1.2k citations · 13.2k across the 177 of their papers we have counts for
21 papers · 1 filter
Note on the bispectrum and one-loop corrections in single-field inflation with primordial black hole formation
Jason Kristiano, Jun'ichi Yokoyama
Primordial black holes can be formed from the collapse of large-amplitude perturbation on small scales in the early Universe. Such an enhanced spectrum can be realized by introduci…
Constraining Primordial Black Hole Formation from Single-Field Inflation
Jason Kristiano, Jun'ichi Yokoyama
The most widely studied formation mechanism of a primordial black hole is collapse of large-amplitude perturbation on small scales generated in single-field inflation. In this Lett…
Perturbative region on non-Gaussian parameter space in single-field inflation
Jason Kristiano, Jun'ichi Yokoyama
We calculate one-loop correction to the two-point functions of curvature perturbation in single-field inflation generated by cubic self-interaction. Incorporating the observed red-…
Vacuum decay in the Lorentzian path integral
Takumi Hayashi, Kohei Kamada, Naritaka Oshita +1
We apply the Lorentzian path integral to the decay of a false vacuum and estimate the false-vacuum decay rate. To make the Lorentzian path integral convergent, the deformation of a…
Why Must Primordial Non-Gaussianity Be Very Small?
Jason Kristiano, Jun'ichi Yokoyama
One-loop correction to the power spectrum in generic single-field inflation is calculated by using standard perturbation theory. Because of the enhancement inversely proportional t…
On catalyzed vacuum decay around a radiating black hole and the crisis of the electroweak vacuum
Takumi Hayashi, Kohei Kamada, Naritaka Oshita +1
False vacuum decay is a key feature in quantum field theories and exhibits a distinct signature in the early Universe cosmology. It has recently been suggested that the false vacuu…
Particle production induced by vacuum decay in real time dynamics
Soichiro Hashiba, Yusuke Yamada, Jun'ichi Yokoyama
We discuss particle production associated with vacuum decay, which changes the mass of a scalar field coupled to a background field which induces the decay. By utilizing the Stokes…
Horndeski model in nonlinearly realized supergravity
Yusuke Yamada, Jun'ichi Yokoyama
We construct the Horndeski Lagrangian within non-linearly realized supergravity. We will show that the bosonic part of the Horndeski Lagrangian can be realized. Gravitino naturally…
Loop corrections to primordial fluctuations from inflationary phase transitions
Yi-Peng Wu, Jun'ichi Yokoyama
We investigate loop corrections to the primordial fluctuations in the single-field inflationary paradigm from spectator fields that experience a smooth transition of their vacuum e…
Note on Reheating in G-inflation
Hossein Bazrafshan Moghaddam, Robert Brandenberger, Jun'ichi Yokoyama
We study particle production at the end of inflation in kinetically driven G-inflation model and show that, in spite of the fact that there are no inflaton oscillations and hence n…
Fermionic Schwinger effect and induced current in de Sitter space
Takahiro Hayashinaka, Tomohiro Fujita, Jun'ichi Yokoyama
We explore Schwinger effect of spin 1/2 charged particles with static electric field in 1+3 dimensional de Sitter spacetime. We analytically calculate the vacuum expectation value…
Entropic interpretation of the Hawking-Moss bounce
Naritaka Oshita, Jun'ichi Yokoyama
We revisit the derivation of the Hawking-Moss transition rate. Using the static coordinates, we show that the Euclidean action is entirely determined by the contribution of the ent…
Galilean Creation of the Inflationary Universe
Tsutomu Kobayashi, Masahide Yamaguchi, Jun'ichi Yokoyama
It has been pointed out that the null energy condition can be violated stably in some non-canonical scalar-field theories. This allows us to consider the Galilean Genesis scenario…
Topological inflation from the Starobinsky model in supergravity
Kohei Kamada, Jun'ichi Yokoyama
We consider the ghost-free higher order corrections to the Starobinsky model in the old minimal supergravity. In general, higher order corrections cannot be forbidden by symmetries…
Gravitational modulated reheating and non-Gaussianity in Supergravity R^2 inflation
Yuki Watanabe, Jun'ichi Yokoyama
Reheating after R^2 inflation proceeds through gravitational particle production of conformally noninvariant fields. We argue that the nonvanishing expectation value of flat direct…
Consequences of a stochastic approach to the conformal invariance of inflationary correlators
Hayato Motohashi, Teruaki Suyama, Jun'ichi Yokoyama
We provide a general formalism to calculate the infrared correlators of multiple interacting scalar fields in the de Sitter space by means of the stochastic approach. These scalar…
Generalized G-inflation: Inflation with the most general second-order field equations
Tsutomu Kobayashi, Masahide Yamaguchi, Jun'ichi Yokoyama
We study generalized Galileons as a framework to develop the most general single-field inflation models ever, Generalized G-inflation, containing yet further generalization of G-in…
Primordial non-Gaussianity from G-inflation
Tsutomu Kobayashi, Masahide Yamaguchi, Jun'ichi Yokoyama
We present a comprehensive study of primordial fluctuations generated from G-inflation, in which the inflaton Lagrangian is of the form with $X=-(\partialϕ)^…
G-inflation: inflation driven by the Galileon field
Tsutomu Kobayashi, Masahide Yamaguchi, Jun'ichi Yokoyama
We propose a new class of inflation model, G-inflation, which has a Galileon-like nonlinear derivative interaction of the form in the Lagrangian with the r…
Geometrically Consistent Approach to Stochastic DBI Inflation
Larissa Lorenz, Jerome Martin, Jun'ichi Yokoyama
Stochastic effects during inflation can be addressed by averaging the quantum inflaton field over Hubble-patch sized domains. The averaged field then obeys a Langevin-type equation…
A cosmological constant from degenerate vacua
Jun'ichi Yokoyama
Under the hypothesis that the cosmological constant vanishes in the true ground state with lowest possible energy density, we argue that the observed small but finite vacuum-like e…