Boosted perturbations at the end of inflation (2009)
Zaballa, Ignacio, Sasaki, Misao
We study the effect on the primordial cosmological perturbations of a sharp transition from inflationary to a radiation and matter dominated epoch respectively. We assume that the perturbations are...
Hamiltonian formulation of f(Riemann) theories of gravity (2009)
Deruelle, Nathalie, Sasaki, Misao, Sendouda, Yuuiti, Yamauchi, Daisuke
We present a canonical formulation of gravity theories whose Lagrangian is an arbitrary function of the Riemann tensor. Our approach allows a unified treatment of various subcases and an easy...
Tensor ghosts in the inflationary cosmology (2009)
Theories with curvature squared terms in the action are known to contain ghost modes in general. However, if we regard curvature squared terms as quantum corrections to the original theory, the...
Kihara, Hironobu, Nitta, Muneto, Sasaki, Misao, Yoo, Chul-Moon, Zaballa, Ignacio
We study cosmology of the Einstein-Yang-Mills theory in ten dimensions with a quartic term in the Yang-Mills field strength. We obtain analytically a class of cosmological solutions in which the...
On the relation between positive averaged acceleration and physical observables in LTB spaces (2009)
Romano, Antonio Enea, Sasaki, Misao
As an alternative to dark energy that explains the observed acceleration of the universe, it has been suggested that we may be at the center of an inhomogeneous isotropic universe described by a...
Ando, Masaki, Kawamura, Seiji, Sato, Shuichi, Nakamura, Takashi, Tsubono, Kimio, Araya, Akito, ...
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. DECIGO is expected...
Anabalon, Andres, Deruelle, Nathalie, Morisawa, Yoshiyuki, Oliva, Julio, Sasaki, Misao, Tempo, David, ...
As is well-known, Kerr-Schild metrics linearize the Einstein tensor. We shall see here that they also simplify the Gauss-Bonnet tensor, which turns out to be only quadratic in the arbitrary...
Takahashi, Keitaro, Naruko, Atsushi, Sendouda, Yuuiti, Yamauchi, Daisuke, Yoo, Chul-Moon, Sasaki, Misao
We compute analytically the small-scale temperature fluctuations of cosmic microwave background from cosmic (super-)strings and study the dependence on the string intercommuting probability $P$. We...
Effects of particle production during inflation (2008)
Romano, Antonio Enea, Sasaki, Misao
The impact of particle production during inflation on the primordial curvature perturbation spectrum is investigated both analytically and numerically. We obtain an oscillatory behavior on small...
Spin Polarization Effects in Micro Black Hole Evaporation (2008)
Flachi, Antonino, Sasaki, Misao, Tanaka, Takahiro
We consider the evaporation of rotating micro black holes produced in highly energetic particle collisions, taking into account the polarization due to the coupling between the spin of the emitted...
Ando, Masaki, Kawamura, Seiji, Nakamura, Takashi, Tsubono, Kimio, Tanaka, Takahiro, Funaki, Ikkoh, ...
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected...
The Japanese space gravitational wave antenna; DECIGO (2008)
Kawamura, Seiji, Ando, Masaki, Nakamura, Takashi, Tsubono, Kimio, Tanaka, Takahiro, Funaki, Ikkoh, ...
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational...
Large non-Gaussianity from multi-brid inflation (2008)
Naruko, Atsushi, Sasaki, Misao
A model of multi-component hybrid inflation, dubbed multi-brid inflation, in which various observable quantities including the non-Gaussianity parameter f_{NL} can be analytically calculated was...
Multi-brid inflation and non-Gaussianity (2008)
We consider a class of multi-component hybrid inflation models whose evolution may be analytically solved under the slow-roll approximation. We call it multi-brid inflation (or $n$-brid inflation...
Curvature perturbation spectrum from false vacuum inflation (2008)
In the inflationary cosmology it occurs frequently that the inflaton field is trapped in a local, transient minimum with non-zero vacuum energy. The difficulty regarding the curvature perturbation...
"Detuned" f(R) gravity and dark energy (2008)
Deruelle, Nathalie, Sasaki, Misao, Sendouda, Yuuiti
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 field equations are...
Dynamical solution of supergravity (2008)
Binetruy, Pierre, Sasaki, Misao, Uzawa, Kunihito
We present a class of dynamical solutions for an intersecting D4-D8 brane system in ten-dimensional type IIA supergravity. The dynamical solutions reduces to a static warped AdS_6 x S^4 geometry in a...
Summary of session B4: early universe, pre-big bang, etc (2008)
In session B4—early universe, pre-big bang, etc—there were ten talks. Among them were three invited talks by Vilenkin, Ashtekar and Kodama, which highlighted the session. Here I summarize the...
