165 citations · 2.5k across the 85 of their papers we have counts for
7 papers · 1 filter
Can baryon asymmetry be explained by a large initial value before inflation?
Kai Murai, Fuminobu Takahashi, Masaki Yamada +1
We show that the baryon asymmetry of the Universe cannot be explained by a large initial value before inflation because it inevitably predicts correlated baryon isocurvature pertur…
Stochastic dynamics of multi-waterfall hybrid inflation and formation of primordial black holes
Yuichiro Tada, Masaki Yamada
We show that a hybrid inflation model with multiple waterfall fields can result in the formation of primordial black hole (PBH) with an astrophysical size, by using an advanced alg…
On the primordial black hole formation in hybrid inflation
Yuichiro Tada, Masaki Yamada
We revisit the scenario of primordial black hole (PBH) formation from large curvature perturbations generated during the waterfall phase transition in hybrid inflation models. In a…
Gravitational Waves and Dark Radiation from Dark Phase Transition: Connecting NANOGrav Pulsar Timing Data and Hubble Tension
Yuichiro Nakai, Motoo Suzuki, Fuminobu Takahashi +1
Recent pulsar timing data reported by the NANOGrav collaboration may indicate the existence of a stochastic gravitational wave background around Hz. We explore a p…
Anthropic Bound on Dark Radiation and its Implications for Reheating
Fuminobu Takahashi, Masaki Yamada
We derive an anthropic bound on the extra neutrino species, , based on the observation that a positive suppresses the growth of matter fluctuations due…
Isocurvature Perturbations of Dark Energy and Dark Matter from the Swampland Conjecture
Hiroki Matsui, Fuminobu Takahashi, Masaki Yamada
We point out that the recently proposed Swampland conjecture on the potential gradient can lead to isocurvature perturbations of dark energy, if the quintessence field acquires lar…
Primordial Black Holes from Polynomial Potentials in Single Field Inflation
Mark P. Hertzberg, Masaki Yamada
Within canonical single field inflation models, we provide a method to reverse engineer and reconstruct the inflaton potential from a given power spectrum. This is not only a usefu…