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Chamseddine A.H.,American University of Beirut | Chamseddine A.H.,University of Tours | Chamseddine A.H.,Loire Valley Institute for Advanced Studies | Volkov M.S.,University of Tours
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We present solutions describing spatially closed, open, or flat cosmologies in the massive gravity theory within the recently proposed tetrad formulation. We find that the effect of the graviton mass is equivalent to introducing to the Einstein equations a matter source that can consist of several different matter types - a cosmological term, quintessence, gas of cosmic strings, and non-relativistic cold matter. © 2011 Elsevier B.V.

Gherardi F.,Loire Valley Institute for Advanced Studies | Gherardi F.,Bureau de Recherches Geologiques et Minieres | Audigane P.,Bureau de Recherches Geologiques et Minieres
Greenhouse Gases: Science and Technology | Year: 2013

We present numerical simulations of isothermal reactive flow which might be induced by fluid migration at the caprock-cement interface of an idealized abandoned well in an area considered for geological sequestration of CO 2 in the Paris Basin, France. The calculations are aimed at identifying the mineralogical transformations likely occurring in the cement during the working life and after the closure of the wells present in the area, before the injection of CO2. Field evidence, experimental data, and previous numerical simulations have been used to constrain the initial geochemical conditions and the hydraulic parameters of the model. Significant mineralogical transformations in the cement (portlandite and katoite dissolution, CSH, ettringite, hydrotalcite precipitation), and minor modifications of the initial clayrock mineralogical assemblage (quartz, montmorillonite and illite dissolution, and precipitation of cement-like phases) are predicted at the caprock-cement interface. Associated with these mineralogical transformations, measurable variations in porosity are also computed. Although Portland cement is predicted to retain its integrity at some distance from the interface, calculations confirm the general view that material alteration at the interfaces is of major concern for the minimization of the risks of CO2 leakage from storage zones. Numerical outputs are sensitive with respect to poorly constrained physical and transport parameters, such as the spatial distribution of interconnected porosity in the cement. Different degrees of portlandite dissolution/carbonate precipitation can be predicted during in situ ageing under conditions similar to the Paris Basin, depending on the adopted gridding scheme, i.e. on the conceptualization of the cement as a homogeneous or dual-porosity medium. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd.

Chamseddine A.H.,American University of Beirut | Chamseddine A.H.,University of Tours | Chamseddine A.H.,Loire Valley Institute for Advanced Studies | Mukhanov V.,Ludwig Maximilians University of Munich | Mukhanov V.,New York University
Journal of High Energy Physics | Year: 2011

We present a simplified formulation of massive gravity where the Higgs fields have quadratic kinetic term. This new formulation allows us to prove in a very explicit way that all massive gravity theories considered so far inevitably have Boulware-Deser ghost in non-trivial fluctuations of background metric. © 2011 SISSA.

Cvetic M.,University of Pennsylvania | Cvetic M.,University of Maribor | Gibbons G.W.,University of Cambridge | Gibbons G.W.,University of Tours | And 3 more authors.
Physical Review Letters | Year: 2015

We study the thermodynamical properties of a class of asymptotically conical geometries known as "subtracted geometries." We derive the mass and angular momentum from the regulated Komar integral and the Hawking-Horowitz prescription and show that they are equivalent. By deriving the asymptotic charges, we show that the Smarr formula and the first law of thermodynamics hold. We also propose an analog of Christodulou-Ruffini inequality. The analysis can be generalized to other asymptotically conical geometries. © 2015 American Physical Society.

Duval C.,Aix - Marseille University | Duval C.,University of Toulon | Gibbons G.W.,University of Cambridge | Gibbons G.W.,University of Tours | And 2 more authors.
Classical and Quantum Gravity | Year: 2014

The Bondi-Metzner-Sachs group is shown to be the conformal extension of Lévy-Leblond's 'Carroll' group. Further extension to the Newman-Unti group is also discussed in the Carroll framework. © 2014 IOP Publishing Ltd.

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