Dynamical D4-D8 branes in supergravity (2007)
Binetruy, Pierre, Sasaki, Misao, Uzawa, Kunihito
We present a class of dynamical solutions for an intersecting D4-D8 brane system in ten-dimensional type IIA supergravity. The dynamical solutions reduces to a static warped AdS_6 x S^4 geometry in a...
Stability of Q-balls and Catastrophe (2007)
Sakai, Nobuyuki, Sasaki, Misao
We propose a practical method for analyzing stability of Q-balls for the whole parameter space, which includes the intermediate region between the thin-wall limit and thick-wall limit as well as...
Junction Conditions in f(R) Theories of Gravity (2007)
Deruelle, Nathalie, Sasaki, Misao, Sendouda, Yuuiti
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 class of theories by...
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...
Tanaka, Yoshiharu, Sasaki, Misao
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 approach. We adopt the...
Diagrammatic approach to non-Gaussianity from inflation (2007)
Byrnes, Christian T., Koyama, Kazuya, Sasaki, Misao, Wands, David
We present Feynman type diagrams for calculating the n-point function of the primordial curvature perturbation in terms of scalar field perturbations during inflation. The diagrams can be used to...
A Brane World in an Arbitrary Number of Dimensions without Z_2 Symmetry (2007)
Yamauchi, Daisuke, Sasaki, Misao
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 the matter on the...
Using the nonlinear $\delta N$ formalism, we consider a simple exactly soluble model of multi-component slow-roll inflation in which the nonlinear curvature perturbation can be evaluated analytically.
Gradient expansion approach to nonlinear superhorizon perturbations (2006)
Tanaka, Yoshiharu, Sasaki, Misao
Using the gradient expansion approach, we formulate a nonlinear cosmological perturbation theory on super-horizon scales valid to $O(\epsilon^2)$, where $\epsilon$ is the expansion parameter...
Constraints on the primordial curvature perturbation from primordial black holes (2006)
Zaballa, Ignacio, Green, Anne M., Malik, Karim A., Sasaki, Misao
We calculate the constraints on the primordial curvature perturbation at the end of inflation from the present day abundance of Primordial Black Holes (PBHs), as a function of the reheat temperature...
Large-scale magnetic fields in the inflationary universe (2006)
Bamba, Kazuharu, Sasaki, Misao
The generation of large-scale magnetic fields is studied in inflationary cosmology. We consider the violation of the conformal invariance of the Maxwell field by dilatonic as well as non-minimal...
Classical and quantum radiation from a moving charge in an expanding universe (2006)
Nomura, Hidenori, Sasaki, Misao, Yamamoto, Kazuhiro
We investigate photon emission from a moving particle in an expanding universe. This process is analogous to the radiation from an accelerated charge in the classical electromagnetic theory. Using...
Primordial trispectrum from inflation (2006)
Byrnes, Christian T., Sasaki, Misao, Wands, David
We use the delta N-formalism to describe the leading order contributions to the primordial power spectrum, bispectrum and trispectrum in multiple-field models of inflation at leading order in a...
Non-Gaussianity and constraints for the variance of perturbations in the curvaton model (2006)
Valiviita, Jussi, Sasaki, Misao, Wands, David
Recently, the primordial non-Gaussianity in the curvaton model has been predicted assuming sudden decay of the curvaton. We extend the calculation to non-instantaneous decay by employing delta N...
Fujii, Yasunori, Sasaki, Misao
The effect of the massless gravitational scalar field assumed to couple directly to the Maxwell field to the solar-system experiments is estimated. We start with discussing the theoretical...
Non-Gaussianity of the primordial perturbation in the curvaton model (2006)
Sasaki, Misao, Valiviita, Jussi, Wands, David
We use the delta N -formalism to investigate the non-Gaussianity of the primordial curvature perturbation in the curvaton scenario for the origin of structure. We numerically calculate the full...
Volume stabilization in a warped flux compactification model (2006)
Minamitsuji, Masato, Naylor, Wade, Sasaki, Misao
We investigate the stability of the extra dimensions in a warped, codimension two braneworld that is based upon an Einstein-Maxwell-dilaton theory with a non-vanishing scalar field potential. The...
Wronskian Formulation of the Spectrum of Curvature Perturbations (2006)
Yokoyama, Shuichiro, Tanaka, Takahiro, Sasaki, Misao, Stewart, Ewan D.
We present a new formulation for the evaluation of the primordial spectrum of curvature perturbations generated during inflation, using the fact that the Wronskian of the scalar field perturbation...
Critical escape velocity of black holes from branes (2006)
Flachi, Antonino, Pujolas, Oriol, Sasaki, Misao, Tanaka, Takahiro
In recent work we have shown that a black hole stacked on a brane escapes once it acquires a recoil velocity. This result was obtained in the {\it probe-brane} approximation, {\it i.e.}, when the...
Dynamics of domain walls intersecting black holes (2006)
Flachi, Antonino, Pujolas, Oriol, Sasaki, Misao, Tanaka, Takahiro
Previous studies concerning the interaction of branes and black holes suggested that a small black hole intersecting a brane may escape via a mechanism of reconnection. Here we consider this problem...
