Outline
PURPOSE
The academic area of this research is dedicated to direct observations of the cosmic evolution through the inflation epoch to the structure formation epoch via cosmic background radiations and the quest for the ultimate theory behind inflation on the basis of these observations. In order to achieve this goal, it is essential that we perform theoretical studies on what kind of information the observed data obtained by very accurate CMB polarization measurements and IR observations can bring us on the early evolution of the Universe and the ultimate theory behind it. The purpose of our research program is to conduct such theoretical studies together with major domestic cosmologies to construct a unified cosmological model that is consistent with all observations at the end, in collaboration with experimental researchers in this field and on the basis of that to pin down candidates for the ultimate theory behind.
HOW TO PROCEED
In this research program, it is necessary that we quickly carry out difficult tasks that require advanced skills and knowledge in many aspects. Hence, we carry out the program by joining forces of the co-investigators with their own expertise and technology and by obtaining the cooperation of variety of researchers, including the collaborators, through proposed researches.
Considering the current status of researches in this field, we focus on the two themes: “Systematic study of perturbations produced by the inflationary universe” and “Construction of the inflation model based on the unified theory including gravity”.
The first theme aims to narrow down inflation models by comparing observations with the results of systematic calculations of observed quantities for various models. In particular, in addition to the limits on the energy scale of inflation that will be obtained by the ongoing ground-based B-mode polarization measurements such as QUIET and PolarBeaR, the complementary Planck satellite mission will provide us the information on the statistics of perturbations (non-Gaussianity) that will further constrain inflation models at the phenomenological level. We will also be preparing for primordinal gravitaional wave observations by future B-mode polarization measurements by satellites like LiteBIRD and EPIC, and for observations of the gravitational field fluctuations by means of galaxies and Lyman alpha clouds.
For the second theme, we will conduct two studies in parallel to each other; a study of the cosmological model based on the 4-D unified theory in which the crosspoint to low energy physics has been established, and a study for extracting the 4-D theory from a candidate of the ultimate theory, M-theory/superstring theory. We will proceed with the former within the framework of supergravity, however will reevaluate its direction once the results of the highest energy accelerator experiment LHC become available. On the other hand, for the study of the ultimate theory, we will explore the path leading to more realistic 4-D Cosmological models by going beyond the current standard framework. At the same time, we attempt to discover new observable information that enables us to test its own characteristic features of the ultimate theory, such as parity violation in space-time perturbation statistics, through observations of CMB and gravitational wave.