708 citations · 1.7k across the 9 of their papers we have counts for
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What is needed of a tachyon if it is to be the dark energy?
Edmund J. Copeland, Mohammad R. Garousi, M. Sami +1
We study a dark energy scenario in the presence of a tachyon field with potential and a barotropic perfect fluid. The cosmological dynamics crucially depends on the asym…
Chaotic dynamics in preheating after inflation
Yoshida Jin, Shinji Tsujikawa
We study chaotic dynamics in preheating after inflation in which an inflaton is coupled to another scalar field through an interaction . We first estimate t…
A unified approach to scaling solutions in a general cosmological background
Shinji Tsujikawa, M. Sami
Our ignorance about the source of cosmic acceleration has stimulated study of a wide range of models and modifications to gravity. Cosmological scaling solutions in any of these th…
Observational constraints on patch inflation in noncommutative spacetime
Gianluca Calcagni, Shinji Tsujikawa
We study constraints on a number of patch inflationary models in noncommutative spacetime using a compilation of recent high-precision observational data. In particular, the four-d…
Observational constraints on braneworld inflation: the effect of a Gauss-Bonnet term
Shinji Tsujikawa, M. Sami, Roy Maartens
High-energy modifications to general relativity introduce changes to the perturbations generated during inflation, and the latest high-precision cosmological data can be used to pl…
Dilatonic ghost condensate as dark energy
Federico Piazza, Shinji Tsujikawa
We explore a dark energy model with a ghost scalar field in the context of the runaway dilaton scenario in low-energy effective string theory. We address the problem of vacuum stab…