219 citations · 2.3k across the 55 of their papers we have counts for
6 papers · 1 filter
Anisotropic -form dark energy
Juan P. Beltrán Almeida, Alejandro Guarnizo, Ryotaro Kase +2
We study the dynamics of dark energy in the presence of a 2-form field coupled to a canonical scalar field . We consider the coupling proportional to $e^{-μϕ/M_{\rm pl}} H_{αβγ}…
Instabilities in Horndeski Yang-Mills inflation
Jose Beltran Jimenez, Lavinia Heisenberg, Ryotaro Kase +2
A non-abelian gauge field with a non-minimal Horndeski coupling to gravity gives rise to a de Sitter solution followed by a graceful exit to a radiation-dominated epoch. In…
Beyond generalized Proca theories
Lavinia Heisenberg, Ryotaro Kase, Shinji Tsujikawa
We consider higher-order derivative interactions beyond second-order generalized Proca theories that propagate only the three desired polarizations of a massive vector field beside…
Effective field theory approach to modified gravity including Horndeski theory and Hořava-Lifshitz gravity
Ryotaro Kase, Shinji Tsujikawa
We review the effective field theory of modified gravity in which the Lagrangian involves three dimensional geometric quantities appearing in the 3+1 decomposition of space-time. O…
Cosmology in generalized Horndeski theories with second-order equations of motion
Ryotaro Kase, Shinji Tsujikawa
We study the cosmology of an extended version of Horndeski theories with second-order equations of motion on the flat Friedmann-Lemaître-Robertson-Walker (FLRW) background. In addi…
Effective field theory of modified gravity on the spherically symmetric background: leading order dynamics and the odd-type perturbations
Ryotaro Kase, László Árpád Gergely, Shinji Tsujikawa
We consider perturbations of a static and spherically symmetric background endowed with a metric tensor and a scalar field in the framework of the effective field theory of modifie…