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Using the covariant approach and conformal transformations, we present a gauge-invariant formalism for cosmological perturbations in generalized Einstein theories (GETs), including the Brans-Dicke theory, theories with a non-minimally coupled scalar field and certain curvature-squared theories. We find an enhancement in the growth rate of density… (More)

- Seiji Kawamura, Masaki Ando, +131 authors Taizoh Yoshino
- 2008

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. The goal of DECIGO is to detect gravitational waves from various kinds of sources mainly between 0.1 Hz and 10 Hz and thus to open a new window of observation for gravitational wave astronomy. DECIGO will consist of three dragfree… (More)

We study the dynamics of topological defects in the context of “topological inflation” proposed by Vilenkin and Linde independently. Analysing the time evolution of planar domain walls and of global monopoles, we find that the defects undergo inflationary expansion if η > ∼ 0.33mP l, where η is the vacuum expectation value of the Higgs field and mP l is the… (More)

Recent progress in a superstring theory shows that different string theories are connected with each other via dualities, making them to be unified to the M theory in 11 dimensions [1]. This provides us a motivation to study a higher dimensional gravitational theory. String theory also predicts a boundary layer, a brane, on which edges of open strings stand… (More)

We find the explicit coordinate transformation which links two exact cosmological solutions of the brane world which have been recently discovered. This means that both solutions are exactly the same with each other. One of two solutions is described by the motion of a domain wall in the well-known 5-dimensional Schwarzshild-AdS spacetime. Hence, we can… (More)

We carefully investigate the gravitational perturbation of the Randall-Sundrum (RS) single braneworld solution [hep-th/9906064], based on a covariant curvature tensor formalism recently developed by us. Using this curvature formalism, it is known that the ‘electric’ part of the 5-dimensional Weyl tensor, denoted by Eμν , gives the leading order correction… (More)

We present spherically symmetric static solutions (a particle-like solution and a black hole solution) in the Einstein-Yang-Mills system with a cosmological constant. Although their gravitational structures are locally similar to those of the Bartnik-McKinnon particles or the colored black holes, the asymptotic behavior becomes quite different because of… (More)

- David Langlois, Kei-ichi Maeda, David Wands
- Physical review letters
- 2002

We consider the collision of self-gravitating n-branes in a (n+2)-dimensional spacetime. We show that there is a geometrical constraint which can be expressed as a simple sum rule for angles characterizing Lorentz boosts between branes and the intervening spacetime regions. This constraint can then be reinterpreted as either energy or momentum conservation… (More)

We discuss the phase transitions between three states of a plasma fluid (plasma ball, uniform plasma tube, and non-uniform plasma tube), which are dual to the corresponding finite energy black objects (black hole, uniform black string, and non-uniform black string) localized in an asymptotically locally AdS space. Adopting the equation of state for the… (More)

We analyze the energy extraction by the Penrose process in higher dimensions. Our result shows the efficiency of the process from higher dimensional black holes and black rings can be rather high compared with than that in four dimensional Kerr black hole. In particular, if one rotation parameter vanishes, the maximum efficiency becomes infinitely large… (More)