Dark energy and cosmological solutions in second-order string gravity

By Gianluca Calcagni, S. Tsujikawa, M. Sami. 2005

152 citations recorded by the source corpus.

We study the cosmological evolution based on a D-dimensional action in low-energy effective string theory in the presence of second-order curvature corrections and a modulus scalar field (a dilaton or compactification modulus). A barotropic perfect fluid coupled to the scalar field is also allowed. Phase space analysis and the stability of asymptotic solutions are performed for a number of models which include (i) a fixed scalar field, (ii) a linear dilaton in the string frame, and (iii) a logarithmic modulus in the Einstein frame. We confront analytical solutions with observational constraints for the deceleration parameter and show that Gauss–Bonnet gravity alone (i.e., with no matter fields) may not explain the current acceleration of the universe. We also study the future evolution of the universe using the Gauss–Bonnet parametrization and find that big rip singularities can be avoided even in the presence of a phantom fluid because of the balance between the fluid and curvature corrections. A non-minimal coupling between the fluid and the modulus field also opens up the interesting possibility of avoiding a big rip regardless of the details of the fluid equation of state.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/99c6e9c9370e43320ef7377ee6a7adeaff16b647

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Citations in the corpus

Modified Gravity and Cosmology (2011, methodology): “The asymptotic behaviour of theories with quadratic corrections to the Einstein-Hilbert were studied, in the context of string cosmology, in [1090, 236, 1218].”
f(R) Theories (2010, background): “Theories with the more general Lagrangian density R/2+ f(R,P1, P2) have been studied by many people in connection to the dark energy problem [142, 110, 521, 420, 585, 64, 166, 543, 180].”