We study non-Gaussianity induced by a pseudo Nambu-Goldstone boson with a cosine-type scalar potential. We focus on how the non-Gaussianity is affected when the pseudo Nambu-Goldstone boson rollsâ€¦ (More)

We consider the possibility of using one of the D-flat directions in the minimal supersymmetric standard model (MSSM) as the inflaton. We show that the flat direction consisting of (first generation)â€¦ (More)

We have recently shown that, if the inflaton has a nonzero vacu um expectation value, it generically couples to any matter fields that appear in the su p rpotential at the tree level, and to anyâ€¦ (More)

We point out that supergravity effects enable the inflaton to decay into all matter fields, including the visible and the supersymmetry breaking sectors, once the inflaton acquires a non-vanishingâ€¦ (More)

We argue that a non-thermal leptogenesis occurs spontaneously, without direct couplings of the inflaton with right-handed neutrinos, in a wide class of high-scale inflation models such as the chaoticâ€¦ (More)

We investigate the cosmological moduli problem by studying a modulus decay in detail and find that the branching ratio of the gravitino production is generically of O(0.01-1), which causes anotherâ€¦ (More)

Most of the inflation models end up with non-vanishing vacuum expectation values of the inflaton fields Ï† in the true vacuum, which induce, in general, nonvanishing auxiliary field GÏ† for theâ€¦ (More)

We study the decay of the inflaton in no-scale supergravity and show that decay due to the gravitational interactions through supergravity effects is highly suppressed relative to the case in minimalâ€¦ (More)

We develop a formalism to study non-Gaussianity in both curvature and isocurvature perturbations. It is shown that non-Gaussianity in the isocurvature perturbation between dark matter and photonsâ€¦ (More)

We show that the gravitino-overproduction problem is prevalent among inflation models in supergravity. An inflaton field Ï† generically acquires (effective) nonvanishing auxiliary field G Î¦ , if theâ€¦ (More)