Cosmological scaling solutions in generalised Gauss-Bonnet gravity theories (2009)
Uddin, Kotub, Lidsey, James E., Tavakol, Reza
The conditions for the existence and stability of cosmological power-law scaling solutions are established when the Einstein-Hilbert action is modified by the inclusion of a function of the...
Constraints on scalar-tensor models of dark energy from observational and local gravity tests (2008)
Tsujikawa, Shinji, Uddin, Kotub, Mizuno, Shuntaro, Tavakol, Reza, Yokoyama, Jun'ichi
We construct a family of viable scalar-tensor models of dark energy (DE) which possess a phase of late-time acceleration preceded by a standard matter era, while at the same time satisfying the local...
Density perturbations in f(R) gravity theories in metric and Palatini formalisms (2007)
Tsujikawa, Shinji, Uddin, Kotub, Tavakol, Reza
We make a detailed study of matter density perturbations in both metric and Palatini formalisms in theories whose Lagrangian density is a general function, f(R), of the Ricci scalar. We derive these...
Cosmological perturbations in Palatini modified gravity (2007)
Uddin, Kotub, Lidsey, James E, Tavakol, Reza
Two approaches to the study of cosmological density perturbations in modified theories of Palatini gravity have recently been discussed. These utilise, respectively, a generalisation of Birkhoff's...