Forming sub-horizon black holes at the end of inflation (2005)
Lyth, David. H, Malik, Karim A., Sasaki, Misao, Zaballa, Ignacio
Previous authors have calculated the mass function of primordial black holes only on scales which are well outside the horizon at the end of inflation. Here we extend the calculation to sub-horizon...
Can thick braneworlds be self-consistent? (2005)
Minamitsuji, Masato, Naylor, Wade, Sasaki, Misao
We discuss the backreaction of a massless, minimally coupled, quantized scalar field on a thick, two-dimensional de Sitter (dS) brane as an extension of our previous work. We show that a finite brane...
Graviton emission from a higher-dimensional black hole (2005)
Cornell, A. S., Naylor, Wade, Sasaki, Misao
We discuss the graviton absorption probability (greybody factor) and the cross-section of a higher-dimensional Schwarzschild black hole (BH). We are motivated by the suggestion that a great many BHs...
Conservation of nonlinear curvature perturbations on super-Hubble scales (2005)
We consider general, non-linear curvature perturbations on scales greater than the Hubble horizon scale by invoking an expansion in spatial gradients, the so-called gradient expansion. After...
Post-inflationary behavior of adiabatic perturbations and tensor-to-scalar ratio (2005)
Linde, Andrei, Mukhanov, Viatcheslav, Sasaki, Misao
We explain why it is so difficult and perhaps even impossible to increase the cosmological tensor-to-scalar perturbation ratio during the post-inflationary evolution of the universe. Nevertheless,...
Quantum fluctuations on a thick de Sitter brane (2005)
Minamitsuji, Masato, Naylor, Wade, Sasaki, Misao
We investigate quantum fluctuations on a de Sitter (dS) brane, which has its own thickness, in order to examine whether or not the finite thickness of the brane can act as a natural cut-off for the...
Vacuum destabilization from Kaluza-Klein modes in an inflating brane (2005)
We discuss the effects from the Kaluza-Klein modes in the brane world scenario when an interaction between bulk and brane fields is included. We focus on the bulk inflaton model, where a bulk field...
A New delta N Formalism for Multi-Component Inflation (2005)
Lee, Hyun-Chul, Sasaki, Misao, Stewart, Ewan D., Tanaka, Takahiro, Yokoyama, Shuichiro
The delta N formula that relates the final curvature perturbation on comoving slices to the inflaton perturbation on flat slices after horizon crossing is a powerful and intuitive tool to compute the...
A general proof of the conservation of the curvature perturbation. (2005)
Lyth, David H., Malik, Karim A., Sasaki, Misao
Without invoking a perturbative expansion, we define the cosmological curvature perturbation, and consider its behaviour assuming that the universe is smooth over a sufficiently large comoving scale....
Constraining Cosmological Parameters by the Cosmic Inversion Method (2005)
Kogo, Noriyuki, Sasaki, Misao, Yokoyama, Jun'ichi
We investigate the question of how tightly we can constrain the cosmological parameters by using the ``cosmic inversion'' method in which we directly reconstruct the power spectrum of primordial...
Gauss-Bonnet dark energy (2005)
Nojiri, Shin'ichi, Odintsov, Sergei D., Sasaki, Misao
We propose the Gauss-Bonnet dark energy model inspired by string/M-theory where standard gravity with scalar contains additional scalar-dependent coupling with Gauss-Bonnet invariant. It is...
Kaluza-Klein gravitons are negative energy dust in brane cosmology (2005)
Minamitsuji, Masato, Sasaki, Misao, Langlois, David
We discuss the effect of Kaluza-Klein (KK) modes of bulk metric perturbations on the second Randall-Sundrum (RS II) type brane cosmology, taking the possible backreaction in the bulk and on the brane...
Self-force Regularization in the Schwarzschild Spacetime (2004)
Hikida, Wataru, Nakano, Hiroyuki, Sasaki, Misao
We discuss the gravitational self-force on a particle in a black hole space-time. For a point particle, the full (bare) self-force diverges. The metric perturbation induced by a particle can be...
Quantum Fluctuations for de Sitter Branes in Bulk AdS(5) (2004)
The vacuum expectation value of the square of the field fluctuations of a scalar field on a background consisting of {\it two} de Sitter branes embedded in an anti-de Sitter bulk are considered. We...
A general proof of the conservation of the curvature perturbation (2004)
Lyth, David H., Malik, Karim A., Sasaki, Misao
Without invoking a perturbative expansion, we define the cosmological curvature perturbation, and consider its behaviour assuming that the universe is smooth over a sufficiently large comoving scale....
Hikida, Wataru, Jhingan, Sanjay, Nakano, Hiroyuki, Sago, Norichika, Sasaki, Misao, Tanaka, Takahiro
In a previous paper, based on the black hole perturbation approach, we formulated a new analytical method for regularizing the self-force acting on a particle of small mass $\mu$ orbiting a...
