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Tetsuya Shiromizu

Publications and source records attributed to Tetsuya Shiromizu.

At least 109 records · Page 6Linked to original sources
arXiv2003

Can we live on a D-brane? -- Effective theory on a self-gravitating D-brane --

We consider a D-brane coupled with gravity in type IIB supergravity on S^5 and derive the effective theory on the D-brane in two different ways, that is, holographic and geometrical projection methods. We find that the effective equations on the brane obtained by these methods coincide. The theory on the D-brane described by the Born-Infeld action is not like Einstein-Maxwell theory in the lower order of the gradient expansion, i.e., the Maxwell field does not appear in the theory. Thus the careful analysis and statement for cosmology on self-gravitating D-brane should be demanded in realistic models.

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arXiv2003

D-braneworld cosmology

We discuss D-braneworld cosmology, that is, the brane is described by the Born-Infeld action. Compared with the usual Randall-Sundrum braneworld cosmology where the brane action is the Nambu-Goto one, we can see some drastic changes at the very early universe: (i)universe may experience the rapid accelerating phase (ii)the closed universe may avoid the initial singularity. We also briefly address the dynamics of the cosmology in the open string metric, which might be favorer than the induced metric from the view point of the D-brane.

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arXiv2003

Effective theory for close limit of two branes

We discuss the effective theory for the close limit of two branes in a covariant way. To do so we solve the five dimensional Einstein equation along the direction of the extra dimension. Using the Taylor expansion we solve the bulk spacetimes and derive the effective theory describing the close limit. We also discuss the radion dynamics and braneworld black holes for the close limit in our formulation.

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arXiv2003

Low energy effective theory for two branes system

We derive the low energy effective theory for two branes system solving the bulk geometry formally in the covariant curvature formalism developed by Shiromizu, Maeda and Sasaki. As expected, the effective theory looks like a Einstein-scalar system. Using this theory we can discuss the cosmology and non-linear gravity at low energy scales.

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arXiv2002

Cosmological constant, dilaton field and Freund-Rubin compactification

We discuss the Freund-Rubin compactification with cosmological constant and the dilaton field, and examine the stability of the spacetimes at the low energy. The Minkowski or de Sitter spacetime can be obtained if the dilation field is turned off while we observe that the dilaton field does not permit such spacetimes but only the anti-de Sitter spacetime. The stability of the spacetime depends on the dimensions of the spacetime and the compactified space and the coupling constant of the dilaton field $a$. In the $a=1$ case, which corresponds to superstring theories, the anti-de Sitter vacuum is stable at least in the linear level.

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arXiv2002

Uniqueness and non-uniqueness of static black holes in higher dimensions

We prove a uniqueness theorem for asymptotically flat static charged dilaton black hole solutions in higher dimensional space-times. We also construct infinitely many non-asymptotically flat regular static black holes on the same space-time manifold with the same spherical topology. An application to the uniqueness of a certain class of flat $p$-branes is also given.

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arXiv2001

Gravitational energy, dS/CFT correspondence and cosmic no-hair

The gravitational energy is examined in asymptotically de Sitter space-times. The positivity will be shown for certain cases. The de Sitter/CFT(dS/CFT) correspondence recently proposed and cosmic no-hair conjecture are testified in the aspect of the gravitational energy. From the holographic renormalization group point of view, the two conjectures are deeply connected with each other.

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arXiv2001

Brane-World and Holography

We consider the brane-world in the holographic point of view. Bearing the realistic models in mind, the bulk massless scalar field is introduced. First of all, we find the constraint on the coupling of the scalar fields with the matter(not holographic CFT) on the brane. We show that the traceless part of the energy-momentum tensor of holographic CFT is a part of the bulk Weyl tensor. The trace part which comes from the trace-anomaly is corresponding to the $ρ^2$-term appeared in the generalized FRW equation in the brane-world.

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arXiv2001

Semiclassical instability of the brane-world: Randall-Sundrum bubbles

We discuss the semiclassical instability of the Randall-Sundrum brane-world model against a creation of a kind of Kaluza-Klein bubble. An example describing such a bubble space-time is constructed from the five-dimensional AdS-Schwarzschild metric. The induced geometry of the brane looks like the Einstein-Rosen bridge, which connects the positive and the negative tension branes. The bubble rapidly expands and there also form a trapped region around it.

