864 citations · 11k across the 237 of their papers we have counts for
12 papers · 1 filter
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…
Where does curvaton reside? Differences between bulk and brane frames
François Larrouturou, Shinji Mukohyama, Ryo Namba +1
Some classes of inflationary models naturally introduce two distinct metrics/frames, and their equivalence in terms of observables has often been put in question. D-brane inflation…
Stealth magnetic field in de Sitter spacetime
Shinji Mukohyama
In the context of a U(1) gauge theory non-minimally coupled to scalar-tensor gravity, we find a cosmological attractor solution that represents a de Sitter universe with a homogene…
Graviton mass might reduce tension between early and late time cosmological data
Antonio De Felice, Shinji Mukohyama
The standard -CDM predicts a growth of structures which tends to be higher than the values of redshift space distortion (RSD) measurements, if the cosmological parameters are fi…
Jeans' Ghost
A. Emir Gumrukcuoglu, Shinji Mukohyama, Thomas P. Sotiriou
We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar's gradie…
Is the DBI scalar field as fragile as other -essence fields?
Shinji Mukohyama, Ryo Namba, Yota Watanabe
Caustic singularity formations in shift-symmetric -essence and Horndeski theories on a fixed Minkowski spacetime were recently argued. In dimensions, this singularity is the…