Tsunesada, Yoshiki, Kanda, Nobuyuki, Nakano, Hiroyuki, Tatsumi, Daisuke, Ando, Masaki, Sasaki, Misao, ...
Gravitational radiation from a slightly distorted black hole with ringdown waveform is well understood in general relativity. It provides a probe for direct observation of black holes and...
Zeta Functions in Brane World Cosmology (2004)
Flachi, Antonino, Knapman, Alan, Naylor, Wade, Sasaki, Misao
We present a calculation of the zeta function and of the functional determinant for a Laplace-type differential operator, corresponding to a scalar field in a higher dimensional de Sitter brane...
Reconstructing the Primordial Spectrum with CMB Temperature and Polarization (2004)
Kogo, Noriyuki, Sasaki, Misao, Yokoyama, Jun'ichi
We develop a new method to reconstruct the power spectrum of primordial curvature perturbations, $P(k)$, by using both the temperature and polarization spectra of the cosmic microwave background...
A new calculation of the mass fraction of primordial black holes. (2004)
Green, Anne M., Liddle, Andrew R., Malik, Karim A., Sasaki, Misao
We revisit the calculation of the abundance of primordial black holes (PBHs) formed from primordial density perturbations, using a formation criterion derived by Shibata and Sasaki which refers to a...
Holography in Einstein Gauss-Bonnet Gravity (2004)
Ogushi, Sachiko, Sasaki, Misao
We investigate a holographic relation between Einstein Gauss-Bonnet gravity in $n$ dimensions and its dual field theory in ($n-1$) dimensions. We briefly review the AdS/CFT correspondence for the...
Linearized gravity on the de Sitter brane in the Einstein Gauss-Bonnet theory (2004)
Minamitsuji, Masato, Sasaki, Misao
We investigate the linearized gravity on a single de Sitter brane in the anti-de Sitter (AdS) bulk in the Einstein Gauss-Bonnet (EGB) theory. We find that the Einstein gravity is recovered for a high...
An Improved Search Method for Gravitational Ringing of Black Holes (2004)
Nakano, Hiroyuki, Takahashi, Hirotaka, Tagoshi, Hideyuki, Sasaki, Misao
A black hole has characteristic quasi-normal modes that will be excited when it is formed or when the geometry is perturbed. The state of a black hole when the quasi-normal modes are excited is...
A new calculation of the mass fraction of primordial black holes (2004)
Green, Anne M., Liddle, Andrew R., Malik, Karim A., Sasaki, Misao
We revisit the calculation of the abundance of primordial black holes (PBHs) formed from primordial density perturbations, using a formation criterion derived by Shibata and Sasaki which refers to a...
Local conservation law and dark radiation in cosmological braneworld (2003)
Minamitsuji, Masato, Sasaki, Misao
In the context of the Randall-Sundrum (RS) single-brane scenario, we discuss the bulk geometry and dynamics of a cosmological brane in terms of the local energy conservation law which exists for the...
Analytic Black Hole Perturbation Approach to Gravitational Radiation (2003)
Misao Sasaki, Hideyuki Tagoshi
We review the analytic methods used to perform the post-Newtonian expansion of gravitational waves induced by a particle orbiting a massive, compact body, based on black hole perturbation theory....
Reconstructing the Primordial Spectrum from WMAP Data by the Cosmic Inversion Method (2003)
Kogo, Noriyuki, Matsumiya, Makoto, Sasaki, Misao, Yokoyama, Jun'ichi
We reconstruct the primordial spectrum of the curvature perturbation, $P(k)$, from the observational data of the Wilkinson Microwave Anisotropy Probe (WMAP) by the cosmic inversion method developed...
Hikida, Wataru, Jhingan, Sanjay, Nakano, Hiroyuki, Sago, Norichika, Sasaki, Misao, Tanaka, Takahiro
We formulate a new analytical method for regularizing the self-force acting on a particle of small mass $\mu$ orbiting a black hole of mass $M$, where $\mu\ll M$. At first order in $\mu$, the...
Nakano, Hiroyuki, Sago, Norichika, Sasaki, Misao
We discuss the gravitational self-force on a particle in a black hole space-time. For a point particle, the full (bare) self-force diverges. It is known that the metric perturbation induced by a...
Reheating After Quintessential Inflation and Gravitational Waves (2003)
Tashiro, Hiroyuki, Chiba, Takeshi, Sasaki, Misao
We investigate the dependence of the gravitational wave spectrum from quintessential inflation on the reheating process. We consider two extreme reheating processes. One is the gravitational...
Analytic black hole perturbation approach to gravitational radiation (2003)
Sasaki, Misao, Tagoshi, Hideyuki
We review analytic methods to perform the post-Newtonian expansion of gravitational waves induced by a particle orbiting a massive compact body, based on the black hole perturbation theory. There...
