Cosmological Magnetic Fields from Inflation and Backreaction (2009)
Kanno, Sugumi, Soda, Jiro, Watanabe, Masa-aki
We study the backreaction problem in a mechanism of magnetogenesis from inflation. In usual analysis, it has been assumed that the backreaction due to electromagnetic fields spoils inflation once it...
Holographic Superconductors with Higher Curvature Corrections (2009)
Gregory, Ruth, Kanno, Sugumi, Soda, Jiro
We study (3+1)-dimensional holographic superconductors in Einstein-Gauss-Bonnet gravity both numerically and analytically. It is found that higher curvature corrections make condensation harder. We...
Watanabe, Masa-aki, Kanno, Sugumi, Soda, Jiro
We study an inflationary scenario with a vector field coupled with an inflaton field. We show that the inflationary universe is endowed with anisotropic hair for a wide range of coupling functions....
Anisotropic Inflation from Vector Impurity (2008)
Kanno, Sugumi, Kimura, Masashi, Soda, Jiro, Yokoyama, Shuichiro
We study an inflationary scenario with a vector impurity. We show that the universe undergoes anisotropic inflationary expansion due to a preferred direction determined by the vector. Using the...
Modified Friedmann Equation and Inflation in Warped Codimension-two Braneworld (2007)
Chen, Fang, Cline, James M., Kanno, Sugumi
We study the Friedmann equation for the warped codimension-two braneworld background which most closely resembles the Randall-Sundrum model. Extra matter on the (Planck) 4-brane, with equation of...
Kaluza-Klein braneworld cosmology with static internal dimensions (2007)
Kanno, Sugumi, Langlois, David, Sasaki, Misao, Soda, Jiro
We investigate the Kaluza-Klein braneworld cosmology from the point of view of observers on the brane. We first generalize the Shiromizu-Maeda-Sasaki (SMS) equations to higher dimensions. As an...
Satoh, Masaki, Kanno, Sugumi, Soda, Jiro
We study a mechanism to produce the circular polarization of primordial gravitational waves. The circular polarization is generated during the super-inflation driven by the Gauss-Bonnet term in the...
Emergence of Fluctuations from a Tachyonic Big Bang (2007)
Brandenberger, Robert H., Frey, Andrew R., Kanno, Sugumi
It has recently been speculated that the end state of a collapsing universe is a tachyonic big crunch. The time reversal of this process would be the emergence of an expanding universe from a...
Towards A Nonsingular Tachyonic Big Crunch (2007)
Brandenberger, Robert H., Frey, Andrew R., Kanno, Sugumi
We discuss an effective field theory background containing the gravitational field, the dilaton and a closed string tachyon, and couple this background to a gas of fundamental strings and D strings....
Fate of Kaluza-Klein Black Holes: Evaporation or Excision? (2007)
Murata, Keiju, Soda, Jiro, Kanno, Sugumi
We study evaporation process of black strings which are typical examples of Kaluza-Klein black holes. Taking into account the backreaction of the Hawking radiation, we deduce the evolution equation...
Evaporating (2+1)-dimensional black strings (2007)
Murata, Keiju, Soda, Jiro, Kanno, Sugumi
We investigate (2+1)-dimensional black strings in the Kaluza-Klein spacetime. The system is classically stable as long as the horizon size is much larger than the size of the compact space....
Impact of Lorentz Violation on Cosmology (2006)
We discuss the impact of Lorentz violation on the cosmology. Firstly, we show that the Lorentz violation affects the dynamics of the chaotic inflationary model and gives rise to an interesting...
More on the Spectrum of Perturbations in String Gas Cosmology (2006)
Brandenberger, Robert H., Kanno, Sugumi, Soda, Jiro, Easson, Damien A., Khoury, Justin, Martineau, Patrick, ...
String gas cosmology is rewritten in the Einstein frame. In an effective theory in which a gas of closed strings is coupled to a dilaton gravity background without any potential for the dilaton, the...
Lorentz Violating Inflation (2006)
We explore the impact of Lorentz violation on the inflationary scenario. More precisely, we study the inflationary scenario in the scalar-vector-tensor theory where the vector is constrained to be...
Moduli Stabilization in String Gas Compactification (2005)
We investigate the moduli stabilization in string gas compactification. We first present a numerical evidence showing the stability of the radion and the dilaton. To understand this numerical result,...
Braneworld Cosmological Perturbation Theory at Low Energy (2005)
Homogeneous cosmology in the braneworld can be studied without solving bulk equations of motion explicitly. The reason is simply because the symmetry of the spacetime restricts possible corrections...
Black String Perturbations in RS1 Model (2005)
We present a general formalism for black string perturbations in Randall-Sundrum 1 model (RS1). First, we derive the master equation for the electric part of the Weyl tensor $E_{\mu\nu}$. Solving the...
