Modified Kantowski-Sachs cosmologies from coset models
نویسندگان
چکیده
منابع مشابه
Kantowski-Sachs String Cosmologies
We present new exact solutions of the low-energy-effective-action string equations with both dilaton φ and axion H fields non-zero. The background universe is of Kantowski-Sachs type. We consider the possibility of a pseudoscalar axion field h (H = eφ(dh)∗) that can be either time or space dependent. The case of time-dependent h reduces to that of a stiff perfect-fluid cosmology. For space-depe...
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Using s-wave and large N approximation the one-loop effective action for 2d dilaton coupled scalars and spinors which are obtained by spherical reduction of 4d minimal matter is found. Quantum effective equations for reduced Einstein gravity are written. Their analytical solutions corresponding to 4d Kantowski-Sachs (KS) Universe are presented. For quantum-corrected Einstein gravity we get non-...
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A numerical integration is made, starting with a Kantowski-Sachs (KS) model with an added initial perturbation at time one-tenth the age of the universe, and evolving up to the present. According to a prediction by Barrow (1989), the ratio between the fluctuations of the average matter density and those of the metric tensor varies with the inverse squared wavelength of the fluctuation. In this ...
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We extend the ideas introduced in the previous work to a more general space-time. In particular we consider the Kantowski-Sachs space time with space section with topology R× S. In this way we want to study a general space time that we think to be the space time inside the horizon of a black hole. In this case the phase space is four dimensional and we simply apply the quantization procedure su...
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ژورنال
عنوان ژورنال: Physics Letters B
سال: 1997
ISSN: 0370-2693
DOI: 10.1016/s0370-2693(97)00712-0