41 citations · 62 across the 4 of their papers we have counts for
7 papers · 1 filter
String Excitation by Initial Singularity of Inflation
Kanji Nishii, Daisuke Yoshida
We discuss excitation of string oscillation modes by an initial singularity of inflation. The initial singularity of inflation is known to occur with a finite Hubble parameter, whi…
invariant Fierz-Pauli massive gravity
Toshifumi Noumi, Kaishu Saito, Jiro Soda +1
We consider an invariant massive deformation of double field theory at the level of free theory. We study Kaluza-Klein reduction on and…
Birth of de Sitter Universe from time crystal
Daisuke Yoshida, Jiro Soda
We show that a simple sub-class of Horndeski theory can describe a time crystal Universe. The time crystal Universe can be regarded as a baby Universe nucleated from a flat space,…
2-form gauge theory dual to scalar-tensor theory
Daisuke Yoshida
We generalize the electromagnetic duality between a massless, canonical scalar field and a 2-form gauge field in 4-dimensional spacetime to scalar-tensor theories. We derive the ac…
Global Spacetime Structure of Compactified Inflationary Universe
Tokiro Numasawa, Daisuke Yoshida
We investigate the global spacetime structure of torus de Sitter universe, which is exact de Sitter space with torus identification based on the flat chart. We show that past incom…
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…