We present in a manifestly gauge-invariant form the theory of classical linear gravitational
perturbations in part I, and a quantum theory of cosmological perturbations in part II. Part I …

Gravitational waves (GWs) have a great potential to probe cosmology. We review early
universe sources that can lead to cosmological backgrounds of GWs. We begin by …

The Early Universe has become the standard reference on forefront topics in cosmology,
particularly to the early history of the Universe. Subjects covered include primordial …

We identify a new cosmological problem for models which solve the strong CP puzzle with
an invisible axion, unrelated to the domain wall problem. Because the axion is very weakly …

The creation and evolution of energy-density perturbations are analyzed for the" new
inflationary universe" scenario proposed by Linde, and Albrecht and Steinhardt. According …

Reheating after inflation occurs due to particle production by the oscillating inflaton field. In
this paper we briefly describe the perturbative approach to reheating, and then concentrate …

The theory of reheating of the Universe after inflation is developed. We have found that
typically at the first stage of reheating the classical inflation field φ rapidly decays into φ …

The linear perturbation theory of spatially homogeneous and isotropic universes is reviewed
and reformulated extensively. In the first half of the article, a gauge-invariant formulation of …

We review potential low-frequency gravitational-wave sources, which are expected to be
detected by Taiji, a Chinese space-based gravitational-wave detector, estimate the detection …

A new mechanism for baryogenesis is proposed. It is argued that, after inflation, the scalar
quarks and leptons of a supersymmetric GUT may have large expectation values. The …