277 citations · 1k across the 23 of their papers we have counts for
8 papers · 1 filter
Singular instantons with finite action
Misao Sasaki, Vicharit Yingcharoenrat, Ying-li Zhang
Recently, it was shown that in the absence of gravity there exist non--symmetric instanton solutions with finite action beyond Coleman's instantons. In this paper, focusing o…
Beyond Coleman's Instantons
Misao Sasaki, Vicharit Yingcharoenrat, Ying-li Zhang
In the absence of gravity, Coleman's theorem states that the -symmetric instanton solution, which is regular at the origin and exponentially decays at infinity, gives the low…
Stable solutions of inflation driven by vector fields
Razieh Emami, Shinji Mukohyama, Ryo Namba +1
Many models of inflation driven by vector fields alone have been known to be plagued by pathological behaviors, namely ghost and/or gradient instabilities. In this work, we seek a…
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…
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…
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…
Cosmological Solutions of a Nonlocal Model with a Perfect Fluid
Emilio Elizalde, Ekaterina O. Pozdeeva, Sergey Yu. Vernov +1
A nonlocal gravity model which does not assume the existence of a new dimensional parameter in the action and includes a function , with the d'Alembertian op…
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…