An Effective Search Method for Gravitational Ringing of Black Holes (2003)
Nakano, Hiroyuki, Takahashi, Hirotaka, Tagoshi, Hideyuki, Sasaki, Misao
We develop a search method for gravitational ringing of black holes. The gravitational ringing is due to complex frequency modes called the quasi-normal modes that are excited when a black hole...
Newton's law on an Einstein "Gauss-Bonnet" brane (2003)
Deruelle, Nathalie, Sasaki, Misao
It is known that Newton's law of gravity holds asymptotically on a flat "brane" embedded in an anti-de Sitter "bulk" ; this was shown not only when gravity in the bulk is described by Einstein's...
Relativistic stars with poloidal and toroidal magnetic fields and meridional flow (2003)
We investigate stationary axisymmetric configurations of magnetized stars in the framework of general relativistic ideal magnetohydrodynamics. Our relativistic stellar model incorporates a toroidal...
Geometry and cosmological perturbations in the bulk inflaton model (2003)
Minamitsuji, Masato, Himemoto, Yoshiaki, Sasaki, Misao
We consider a braneworld inflation model driven by the dynamics of a scalar field living in the 5-dimensional bulk, the so-called ``bulk inflaton model'', and investigate the geometry in the bulk and...
Fermion Casimir energy for a de Sitter brane in AdS(5) (2003)
Moss, Ian G., Santiago-Germán, Wenceslao, Naylor, Wade, Sasaki, Misao
Based on some recent work of the authors, we focus on the relationship between the Casimir energy of a Majorana spinor field for a Euclidean Einstein universe $S^4\times R$ and for a Euclidean de...
Grad-Shafranov equation in noncircular stationary axisymmetric spacetimes (2003)
A formulation is developed for general relativistic ideal magnetohydrodynamics in stationary axisymmetric spacetimes. We reduce basic equations to a single second-order partial differential equation,...
Bulk quantum effects for de Sitter branes in AdS(5) (2003)
Moss, Ian G., Naylor, Wade, Santiago-Germán, Wenceslao, Sasaki, Misao
We investigate some issues regarding quantum corrections for de Sitter branes in a bulk AdS(5) spacetime. The one-loop effective action for a Majorana spinor field is evaluated and compared with the...
Braneworld inflation driven by dynamics of a bulk scalar field (2003)
Himemoto, Yoshiaki, Sasaki, Misao
We review a viable alternative scenario of the inflationary universe in the context of the Randall-Sundrum (RS) braneworld. In this scenario, the dynamics of a 5-dimensional scalar field, which we...
Massive scalar states localized on a de Sitter brane (2003)
Langlois, David, Sasaki, Misao
We consider a brane scenario with a massive scalar field in the five-dimensional bulk. We study the scalar states that are localized on the brane, which is assumed to be de Sitter. These localized...
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...
Matsumiya, Makoto, Sasaki, Misao, Yokoyama, Jun'ichi
Pursuing the original idea proposed in our previous paper (Paper I), we improve the method to determine the shape of the initial curvature perturbation spectrum $P(k)$ from the CMB data. The...
Sago, Norichika, Nakano, Hiroyuki, Sasaki, Misao
The metric perturbation induced by a particle in the Schwarzschild background is usually calculated in the Regge-Wheeler (RW) gauge, whereas the gravitational self-force is known to be given by the...
Casimir energy for de Sitter branes in bulk AdS(5) (2002)
The vacuum energy for a massless conformally coupled scalar field in a brane world set up, corresponding to de Sitter branes in a bulk anti-de Sitter spacetime, is calculated. We use the Euclidean...
Calculating the gravitational self-force in Schwarzschild spacetime (2002)
Barack, Leor, Mino, Yasushi, Nakano, Hiroyuki, Ori, Amos, Sasaki, Misao
We present a practical method for calculating the local gravitational self-force (often called “radiation-reaction force”) for a pointlike particle orbiting a Schwarzschild black hole. This is an...
Quantum Radion on de Sitter branes (2002)
The quantum fluctuation of the relative location of two (n-1)-dimensional de Sitter branes (i.e., of n spacetime dimensions) embedded in the (n+1)-dimensional anti-de Sitter bulk, which we shall call...
Calculating the gravitational self force in Schwarzschild spacetime (2002)
Barack,Leor, Mino,Yasushi, Nakano,Hiroyuki, Ori,Amos, Sasaki,Misao
We present a practical method for calculating the local gravitational self-force (often called "radiation-reaction force") for a pointlike particle orbiting a Schwarzschild black hole. This is an...
Calculating the gravitational self force in Schwarzschild spacetime (2002)
Barack, Leor, Mino, Yasushi, Nakano, Hiroyuki, Ori, Amos, Sasaki, Misao
We present a practical method for calculating the local gravitational self-force (often called "radiation-reaction force") for a pointlike particle orbiting a Schwarzschild black hole. This is an...
