334 citations · 4k across the 75 of their papers we have counts for
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Ghost-free theory with third-order time derivatives
Hayato Motohashi, Teruaki Suyama, Masahide Yamaguchi
As the first step to extend our understanding of higher-derivative theories, within the framework of analytic mechanics of point particles, we construct a ghost-free theory involvi…
Primordial Black Holes and Slow-Roll Violation
Hayato Motohashi, Wayne Hu
For primordial black holes (PBH) to be the dark matter in single-field inflation, the slow-roll approximation must be violated by at least in order to enhance the cur…
constant-roll inflation
Hayato Motohashi, Alexei A. Starobinsky
The previously introduced class of two-parametric phenomenological inflationary models in General Relativity in which the slow-roll assumption is replaced by the more general, cons…
Generalized Slow Roll in the Unified Effective Field Theory of Inflation
Hayato Motohashi, Wayne Hu
We provide a compact and unified treatment of power spectrum observables for the effective field theory (EFT) of inflation with the complete set of operators that lead to second-or…
Constant-roll inflation: confrontation with recent observational data
Hayato Motohashi, Alexei A. Starobinsky
The previously proposed class of phenomenological inflationary models in which the assumption of inflaton slow-roll is replaced by the more general, constant-roll condition is comp…
General invertible transformation and physical degrees of freedom
Kazufumi Takahashi, Hayato Motohashi, Teruaki Suyama +1
An invertible field transformation is such that the old field variables correspond one-to-one to the new variables. As such, one may think that two systems that are related by an i…