Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 5 of 5 for “"Extended theories of gravity"”.
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THE COVARIANT APPROACH TO SPACE TIMES ANDSOME EXTENDED THEORIES OF GRAVITY
The thesis deals with the covariant description of the geometry of some fundamental spacetimes and their realizations in two recent extensions of GR: Cotton and conformal Killing gravity. In Generalized Robertson - Walker spacetimes the Ricci tensor is the sum of a perfect fluid term and an …
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Stability and gravitational collapse in extended theories of gravity: from singularities to bouncing scenarios
Einstein theory of General Relativity was well adapted and accepted until limitations in the form of an unexplained form of energy, referred today as Dark Energy, were observed. For this reason, modifications to the standard Theory of General Relativity were proposed: the so-called f(R) theories. …
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Evolution of matter density perturbations in viable f (R) theories of gravity
… ΛCDM model, the late-time accelerated expansion of the Universe is explained via a dark energy fluid in the form of a cosmological constant. Such a cosmological constant dominates the energy budget of the Universe today, and yet, it is still a poorly understood species because it is not observed …
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Probing the cosmological dynamics of a logarithmic f (R) theory of gravity
In this thesis we make a contribution in the area of Extended Theories of Gravity (ETG) by studying the dynamics of the R ln R model. We draw attention to the importance of introducing complete alternative theories of gravity and studying the possible geometrical origin of Dark Energy (unknown form …
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Alternative theories of gravity and their application to cosmology
In this thesis we study extended theories of gravity in the context of cosmology. The first part is dedicated to the application of the theory of dynamical systems, which allow us to investigate the global dynamics of some cosmological models resulting from scalar-tensor and higher-order theories …