Bulk scalar field in the braneworld can mimic the 4D inflaton dynamics (2001)
Himemoto, Yoshiaki, Tanaka, Takahiro, Sasaki, Misao
Based on the recently proposed scenario of inflation driven by a bulk scalar field in the braneworld of the Randall-Sundrum (RS) type, we investigate the dynamics of a bulk scalar field on the...
Cosmic Inversion: Reconstructing primordial spectrum from CMB anisotropy (2001)
Matsumiya, Makoto, Sasaki, Misao, Yokoyama, Jun'ichi
We investigate the possibility of reconstructing the initial spectrum of density fluctuations from the cosmic microwave background (CMB) anisotropy. As a first step toward this program, we consider a...
Mino, Yasushi, Nakano, Hiroyuki, Sasaki, Misao
Covariant structure of the self-force of a particle in a general curved background has been made clear in the cases of scalar [Quinn], electromagnetic [DeWittBrehme], and gravitational charges...
Calculating the gravitational self force in Schwarzschild spacetime (2001)
Barack, Leor, Mino, Yasushi, Nakano, Hiroyuki, Ori, Amos, Sasaki, Misao
We present a practical method for calculating the local gravitational self-force (often called ``radiation-reaction force'') for a pointlike particle orbiting a Schwarzschild black hole. This is an...
Correlated perturbations from inflation and the cosmic microwave background (2001)
Amendola, Luca, Gordon, Christopher, Wands, David, Sasaki, Misao
We compare the latest cosmic microwave background data with theoretical predictions including correlated adiabatic and CDM isocurvature perturbations with a simple power-law dependence. We find that...
Quantum fluctuations in brane-world inflation without inflaton on the brane (2001)
Sago, Norichika, Himemoto, Yoshiaki, Sasaki, Misao
A Randall-Sundrum type brane-cosmological model in which slow-roll inflation on the brane is driven solely by a bulk scalar field was recently proposed by Himemoto and Sasaki. We analyze their model...
Self-Force on a Scalar Charge in Circular Orbit around a Schwarzschild Black Hole (2001)
Nakano, Hiroyuki, Mino, Yasushi, Sasaki, Misao
In an accompanying paper, we have formulated two types of regulariz_ation methods to calculate the scalar self-force on a particle of charge $q$ moving around a black hole of mass $M$, one of which...
Enhancement of superhorizon scale inflationary curvature perturbations (2001)
Leach, Samuel M, Sasaki, Misao, Wands, David, Liddle, Andrew R
We show that there exists a simple mechanism which can enhance the amplitude of curvature perturbations on superhorizon scales during inflation, relative to their amplitude at horizon crossing. The...
Large-scale cosmological perturbations on the brane (2000)
Langlois, David, Maartens, Roy, Sasaki, Misao, Wands, David
In brane-world cosmologies of Randall-Sundrum type, we show that evolution of large-scale curvature perturbations may be determined on the brane, without solving the bulk perturbation equations. The...
Radion on the de Sitter brane (2000)
The radion on the de Sitter brane is investigated at the linear perturbation level, using the covariant curvature tensor formalism developed by Shiromizu, Maeda and Sasaki. It is found that if there...
Brane-world inflation without inflaton on the brane (2000)
Himemoto, Yoshiaki, Sasaki, Misao
Inspired by the Randall-Sundrum brane-world scenario, we investigate the possibility of brane-world inflation driven not by an inflaton field on the brane, but by a bulk, dilaton-like gravitational...
Gravitational reaction force on a particle in the Schwarzschild background (2000)
Nakano, Hiroyuki, Sasaki, Misao
We formulate a new method to calculate the gravitational reaction force on a particle of mass $\mu$ orbiting a massive black hole of mass $M$. In this formalism, the tail part of the retarded Green...
We examine the polarization signal of the cosmic microwave background radiation associated with distant clusters. The polarization is induced by the Thomson scattering of microwave photons with...
Gravity, Stability and Energy Conservation on the Randall-Sundrum Brane-World (1999)
Sasaki, Misao, Shiromizu, Tetsuya, Maeda, Kei-ichi
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...
False Vacuum Decay With Gravity in Non-Thin-Wall Limit (1999)
We consider a wave-function approach to the false vacuum decay with gravity and present a new method to calculate the tunneling amplitude under the WKB approximation. The result agrees with the one...
Brane-world creation and black holes (1999)
An inflating brane-world can be created from ``nothing'' together with its Anti-de Sitter (AdS) bulk. The resulting space-time has compact spatial sections bounded by the brane. During inflation, the...
The Einstein Equations on the 3-Brane World (1999)
Shiromizu, Tetsuya, Maeda, Kei-ichi, Sasaki, Misao
We carefully investigate the gravitational equations of the brane world, in which all the matter forces except gravity are confined on the 3-brane in a 5-dimensional spacetime with $Z_2$ symmetry. We...
