40 citations · 151 across the 5 of their papers we have counts for
7 papers · 1 filter
How does gravity save or kill Q-balls?
Takashi Tamaki, Nobuyuki Sakai
We explore stability of gravitating Q-balls with potential via catastrophe theory, as an extension of our previous work on Q-balls with…
Unified picture of Q-balls and boson stars via catastrophe theory
Takashi Tamaki, Nobuyuki Sakai
We make an analysis of Q-balls and boson stars using catastrophe theory, as an extension of the previous work on Q-balls in flat spacetime. We adopt the potential $V_3(ϕ)={m^2\over…
The universe out of a monopole in the laboratory?
Nobuyuki Sakai, Ken-ichi Nakao, Hideki Ishihara +1
To explore the possibility that an inflationary universe can be created out of a stable particle in the laboratory, we consider the classical and quantum dynamics of a magnetic mon…
Generality of Topological Inflation
Nobuyuki Sakai
Many authors claimed that a large initial inhomogeneity prevents the onset of inflation and therefore inflation takes place only if the scalar field is homogeneous or appropriately…
Evolution of Black Holes in Brans-Dicke Cosmology
Nobuyuki Sakai, John D. Barrow
We consider a modified ``Swiss cheese'' model in the Brans-Dicke theory, and discuss the evolution of black holes in the expanding universe. We define the black hole radius by the…
Topological Defect Inflation
Nobuyuki Sakai
We address some issues of topological defect inflation. (1) We clarify the causal structure of an inflating magnetic monopole. The spacetime diagram shows explicitly that this mode…