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Non-Gaussianity in Cosmic Microwave Background Temperature Fluctuations from Cosmic (Super-)Strings
Keitaro Takahashi, Atsushi Naruko, Yuuiti Sendouda +3
We compute analytically the small-scale temperature fluctuations of the cosmic microwave background from cosmic (super-)strings and study the dependence on the string intercommutin…
Large non-Gaussianity from multi-brid inflation
Atsushi Naruko, Misao Sasaki
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…
Multi-brid inflation and non-Gaussianity
Misao Sasaki
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 …
Curvature perturbation spectrum from false vacuum inflation
Jinn-Ouk Gong, Misao Sasaki
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 curvat…
Nonlinear curvature perturbations in an exactly soluble model of multi-component slow-roll inflation
Misao Sasaki
Using the nonlinear formalism, we consider a simple exactly soluble model of multi-component slow-roll inflation in which the nonlinear curvature perturbation can be evaluated…
Primordial trispectrum from inflation
Christian T. Byrnes, Misao Sasaki, David Wands
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 leadi…
Constraints on the primordial curvature perturbation from primordial black holes
Ignacio Zaballa, Anne M. Green, Karim A. Malik +1
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…
Large-scale magnetic fields in the inflationary universe
Kazuharu Bamba, Misao Sasaki
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…
Non-Gaussianity and constraints for the variance of perturbations in the curvaton model
Jussi Valiviita, Misao Sasaki, David Wands
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 emp…
Gravitational scalar field coupled directly to the Maxwell field and its effect to solar-system experiments
Yasunori Fujii, Misao Sasaki
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 the…
Non-Gaussianity of the primordial perturbation in the curvaton model
Misao Sasaki, Jussi Valiviita, David Wands
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 calcu…
Wronskian Formulation of the Spectrum of Curvature Perturbations
Shuichiro Yokoyama, Takahiro Tanaka, Misao Sasaki +1
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 fi…
Forming sub-horizon black holes at the end of inflation
David. H Lyth, Karim A. Malik, Misao Sasaki +1
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 calculati…
Conservation of nonlinear curvature perturbations on super-Hubble scales
Misao Sasaki
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 expans…
Post-inflationary behavior of adiabatic perturbations and tensor-to-scalar ratio
Andrei Linde, Viatcheslav Mukhanov, Misao Sasaki
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 univers…
A New delta N Formalism for Multi-Component Inflation
Hyun-Chul Lee, Misao Sasaki, Ewan D. Stewart +2
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…
Constraining Cosmological Parameters by the Cosmic Inversion Method
Noriyuki Kogo, Misao Sasaki, Jun'ichi Yokoyama
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…
A general proof of the conservation of the curvature perturbation
David H. Lyth, Karim A. Malik, Misao Sasaki
Without invoking a perturbative expansion, we define the cosmological curvature perturbation, and consider its behaviour assuming that the universe is smooth over a sufficiently la…
Reconstructing the Primordial Spectrum with CMB Temperature and Polarization
Noriyuki Kogo, Misao Sasaki, Jun'ichi Yokoyama
We develop a new method to reconstruct the power spectrum of primordial curvature perturbations, , by using both the temperature and polarization spectra of the cosmic microw…
A new calculation of the mass fraction of primordial black holes
Anne M. Green, Andrew R. Liddle, Karim A. Malik +1
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…
Reconstructing the Primordial Spectrum from WMAP Data by the Cosmic Inversion Method
Noriyuki Kogo, Makoto Matsumiya, Misao Sasaki +1
We reconstruct the primordial spectrum of the curvature perturbation, , from the observational data of the Wilkinson Microwave Anisotropy Probe (WMAP) by the cosmic inversion…
Relativistic stars with poloidal and toroidal magnetic fields and meridional flow
Kunihito Ioka, Misao Sasaki
We investigate stationary axisymmetric configurations of magnetized stars in the framework of general relativistic ideal magnetohydrodynamics. Our relativistic stellar model incorp…
Cosmic Inversion II --An iterative method for reproducing the primordial spectrum from the CMB data--
Makoto Matsumiya, Misao Sasaki, Jun'ichi Yokoyama
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 from the CMB…
Cosmic Inversion: Reconstructing primordial spectrum from CMB anisotropy
Makoto Matsumiya, Misao Sasaki, Jun'ichi Yokoyama
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 pro…