519 research outputs found

    Charged Anti-de Sitter BTZ black holes in Maxwell-f(T)f(T) gravity

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    Inspired by the BTZ formalism, we discuss the Maxwell-f(T)f(T) gravity in (2+1)-dimensions. The main task is to derive exact solutions for a special form of f(T)=T+ϵT2f(T)=T+\epsilon T^2, with TT being the torsion scalar of Weitzenb\ddot{\mbox{o}}ck geometry. To this end, a triad field is applied to the equations of motion of charged f(T)f(T) and sets of circularly symmetric non-charged and charged solutions have been derived. We show that, in the charged case, the monopole-like and the ln{\it ln} terms are linked by a correlative constant despite of known results in teleparallel geometry and its extensions [39]. Furthermore, it is possible to show that the event horizon is not identical with the Cauchy horizon due to such a constant. The singularities and the horizons of these black holes are examined: they are new and have no analogue in literature due to the fact that their curvature singularities are soft. We calculate the energy content of these solutions by using the general vector form of the energy-momentum within the framework of f(T)f(T) gravity. Finally, some thermodynamical quantities, like entropy and Hawking temperature, are derived.Comment: 15 pages, accepted for publication in IJMP

    DD-dimensional charged Anti-de-Sitter black holes in f(T)f(T) gravity

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    We present a DD-dimensional charged Anti-de-Sitter black hole solutions in f(T)f(T) gravity, where f(T)=T+βT2f(T)=T+\beta T^2 and D4D \geq 4. These solutions are characterized by flat or cylindrical horizons. The interesting feature of these solutions is the existence of inseparable electric monopole and quadrupole terms in the potential which share related momenta, in contrast with most of the known charged black hole solutions in General Relativity and its extensions. Furthermore, these solutions have curvature singularities which are milder than those of the known charged black hole solutions in General Relativity and Teleparallel Gravity. This feature can be shown by calculating some invariants of curvature and torsion tensors. Furthermore, we calculate the total energy of these black holes using the energy-momentum tensor. Finally, we show that these charged black hole solutions violate the first law of thermodynamics in agreement with previous results.Comment: 11 Pages, will appear in JHE

    On the energy of charged black holes in generalized dilaton-axion gravity

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    In this paper we calculate the energy distribution of some charged black holes in generalized dilaton-axion gravity. The solutions correspond to charged black holes arising in a Kalb-Ramond-dilaton background and some existing non-rotating black hole solutions are recovered in special cases. We focus our study to asymptotically flat and asymptotically non-flat types of solutions and resort for this purpose to the M{\o}ller prescription. Various aspects of energy are also analyzed.Comment: LaTe

    Teleparallel Energy-Momentum Distribution of Static Axially Symmetric Spacetimes

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    This paper is devoted to discuss the energy-momentum for static axially symmetric spacetimes in the framework of teleparallel theory of gravity. For this purpose, we use the teleparallel versions of Einstein, Landau-Lifshitz, Bergmann and Mo¨\ddot{o}ller prescriptions. A comparison of the results shows that the energy density is different but the momentum turns out to be constant in each prescription. This is exactly similar to the results available in literature using the framework of General Relativity. It is mentioned here that Mo¨\ddot{o}ller energy-momentum distribution is independent of the coupling constant λ\lambda. Finally, we calculate energy-momentum distribution for the Curzon metric, a special case of the above mentioned spacetime.Comment: 14 pages, accepted for publication in Mod. Phys. Lett.

    Cosmological applications in Kaluza-Klein theory

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    The field equations of Kaluza-Klein (KK) theory have been applied in the domain of cosmology. These equations are solved for a flat universe by taking the gravitational and the cosmological constants as a function of time t. We use Taylor's expansion of cosmological function, Λ(t)\Lambda(t), up to the first order of the time tt. The cosmological parameters are calculated and some cosmological problems are discussed.Comment: 14 pages Latex, 5 figures, one table. arXiv admin note: text overlap with arXiv:gr-qc/9805018 and arXiv:astro-ph/980526

    Teleparallel Energy-Momentum Distribution of Spatially Homogeneous Rotating Spacetimes

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    The energy-momentum distribution of spatially homogeneous rotating spacetimes in the context of teleparallel theory of gravity is investigated. For this purpose, we use the teleparallel version of Moller prescription. It is found that the components of energy-momentum density are finite and well-defined but are different from General Relativity. However, the energy-momentum density components become the same in both theories under certain assumptions. We also analyse these quantities for some special solutions of the spatially homogeneous rotating spacetimes.Comment: 12 pages, accepted for publication in Int. J. Theor. Phy

    Pinning Susceptibility: The Effect Of Dilute, Quenched Disorder On Jamming

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    We study the effect of dilute pinning on the jamming transition. Pinning reduces the average contact number needed to jam unpinned particles and shifts the jamming threshold to lower densities, leading to a pinning susceptibility, χp. Our main results are that this susceptibility obeys scaling form and diverges in the thermodynamic limit as χp∝|ϕ−ϕ∞c|−γp where ϕ∞c is the jamming threshold in the absence of pins. Finite-size scaling arguments yield these values with associated statistical (systematic) errors γp=1.018±0.026(0.291) in d=2 and γp=1.534±0.120(0.822) in d=3. Logarithmic corrections raise the exponent in d=2 to close to the d=3 value, although the systematic errors are very large
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