Naoya Omoto

Entropy production by domain wall decay in the NMSSM

We consider domain walls in the

Small field axion inflation with sub-Planckian decay constant

Z_3

Constraints on small-field axion inflation

symmetric NMSSM. The spontaneous

Supersymmetry preserving and breaking degenerate vacua, and radiative moduli stabilization

Z_3

Possible altitudinal, latitudinal, and directional dependence of the relativistic Sagnac effect in Chern-Simons modified gravity

discrete symmetry breaking produces domain walls, and the stable domain walls are problematic. Thus, we assume the

Radiative Kähler moduli stabilization RADIATIVE KÄHLER MODULI STABILIZATION KOBAYASHI et al.

Z_3

Dilution of axion dark radiation

symmetry is slightly but explicitly broken and the domain walls decay. Such a decay causes a large late-time entropy production. We study its cosmological implications on unwanted relics such as moduli, gravitino, LSP and axion.

Dilution of axion dark radiation by thermal inflation

We study an axion inflation model recently proposed within the framework of type IIB superstring theory, where we pay a particular attention to a sub-Planckian axion decay constant. Our axion potential can lead to the small field inflation with a small tensor-to-scalar ratio, and a typical reheating temperature can be as low as GeV.

Modular

We study general class of small-field axion inflations which are the mixture of polynomial and sinusoidal functions suggested by the natural and axion monodromy inflations. The axion decay constants leading to the successful axion inflations are severely constrained in order not to spoil the Big-Bang nucleosynthesis and overproduce the isocurvature perturbation originating from the QCD axion. We in turn find that the cosmologically favorable axion decay constants are typically of order the grand unification scale or the string scale which is consistent with the prediction of closed string axions.

A_4

We propose a new type of moduli stabilization scenario where the supersymmetric and supersymmetry-breaking minima are degenerate at the leading level. The inclusion of the loop-corrections originating from the matter fields resolves this degeneracy of vacua. Light axions are predicted in one of our models.