work we study a Horava-like five-dimensional model in the context of braneworld theory. To begin with, the equations of motion of such model are obtained and, within the realm of warped geometry, we show that the model is consistent if and only if λ\lambda takes its relativistic value 1. Furthermore, since the first derivative of the warp factor is discontinuous over the branes, we show that the elimination of problematic terms involving the square of the warp factor second order derivatives are eliminated by imposing detailed balance condition in the bulk. Afterwards, the Israel's junction conditions are computed, allowing the attainment of an effective Lagrangian in the visible brane. In particular, for a (4+1)-dimensional Horava-like model defined in the bulk without cosmological constant, we show that the resultant effective Lagrangian in the brane corresponds to a (3+1)-dimensional Horava-like model with an emergent positive cosmological constant but without detailed balance condition. Now, restoration of detailed balance condition, at this time imposed over the brane, plays an interesting role by fitting accordingly the sign of the arbitrary constant β\beta that labels the extra terms in the model, insuring a positive brane tension and a real energy for the graviton within its dispersion relation. To end up with, the brane consistency equations are obtained and, as a result, we show that the detailed balance condition again plays an essential role in eliminating bad behaving terms and that the model admits positive brane tensions in the compactification scheme if, and only if, β\beta is negative, what is in accordance with the previous result obtained for the visible brane.Comment: 23 pages, 1 figure, title modifie

    Solution for a local straight cosmic string in the braneworld gravity

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    In this work we deal with the spacetime shaped by a straight cosmic string, emerging from local gauge theories, in the braneworld gravity context. We search for physical consequences of string features due to the modified gravitational scenario encoded in the projected gravitational equations. It is shown that cosmic strings in braneworld gravity may present significant differences when compared to the general relativity predictions since its linear density is modified and the deficit angle produced by the cosmic string is attenuated. Furthermore, the existence of cosmic strings in that scenario requires a strong restriction to the braneworld tension: λ3×1017\lambda \geq 3 \times 10^{-17}, in Planck units.Comment: 7 pages, 3 figure

    Static Domain Wall in the Braneworld gravity

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    In this paper we consider a static domain wall inside a 3-brane. Differently of the standard achievement obtained in General Relativity, the analysis performed here gives a consistency condition for the existence of static domain walls in a braneworld gravitational scenario. It is also shown the behavior of the domain wall gravitational field in the newtonian limit.Comment: 11 pages, no figures, accepted for publication in EPJ

    Constraining Elko Dark Matter at the LHC with Monophoton Events

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    A mass dimension one fermion, also known as Elko, constitutes a dark matter candidate which might interact with photons at the tree level in a specific fashion. In this work, we investigate the constraints imposed by unitarity and LHC data on this type of interactions using the search for new physics in monophoton events. We found that Elkos which can explain the dark matter relic abundance mainly through electromagnetic interactions are excluded at the 95\%CL by the 8 TeV LHC data for masses up to 1 TeV.Comment: 6 pages, 4 figure

    Proton endor study of the photoexcited triplet state PT in Rps. sphaeroides R-26 photosynthetic reaction centres

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    The photoexcited triplet state PT of Rhodopseudomonas sphaeroides R-26 has been investigated by ENDOR measurements performed on frozen photosynthetic reaction centre solutions. For the first time hyperfine data could be obtained for PT. These data indicate a delocalisation of the triplet state over two bacteriochlorophyll a molecules
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