activity
20242026
collaborators

7 papers

astro-ph.CO2026

Time-reversed stochastic inflation in the quantum well

Chiara Animali, Baptiste Blachier, Nanoka Okada +3

Time-reversed stochastic inflation solves the stochastic evolution of the inflationary universe backward in time, by counting the number of e-folds from the end of quantum diffusio…

astro-ph.CO2026

Primordial black holes in excursion set theory: Formation probabilities, mass functions, and window functions

Hayami Iizuka, Daiki Saito, Koki Tokeshi

We study the mass function of primordial black holes (PBHs) within the excursion-set theory, in which the response of the stochastic density contrast to the variation of the coarse…

astro-ph.CO2026

Multifield stochastic inflation: Relevance of number of fields in statistical moments

Tomo Takahashi, Koki Tokeshi

In multifield inflation driven by scalar fields, symmetry renders the number of fields irrelevant at classical level. This ceases to be the case once stochastic effects…

astro-ph.CO2026

Primordial black holes and smooth coarse-graining in excursion set theory

Daiki Saito, Koki Tokeshi

The excursion-set formalism enables us to infer the mass distribution of collapsed objects, such as primordial black holes (PBHs), by the language of stochastic processes. Within t…

hep-th2025

Scalar field stochastic dynamics in de Sitter spacetime from exact solutions of quantum deficient oscillators

Yuta Nasuda, Koki Tokeshi, Yuki Watanabe

The stochastic dynamics of a scalar field in de Sitter spacetime can be regarded as a non-perturbative diffusion process, to which exact distribution and correlation functions are…

astro-ph.CO2025

More fields are different: Stochastic view of multi-field inflationary scenario

Tomo Takahashi, Koki Tokeshi

High-energy physics often motivates multi-field inflationary scenarios where stochastic effects play a crucial role. Peculiar to multi-field models, the noise-induced centrifugal f…