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Graviton non-gaussianity in -vacuum
Sugumi Kanno, Misao Sasaki
We compute the leading order non-Gaussianity, i.e., the bispectrum, of the tensor perturbation in the general -vacuum on de Sitter space in general relativity. In addition to th…
Solving information loss paradox via Euclidean path integral
Pisin Chen, Misao Sasaki, Dong-han Yeom +1
The information loss paradox associated with black hole Hawking evaporation is an unresolved problem in modern theoretical physics. In this paper, we revisit the entanglement entro…
Cosmology of strongly interacting fermions in the early universe
Guillem Domènech, Misao Sasaki
In view of growing interest in long range scalar forces in the early universe to generate primordial black holes, we study in detail the general relativistic formulation of a Fermi…
Hawking radiation as instantons
Pisin Chen, Misao Sasaki, Dong-han Yeom
There have been various interpretations of Hawking radiation proposed based on the perturbative approach, and all have confirmed Hawking's original finding. One major conceptual ch…
Quantum entanglement in de Sitter space with a wall, and the decoherence of bubble universes
Andreas Albrecht, Sugumi Kanno, Misao Sasaki
We study the effect of a bubble wall on the entanglement entropy of a free massive scalar field between two causally disconnected open charts in de Sitter space. We assume there is…
Vacuum State of the Dirac Field in de Sitter Space and Entanglement Entropy
Sugumi Kanno, Misao Sasaki, Takahiro Tanaka
We compute the entanglement entropy of a free massive Dirac field between two causally disconnected open charts in de Sitter space. We first derive the Bunch-Davies vacuum mode fun…
Acausality in Nonlocal Gravity Theory
Ying-li Zhang, Kazuya Koyama, Misao Sasaki +1
We investigate the nonlocal gravity theory by deriving nonlocal equations of motion using the traditional variation principle in a homogeneous background. We focus on a class of mo…
Stationary bubbles and their tunneling channels toward trivial geometry
Pisin Chen, Guillem Domènech, Misao Sasaki +1
In the path integral approach, one has to sum over all histories that start from the same initial condition in order to obtain the final condition as a superposition of histories.…
Naked Black Hole Firewalls
Pisin Chen, Yen Chin Ong, Don N. Page +2
In the firewall proposal, it is assumed that the firewall lies near the event horizon and should not be observable except by infalling observers, who are presumably terminated at t…
Homogeneous Instantons in Bigravity
Ying-li Zhang, Misao Sasaki, Dong-han Yeom
We study homogeneous gravitational instantons, conventionally called the Hawking-Moss (HM) instantons, in bigravity theory. The HM instantons describe the amplitude of quantum tunn…
Thin-shell bubbles and information loss problem in anti de Sitter background
Misao Sasaki, Dong-han Yeom
We study the motion of thin-shell bubbles and their tunneling in anti de Sitter (AdS) background. We are interested in the case when the outside of a shell is a Schwarzschild-AdS s…
Schwinger effect in de Sitter space
Markus B. Fröb, Jaume Garriga, Sugumi Kanno +4
We consider Schwinger pair production in 1+1 dimensional de Sitter space, filled with a constant electric field . This can be thought of as a model for describing false vacuum d…
Coleman-de Luccia instanton in dRGT massive gravity
Ying-li Zhang, Ryo Saito, Dong-han Yeom +1
We study the Coleman-de Luccia (CDL) instanton characterizing the tunneling from a false vacuum to the true vacuum in a semi-classical way in dRGT (deRham-Gabadadze-Tolley) massive…
Equilateral non-Gaussianity from heavy fields
Jinn-Ouk Gong, Shi Pi, Misao Sasaki
The effect of self-interactions of heavy scalar fields during inflation on the primordial non-Gaussianity is studied. We take a specific constant-turn quasi-single field inflation…
Fluid Inflation
Xingang Chen, Hassan Firouzjahi, Mohammad Hossein Namjoo +1
In this work we present an inflationary mechanism based on fluid dynamics. Starting with the action for a single barotropic perfect fluid, we outline the procedure to calculate the…
A Single Field Inflation Model with Large Local Non-Gaussianity
Xingang Chen, Hassan Firouzjahi, Mohammad Hossein Namjoo +1
A detection of large local form non-Gaussianity is considered to be able to rule out all single field inflation models. This statement is based on a single field consistency condit…
Hawking-Moss instanton in nonlinear massive gravity
Ying-li Zhang, Ryo Saito, Misao Sasaki
As a first step toward understanding a lanscape of vacua in a theory of non-linear massive gravity, we consider a landscape of a single scalar field and study tunneling between a p…
Observer dependence of bubble nucleation and Schwinger pair production
Jaume Garriga, Sugumi Kanno, Misao Sasaki +2
Pair production in a constant electric field is closely analogous to bubble nucleation in a false vacuum. The classical trajectories of the pairs are Lorentz invariant, but it appe…
Multiple Inflationary Stages with Varying Equation of State
Mohammad Hossein Namjoo, Hassan Firouzjahi, Misao Sasaki
We consider a model of inflation consisting a single fluid with a time-dependent equation of state. In this phenomenological picture, two periods of inflation are separated by an i…
Destabilizing Tachyonic Vacua at or above the BF Bound
Sugumi Kanno, Misao Sasaki, Jiro Soda
It is well known that tachyonic vacua in an asymptotically Anti-de Sitter (AdS) space-time are classically stable if the mass squared is at or above the Breitenlohner and Freedman…
Tunneling without barriers with gravity
Sugumi Kanno, Misao Sasaki, Jiro Soda
We consider the vacuum decay of the flat Minkowski space to an anti-de Sitter space. We find a one-parameter family of potentials that allow exact, analytical instanton solutions d…
Holographic Dual of de Sitter Universe with AdS Bubbles
Sugumi Kanno, Misao Sasaki, Jiro Soda
We study the proposal that a de Sitter (dS) universe with an Anti-de Sitter (AdS) bubble can be replaced by a dS universe with a boundary CFT. To explore this duality, we consider…
Open inflation in the landscape
Daisuke Yamauchi, Andrei Linde, Atsushi Naruko +2
Open inflation scenario is attracting a renewed interest in the context of string landscape. Since there are a large number of metastable de Sitter vacua in string landscape, tunne…
Screening of cosmological constant for De Sitter Universe in non-local gravity, phantom-divide crossing and finite-time future singularities
Kazuharu Bamba, Shin'ichi Nojiri, Sergei D. Odintsov +1
We investigate de Sitter solutions in non-local gravity as well as in non-local gravity with Lagrange constraint multiplier. We examine a condition to avoid a ghost and discuss a s…