109 citations · 613 across the 27 of their papers we have counts for
4 papers · 1 filter
Higher derivative scalar-tensor theory through a non-dynamical scalar field
Xian Gao, Masahide Yamaguchi, Daisuke Yoshida
We propose a new class of higher derivative scalar-tensor theories without the Ostrogradsky's ghost instabilities. The construction of our theory is originally motivated by a scala…
Stable cosmological solutions in degenerate theory of gravity
Ryotaro Kase, Rampei Kimura, Atsushi Naruko +1
We study cosmological applications of extended vector-tensor theories, whose Lagrangians contain up to two derivatives with respect to metric and vector field. We derive background…
Maximal extensions and singularities in inflationary spacetimes
Daisuke Yoshida, Jerome Quintin
Extendibility of inflationary spacetimes with flat spatial geometry is investigated. We find that the past boundary of an inflationary spacetime becomes a so-called parallely propa…
Singularities in Spherically Symmetric Solutions with Limited Curvature Invariants
Daisuke Yoshida, Robert H. Brandenberger
We investigate static, spherically symmetric solutions in gravitational theories which have limited curvature invariants, aiming to remove the singularity in the Schwarzschild spac…