Yazar "Keskin, A. I." seçeneğine göre listele

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    Öğe
    SPIN-1/2 PARTICLES IN TORSION GRAVITY WHEN A CONSTANT ELECTRIC FIELD IS PRESENT
    (Editura Acad Romane, 2013) Keskin, A. I.; Binbay, F.; Salti, M.; Acikgoz, I.
    In this work, we focus on the dynamics of Dirac particles in the presence of a constant electric field in a cosmological anisotropic universe. Instead of Einstein's theory of general relativity, we perform the calculations using the teleparallel theory of gravity which is also called as the torsion gravity. First, we found the exact solution of the teleparallel Dirac equation in an anisotropic Bianchi-I universe. Second, the harmonic oscillator behaviour of the solution and then the quantization of oscillation frequency had been discussed. Third, we investigated the spin precession of Dirac particles and dispute the axial-vector spin coupling term.
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    Öğe
    Unified solutions of extended Gauss-Bonnet gravity
    (Springer, 2016) Keskin, A. I.; Acikgoz, I.
    We study some scale factor power-law solutions of the field equations of the extended Gauss Bonnet gravity in the spatial FRW (Friedmann-Robertson-Walker) universe. We consider the lagrangian density given by F(R, G) = f (G) + R + alpha R-2 which exhibits a modification comparing with the modified Gauss Bonnet gravity. After constructing the Friedmann equations and finding the power-law solution we obtain the real valued of our model describing a mechanism that shows transitions among three stages of the universe (inflation, deceleration, acceleration) in an unified way. In particular, in this unified solution we obtained an inflation model without using any scalar field description when alpha > 0, and also we verified our early time inflationary scenario using observational parameters, i.e. n(s), r. Further, we research for the power-law solution of our model when the universe is in the phantom phase. Here, it is observed that the acceleration of the universe in phantom region is composed of two phases which congruent with the recent observations.