96 citations · 1.2k across the 37 of their papers we have counts for
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Extended mimetic gravity: Hamiltonian analysis and gradient instabilities
Kazufumi Takahashi, Tsutomu Kobayashi
We propose a novel class of degenerate higher-order scalar-tensor theories as an extension of mimetic gravity. By performing a noninvertible conformal transformation on "seed" scal…
Stable black holes in shift-symmetric Horndeski theories
Daria A. Tretyakova, Kazufumi Takahashi
In shift-symmetric Horndeski theories, a static and spherically symmetric black hole can support linearly time-dependent scalar hair. However, it was shown that such a solution gen…
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…