7 papers · 1 filter
"Detuned" f(R) gravity and dark energy
Nathalie Deruelle, Misao Sasaki, Yuuiti Sendouda
In gravity theories derived from a f(R) Lagrangian, matter is usually supposed to be minimally coupled to the metric, which hence defines a ``Jordan frame.'' However, since the fie…
Junction Conditions in f(R) Theories of Gravity
Nathalie Deruelle, Misao Sasaki, Yuuiti Sendouda
Taking advantage of the conformal equivalence of f(R) theories of gravity with General Relativity coupled to a scalar field we generalize the Israel junction conditions for this cl…
Gradient expansion approach to nonlinear superhorizon perturbations II -- a single scalar field --
Yoshiharu Tanaka, Misao Sasaki
We formulate nonlinear perturbations of a scalar field dominated universe on super-horizon scales. We consider the case of a single scalar field. We take the gradient expansion app…
A Brane World in an Arbitrary Number of Dimensions without Z_2 Symmetry
Daisuke Yamauchi, Misao Sasaki
We consider a brane world in an arbitrary number of dimensions without Z_2 symmetry and derive the effective Einstein equation on the brane, where its right-hand side is given by t…
Gradient expansion approach to nonlinear superhorizon perturbations
Yoshiharu Tanaka, Misao Sasaki
Using the gradient expansion approach, we formulate a nonlinear cosmological perturbation theory on super-horizon scales valid to , where is the expansion parameter ass…
Born-Again Braneworld
Sugumi Kanno, Misao Sasaki, Jiro Soda
We propose a cosmological braneworld scenario in which two branes collide and emerge as reborn branes with signs of tensions opposite to the original tensions of respective branes.…