Zobrazeno 1 - 10
of 26
pro vyhledávání: '"Shimada, Keigo"'
Publikováno v:
Prog Theor Exp Phys (2023)
We show the well-posed variational principle in constraint systems. In a naive procedure of the variational principle with constraints, the proper number of boundary conditions does not match with that of physical degrees of freedom dynamical variabl
Externí odkaz:
http://arxiv.org/abs/2303.03805
We propose a new non-trivial way to combine mimetic dark matter with the mimetic formulation of unimodular gravity. This yields a Weyl-invariant higher-derivative scalar-vector-tensor theory. We demonstrate that on-shell its behavior mimics GR with a
Externí odkaz:
http://arxiv.org/abs/2212.14867
Publikováno v:
JHEP 07 (2023) 154
We show that invertible transformations of dynamical variables can change the number of dynamical degrees of freedom. Moreover, even in cases when the number of dynamical degrees of freedom remains unchanged, the resulting dynamics can be essentially
Externí odkaz:
http://arxiv.org/abs/2208.05951
Publikováno v:
JCAP 11 (2022) 019
We analyse the dynamical properties of disformally transformed theories of gravity. We show that disformal transformation typically introduces novel degrees of freedom, equivalent to the mimetic dark matter, which possesses a Weyl-invariant formulati
Externí odkaz:
http://arxiv.org/abs/2207.12611
Publikováno v:
JCAP 04 (2021) 028
We show that promoting the trace part of the Einstein equations to a trivial identity results in the Newton constant being an integration constant. Thus, in this formulation the Newton constant is a global dynamical degree of freedom which is also a
Externí odkaz:
http://arxiv.org/abs/2011.07055
We investigate cosmological perturbations of scalar-tensor theories in Palatini formalism. First we introduce an action where the Ricci scalar is conformally coupled to a function of a scalar field and its kinetic term and there is also a k-essence t
Externí odkaz:
http://arxiv.org/abs/2010.07867
Autor:
Aoki, Katsuki, Shimada, Keigo
Publikováno v:
Phys. Rev. D 100, 044037 (2019)
We reveal the existence of a certain hidden symmetry in general ghost-free scalar-tensor theories which can only be seen when generalizing the geometry of the spacetime from Riemannian. For this purpose, we study scalar-tensor theories in the metric-
Externí odkaz:
http://arxiv.org/abs/1904.10175
Publikováno v:
Phys. Rev. D 99, 104020 (2019)
We classify the metric-affine theories of gravitation, in which the metric and the connections are treated as independent variables, by use of several constraints on the connections. Assuming the Einstein-Hilbert action, we find that the equations fo
Externí odkaz:
http://arxiv.org/abs/1812.03420
Autor:
Aoki, Katsuki, Shimada, Keigo
Publikováno v:
Phys. Rev. D 98, 044038 (2018)
We study scalar-tensor theories respecting the projective invariance in the metric-affine formalism. The metric-affine formalism is a formulation of gravitational theories such that the metric and the connection are independent variables in the first
Externí odkaz:
http://arxiv.org/abs/1806.02589
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