Braneworld Flux Inflation (2005)
Kanno, Sugumi, Soda, Jiro, Wands, David
We propose a geometrical model of brane inflation where inflation is driven by the flux generated by opposing brane charges and terminated by the collision of the branes, with charge annihilation. We...
Low Energy Effective Action for Horava-Witten Cosmology (2005)
As a supersymmetric extension of the Randall-Sundrum model, we consider a 5-dimensional Horava-Witten type theory, and derive its low energy effective action. The model we consider is a two-brane...
We present a general formalism for studying an inflationary scenario in the two-brane system. We explain the gradient expansion method and obtain the 4-dimensional effective action. Based on this...
On The Higher Codimension Braneworld (2004)
We study a codimension 2 braneworld in the Einstein-Gauss-Bonnet gravity. In the linear regime, we show the conventional Einstein gravity can be recovered on the brane. While, in the nonlinear...
On the Validity of a Factorizable Metric Ansatz in String Cosmology (2004)
To support the validity of a factorizable metric ansatz used in string cosmology, we investigate a toy problem in RSI model. For this purpose, we revise the gradient expansion method to conform to...
A Unified View of RS Braneworlds (2004)
There are various different descriptions of Randall-Sundrum (RS) braneworlds. Here we present a unified view of the braneworld based on the gradient expansion approach. In the case of the...
Quasi-Thick Codimension 2 Braneworld (2004)
We study a codimension 2 braneworld in the Einstein Gauss-Bonnet gravity. We carefully examine the structure of possible singularities in the system which characterize the braneworld through matching...
Gravitational Waves from Rotating Black Strings (2003)
In the Randall-Sundrum two-brane model (RS1), a Kerr black hole on the brane can be naturally identified with a section of rotating black string. To estimate Kaluza-Klein (KK) corrections on...
A Novel Approach to Braneworld (2003)
Evaluating Kaluza-Klein (KK) corrections is indispensable to test the braneworld scenario. In this report, we propose a novel symmetry approach to an effective 4-dimensional action with KK...
Effective Teukolsky Equation on the Brane (2003)
To estimate Kaluza-Klein (KK) corrections on gravitational waves emitted by perturbed rotating black strings, we give the effective Teukolsky equation on the brane which is separable equation and...
Radionic Non-uniform Stable Black Strings (2003)
Tamaki, Takashi, Kanno, Sugumi, Soda, Jiro
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of...
Inflationary Braneworld Driven By Bulk Scalar Field (2003)
We have developed a formalism to study an inflationary scenario driven by a bulk inflaton in the two-brane system. The 4-dimensional low energy effective action is obtained using the gradient...
Braneworld Kaluza-Klein Corrections in a Nutshell (2003)
Evaluating Kaluza-Klein (KK) corrections is indispensable to test the braneworld scenario. In this paper, we propose a novel symmetry approach to a 4-dimensional effective action with KK corrections...
Radionic Non-uniform Black Strings --short version-- (2003)
Tamaki, Takashi, Kanno, Sugumi, Soda, Jiro
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of...
Rotating Black String and Effective Teukolsky Equation in Braneworld (2003)
In the Randall-Sundrum two-brane model (RS1), a Kerr black hole on the brane can be naturally identified with a section of rotating black string. To estimate Kaluza-Klein (KK) corrections on...
Radionic Non-uniform Black Strings (2003)
Tamaki, Takashi, Kanno, Sugumi, Soda, Jiro
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of the black strings. From the brane...
We derive the low energy effective action for the dilatonic braneworld. In the case of the single-brane model, we find the effective theory is described by the Einstein-scalar theory coupled to the...
Non-linear Gravity on Branes and Effective Action (2003)
We develop the general formalism to study the low energy regime of the brane world. We apply our formalism to the single brane model where the AdS/CFT correspondence will take an important role. We...
Kanno, Sugumi, Sasaki, Misao, Soda, Jiro
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. In this scenario,...
Kanno, Sugumi, Sasaki, Misao, Soda, Jiro
We propose a cosmological braneworld scenario in which two branes collide and emerge as reborn branes whose tensions have signs opposite to the original tensions of the respective branes. In this...
Holographic View of Cosmological Perturbations (2002)
The cosmological perturbation theory is revisited from the holographic point of view. In the case of the single brane model, it turns out that the AdS/CFT correspondence plays an important role. In...
Braneworld Effective Action at Low Energies (2002)
The low energy effective theory for the Randall-Sundrum two-brane system is investigated with an emphasis on the role of the non-linear radion in the brane world. It is shown that the gravity on the...
Radion and Holographic Brane Gravity (2002)
The low energy effective theory for the Randall-Sundrum two brane system is investigated with an emphasis on the role of the non-linear radion in the brane world. The equations of motion in the bulk...
Brane World Effective Action at Low Energies and AdS/CFT Correspondence (2002)
A low energy iteration scheme to study nonlinear gravity in the brane world is developed. As a result, we obtain the brane world effective action at low energies. The relation between the geometrical...