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arXiv2001

Stability of $AdS_p x S^n x S^{q-n}$ Compactifications

We examine the stability of ${\rm AdS}_p \times {\rm S}^n \times {\rm S}^{q-n}$. The initial data constructed by De Wolfe et al \cite{Gary} has been carefully analyised and we have confirmed that there is no lower bound for the total mass for $q< 9$. The effective action on ${\rm AdS}_p$ has been derived for dilatonic compactification of the system to describe the non-linear fluctuation of the background space-time. The stability is discussed applying the positive energy theorem to the effective theory on AdS, which again shows the stability for $q \geq 9$.

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arXiv2001

Anti-de Sitter no-hair, AdS/CFT and the brane-world

We study the asymptotic behavior of the bulk spacetimes with the negative cosmological constant in the context of the brane-world scenario. We show that, in Euclidean bulk, or in Lorentzian static bulk, some sequences of hypersurfaces with the positive Ricci scalar evolve to the warped geometries like the anti-de Sitter spacetime. Based on the AdS/CFT correspondence, we discuss that the positivity of the Ricci scalar is related to the stability of CFT on the brane. In addition, the brane-world is described from the holographic point of view. The asymptotic local structure of the conformal infinity is also investigated.

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arXiv2000

Charged Brane-World Black Holes

We study charged brane-world black holes in the model of Randall and Sundrum in which our universe is viewed as a domain wall in asymptotically anti-de Sitter space. Such black holes can carry two types of ``charge'', one arising from the bulk Weyl tensor and one from a gauge field trapped on the wall. We use a combination of analytical and numerical techniques to study how these black holes behave in the bulk. It has been shown that a Reissner-Nordstrom geometry is induced on the wall when only Weyl charge is present. However, we show that such solutions exhibit pathological features in the bulk. For more general charged black holes, our results suggest that the extent of the horizon in the fifth dimension is usually less than for an uncharged black hole that has the same mass or the same horizon radius on the wall.

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arXiv2000

Black holes in the brane world:Time symmetric initial data

We numerically construct time-symmetric initial data sets of a black hole in the Randall-Sundrum brane world model, assuming that the black hole is spherical on the brane. We find that the apparent horizon is cigar-shaped in the 5D spacetime.

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arXiv2000

Global structure of exact cosmological solutions in the brane world

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 easily understand the region covered by the coordinate used by another solution.

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arXiv2000

Fate of Kaluza-Klein Bubble

We numerically study classical time evolutions of Kaluza-Klein bubble space-time which has negative energy after a decay of vacuum. As the zero energy Witten's bubble space-time, where the bubble expands infinitely, the subsequent evolutions of Brill and Horowitz's momentarily static initial data show that the bubble will expand in terms of the area. At first glance, this result may support Corley and Jacobson's conjecture that the bubble will expand forever as well as the Witten's bubble. The irregular signatures, however, can be seen in the behavior of the lapse function in the maximal slicing gauge and the divergence of the Kretchman invariant. Since there is no appearance of the apparent horizon, we suspect an appearance of a naked singularity as the final fate of this space-time.

hep-th↗
arXiv2000

Gravity, Stability and Energy Conservation on the Randall-Sundrum Brane-World

We carefully investigate the gravitational perturbation of the Randall-Sundrum (RS) single brane-world 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 $E_{μν}$, gives the leading order correction to the conventional Einstein equations on the brane. We consider the general solution of the perturbation equations for the 5-dimensional Weyl tensor caused by the matter fluctuations on the brane. By analyzing its asymptotic behaviour in the direction of the 5th dimension, we find the curvature invariant diverges as we approach the Cauchy horizon. However, in the limit of asymptotic future in the vicinity of the Cauchy horizon, the curvature invariant falls off fast enough to render the divergence harmless to the brane-world. We also obtain the asymptotic behavior of $E_{μν}$ on the brane at spatial infinity, assuming the matter perturbation is localized. We find it falls off sufficiently fast and will not affect the conserved quantities at spatial infinity. This indicates strongly that the usual conservation law, such as the ADM energy conservation, holds on the brane as far as asymptotically flat spacetimes are concerned.

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