219 citations · 2.3k across the 55 of their papers we have counts for
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Instability of compact stars with a nonminimal scalar-derivative coupling
Ryotaro Kase, Shinji Tsujikawa
For a theory in which a scalar field has a nonminimal derivative coupling to the Einstein tensor of the form , it is known that there exis…
Stability of relativistic stars with scalar hairs
Ryotaro Kase, Rampei Kimura, Seiga Sato +1
We study the stability of relativistic stars in scalar-tensor theories with a nonminimal coupling of the form , where depends on a scalar field and is the Ricci…
General formulation of cosmological perturbations in scalar-tensor dark energy coupled to dark matter
Ryotaro Kase, Shinji Tsujikawa
For a scalar field coupled to cold dark matter (CDM), we provide a general framework for studying the background and perturbation dynamics on the isotropic cosmological backgro…
Neutron star cooling in modified gravity theories
Akira Dohi, Ryotaro Kase, Rampei Kimura +2
We study thermal evolution of isolated neutron stars in scalar-tensor theories for the first time. Whether the rapid cooling due to the direct Urca process occurs or not is an inte…
Neutron stars with a generalized Proca hair and spontaneous vectorization
Ryotaro Kase, Masato Minamitsuji, Shinji Tsujikawa
In a class of generalized Proca theories, we study the existence of neutron star solutions with a nonvanishing temporal component of the vector field approaching 0 toward spa…