8 papers
Constant-Roll Inflation: Analytical Formulae for Power Spectrum and Implications for Induced Gravitational Waves
Hayato Motohashi, Shi Pi, Yuichiro Tada +1
Constant-roll inflation provides a simple and analytically tractable framework for describing transient departures from slow roll, including non-attractor phases that can enhance t…
Domain-wall Quintessence
Nobufusa Kobayashi, Yuichiro Tada, Fuminobu Takahashi +1
We investigate a dark energy model driven by a planar domain-wall-like structure with a thickness comparable to, or larger than, the current Hubble radius, focusing on its intrinsi…
Nonlinear Lattice Framework for Inflation: Bridging stochastic inflation and the formalism
Pankaj Saha, Yuichiro Tada, Yuko Urakawa
Understanding when inflationary perturbations become genuinely nonlinear near the horizon crossing requires methods that go beyond both linear perturbation theory and the gradient…
STOchastic LAttice Simulation of hybrid inflation
Tomoaki Murata, Yuichiro Tada
We investigate the spatial profile of the curvature perturbation generated in multi-waterfall hybrid inflation models, which are known to produce various topological defects. Using…
Stochastic-tail of the curvature perturbation in hybrid inflation
Tomoaki Murata, Yuichiro Tada
The exponential-tail behaviours of the probability density function (PDF) of the primordial curvature perturbation are confirmed in the mild-waterfall variants of hybrid inflation…
Dip and non-linearity in the curvature perturbation from inflation with a transient non-slow-roll stage
Tomohiro Fujita, Ryodai Kawaguchi, Misao Sasaki +1
We consider models of inflation that contain a transient non-slow-roll stage and investigate the conditions under which a dip appears in the power spectrum of the curvature perturb…