12 citations · 12 across the 1 of their papers we have counts for
5 papers
Massive fermion production in nonsingular superstring cosmology
Shinji Tsujikawa, Hiroki Yajima
We study massive spin-1/2 fermion production in nonsingular superstring cosmology, taking into account one-loop quantum corrections to a superstring effective action with dilaton a…
New constraints on multi-field inflation with nonminimal coupling
Shinji Tsujikawa, Hiroki Yajima
We study the dynamics and perturbations during inflation and reheating in a multi-field model where a second scalar field is nonminimally coupled to the scalar curvature $(\fra…
Black hole solutions in Euler-Heisenberg theory
Hiroki Yajima, Takashi Tamaki
We construct static and spherically symmetric black hole solutions in the Einstein-Euler-Heisenberg (EEH) system which is considered as an effective action of a superstring theory.…
Generality of Singularity Avoidance in Superstring Theory: Anisotropic Case
Hiroki Yajima, Kei-ichi Maeda, Hidetoshi Ohkubo
In one-loop string effective action, we study a generality of non-singular cosmological solutions found in the isotropic and homogeneous case. We discuss Bianchi I and IX type spac…
Dilatonic Black Holes with Gauss-Bonnet Term
Takashi Torii, Hiroki Yajima, Kei-ichi Maeda
We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field and the Gauss-Bonnet term. Assuming U(1) or SU(2) symm…