Shibata, Masaru, Sasaki, Misao
We study formation of black holes in the Friedmann universe. We present a formulation of the Einstein equations under the constant mean curvature time-slicing condition. Our formalism not only gives...
Linde, Andrei, Sasaki, Misao, Tanaka, Takahiro
The possibility to have an infinite open inflationary universe inside a bubble of a finite size is one of the most interesting realizations extensively discussed in the literature. The original idea...
Spectrum of Cosmological Perturbations in the One-Bubble Open Universe (1998)
Garriga, Jaume, Montes, Xavier, Sasaki, Misao, Tanaka, Takahiro
The spectrum of cosmological perturbations in the context of the one-bubble open inflation model is discussed, taking into account fluctuations of the metric. We find that, quite generically,thin...
No supercritical supercurvature mode conjecture in one-bubble open inflation (1998)
Tanaka, Takahiro, Sasaki, Misao
In the path integral approach to false vacuum decay with the effect of gravity, there is an unsolved problem, called the negative mode problem. We show that the appearance of a supercritical...
Innermost stable circular orbits around relativistic rotating stars (1998)
Shibata, Masaru, Sasaki, Misao
We investigate the innermost stable circular orbit (ISCO) of a test particle moving on the equatorial plane around rotating relativistic stars such as neutron stars. First, we derive approximate...
Super-Horizon Scale Dynamics of Multi-Scalar Inflation (1998)
Sasaki, Misao, Tanaka, Takahiro
We consider the dynamics of a multi-component scalar field on super-horizon scales in the context of inflationary cosmology. We present a method to solve the perturbation equations on super- horizon...
Gravitational Radiation Reaction (1997)
Mino, Yasushi, Sasaki, Misao, Tanaka, Takahiro
We consider the radiation reaction to the motion of a point-like particle of mass $m$ and specific spin $S$ traveling on a curved background. Assuming $S=O(Gm)$ and $Gm\ll L$ where $L$ is the length...
Black Hole Perturbation (1997)
Mino, Yasushi, Sasaki, Misao, Shibata, Masaru, Tagoshi, Hideyuki, Tanaka, Takahiro
We present analytic calculations of gravitational waves from a particle orbiting a black hole. We first review the Teukolsky formalism for dealing with the gravitational perturbation of a black hole....
Gravitational Waves from Coalescing Black Hole MACHO Binaries (1997)
Nakamura, Takashi, Sasaki, Misao, Tanaka, Takahiro, Thorne, Kip S.
If MACHOs are black holes of mass about 0.5 solar mass, they must have been formed in the early universe when the temperature was about 1 GeV. We estimate that in this case in our galaxy's halo out...
Canonical Quantization of Cosmological Perturbations in the One Bubble Open Universe (1997)
Garriga, Jaume, Montes, Xavier, Sasaki, Misao, Tanaka, Takahiro
Faddeev and Jackiw's method for constrained systems is used to derive a gauge invariant formulation of cosmological perturbations in the one bubble inflationary universe. For scalar perturbations in...
Gravitational Radiation Reaction to a Particle Motion II: Spinning Particle (1997)
Mino, Yasushi, Sasaki, Misao, Tanaka, Takahiro
We discuss the leading order correction to the equation of motion of a particle with spin on an arbitrary spacetime. A particle traveling in a curved spacetime is known to trace a geodesic of the...
Wall fluctuation modes and tensor CMB anisotropy in open inflation models (1997)
Sasaki, Misao, Tanaka, Takahiro, Yakushige, Yoshihiro
We calculate the spectrum of large angle cosmic microwave background (CMB) anisotropies due to quantum fluctuations of the gravitational wave modes in one-bubble open inflation models. We find the...
The Spectrum of Gravitational Wave Perturbations in the One-Bubble Open Inflationary Universe (1997)
Tanaka, Takahiro, Sasaki, Misao
We give the initial spectrum of quantized gravitational waves in the context of the one-bubble open inflationary universe scenario. In determining the quantum state after the bubble nucleation we...
Quantized gravitational waves in the Milne universe (1996)
Tanaka, Takahiro, Sasaki, Misao
The quantization of gravitational waves in the Milne universe is discussed. The relation between positive frequency functions of the gravitational waves in the Milne universe and those in the...
Gravitational Radiation Reaction to a Particle Motion (1996)
Mino, Yasushi, Sasaki, Misao, Tanaka, Takahiro
In this paper, we discuss the leading order correction to the equation of motion of the particle, which presumably describes the effect of gravitational radiation reaction. We derive the equation of...
Can the Simplest Two-Field Model of Open Inflation Survive? (1996)
Sasaki, Misao, Tanaka, Takahiro
We investigate the quantum fluctuations of an inflaton field in a two-field model of one-bubble open inflation. One of the inflatons is assumed to be responsible for the first false vacuum stage of...
Quantum fluctuations and CMB anisotropies in one-bubble open inflation models (1996)
Yamammoto, Kazuhiro, Sasaki, Misao, Tanaka, Takahiro
We first develop a method to calculate a complete set of mode functions which describe the quantum fluctuations generated in one-bubble open inflation models. We consider two classes of models. One...
Tagoshi, Hideyuki, Shibata, Masaru, Tanaka, Takahiro, Sasaki, Misao
Extending a method developed by Sasaki in the Schwarzschild case and by Shibata, Sasaki, Tagoshi, and Tanaka in the Kerr case, we calculate the post-Newtonian expansion of the gravitational wave...
Gravitational waves from a spinning particle in circular orbits around a rotating black hole (1996)
Tanaka, Takahiro, Mino, Yasushi, Sasaki, Misao, Shibata, Masaru
Using the Teukolsky and Sasaki-Nakamura formalisms for the perterbations around a Kerr black hole, we calculate the energy flux of gravitational waves induced by a {\it spinning} particle of mass...
Self Excitation of the Tunneling Scalar Field in False Vacuum Decay (1995)
Hamazaki, Takashi, Sasaki, Misao, Tanaka, Takahiro, Yamamoto, Kazuhiro
A method to determine the quantum state of a scalar field after $O(4)$-symmetric bubble nucleation has been developed recently. The method has an advantage that it concisely gives us a clear picture...
Sasaki, Misao, Stewart, Ewan D.
The standard calculation of the spectrum of density perturbations produced during inflation assumes that there is only one real dynamical degree of freedom during inflation. However, there is no...
Large Angle CMB Anisotropy in an Open Universe in the One-Bubble Inflationary Scenario (1995)
Yamamoto, Kazuhiro, Sasaki, Misao, Tanaka, Takahiro
We consider an alternative scenario of inflation which can account for a spatially open universe. It is similar to the old inflation in which the bubble nucleation occurs in the sea of false vacuum,...
Euclidian Vacuum Mode Functions for a Scalar Field on Open De Sitter Spacetime (1994)
Sasaki, Misao, Tanaka, Takahiro, Yamamoto, Kazuhiro
Motivated by recent studies of the one-bubble inflationary universe scenario that predicts a low density, negative curvature universe, we investigate the Euclidean vacuum mode functions of a scalar...
A particle of mass $\mu$ moves on a circular orbit of a nonrotating black hole of mass $M$. Under the restrictions $\mu/M \ll 1$ and $v \ll 1$, where $v$ is the orbital velocity, we consider the...
Particle Spectrum Created Through Bubble Nucleation (1994)
Yamamoto, Kazuhiro, Tanaka, Takahiro, Sasaki, Misao
Using the multi-dimensional wave function formalism, we investigate the quantum state of a scalar field inside a true vacuum bubble nucleated through false vacuum decay in flat spacetime. We...
Shibata, Masaru, Sasaki, Misao, Tagoshi, Hideyuki, Tanaka, Takahiro
Using the Teukolsky and Sasaki-Nakamura equations for the gravitational perturbation of the Kerr spacetime, we calculate the post-Newtonian expansion of the energy and angular momentum luminosities...
Skewness of CMB Anisotropies in an Inflationary Isocurvature Baryon Model (1994)
Yamamoto, Kazuhiro, Sasaki, Misao
We investigate the cosmic variance of the skewness of the cosmic microwave background (CMB) anisotropies in an inflationary model which leads to the baryon isocurvature scenario for the cosmic...
Quantum State During and after $O(4)$-Symmetric Bubble Nucleation with Gravitaional Effects (1994)
TANAKA, Takahiro, SASAKI, Misao
We extend our previous analysis of the quantum state during and after $O(4)$-symmetric bubble nucleation to the case including gravitational effects. We find that there exists a simple relationship...
Probability Distribution of Primordial Angular Momentum and Formation of Massive Black Holes (1994)
Susa, Hajime, Sasaki, Misao, Tanaka, Takahiro
We consider the joint probability distribution function for the mass contrast and angular momentum of over-density regions on the proto- galactic scale and investigate the formation of massive black...
Tagoshi, Hideyuki, Sasaki, Misao
Based upon the formalism recently developed by one of us (MS), we analytically perform the post-Newtonian expansion of gravitational waves from a test particle in circular orbit of radius $r_0$...
Post-Newtonian Expansion of the Ingoing-Wave Regge-Wheeler Function (1994)
We present a method of post-Newtonian expansion to solve the homogeneous Regge-Wheeler equation which describes gravitational waves on the Schwarzschild spacetime. The advantage of our method is that...
General Solutions for Tunneling of Scalar Fields with Quartic Potentials in de Sitter Space (1994)
Sasaki, Misao, Stewart, Ewan D., Tanaka, Takahiro
The tunneling rates for scalar fields with quartic potentials in de Sitter space in the limit of no gravitational back reaction are calculated numerically and the results are fitted by analytic...