Zobrazeno 1 - 10
of 93
pro vyhledávání: '"Miritzis, John"'
Publikováno v:
Eur. Phys. J. C (2023) 83:433
We propose a new formulation of $f(R)$ gravity, dubbed scalarized $f(R)$ gravity, in which the Legendre transform is included as a dynamical term. This leads to a theory with second-order field equations that describes general relativity with a self-
Externí odkaz:
http://arxiv.org/abs/2305.04011
Publikováno v:
Eur. Phys. J. C 83, 735 (2023)
We discuss implications of the cosmological frame principle which states that cosmological effects of modified gravity must be stable as solutions of each of the corresponding sets of dynamical equations holding in the two conformally-related frames.
Externí odkaz:
http://arxiv.org/abs/2304.12733
Autor:
Cotsakis, Spiros, Miritzis, John
Publikováno v:
Mathematics 11 (2023) 633
We study the effects of trans-planckian censorship conjecture (TCC) bounds on geodesic completeness of spacetime and the associated existence for an infinite proper time. Using Gronwall's lemma, TCC bounds can be derived directly, leading to a result
Externí odkaz:
http://arxiv.org/abs/2301.00156
Publikováno v:
Eur. Phys. J. C82 (2022) 785
We study the problem of evolution of bulk 5-fluids having an embedded braneworld with a flat, de Sitter, or anti-de Sitter geometry. We introduce new variables to express the Einstein equations as a dynamical system that depends on the equation of st
Externí odkaz:
http://arxiv.org/abs/2205.08125
Autor:
Cotsakis, Spiros, Klaoudatou, Ifigeneia, Kolionis, Georgios, Miritzis, John, Trachilis, Dimitrios
We discuss qualitative features of the conformal relation between certain classes of gravity theories and general relativity, common to different themes such as $f(R)$, Brans-Dicke-type, and string theories. We focus primarily on the frame relations
Externí odkaz:
http://arxiv.org/abs/2202.06536
Publikováno v:
International Journal of Modern Physics A Vol. 34 (2019) 1950092
We consider theories of gravity that include many coupled scalar fields with arbitrary couplings, in the geometric framework of wave maps. We examine the possibility of obtaining acceptable cosmological solutions without the inclusion of a potential
Externí odkaz:
http://arxiv.org/abs/1905.11049
Publikováno v:
Eur. Phys. J. Plus (2020) 135:367
We study the late time evolution of negatively curved Friedmann--Le\-ma\^{\i}tre--Robert\-son--Walker (FLRW) models with a perfect fluid matter source and a scalar field nonminimally coupled to matter. Since, under mild assumptions on the potential $
Externí odkaz:
http://arxiv.org/abs/1905.01742
Completing a previous analysis started in [1], we study flat Friedmann--Lema\^{\i}tre--Robertson--Walker (FLRW) models with a perfect fluid matter source and a scalar field nonminimally coupled to matter, self--interacting with a potential that may a
Externí odkaz:
http://arxiv.org/abs/1506.08162
Autor:
Cotsakis, Spiros1,2 (AUTHOR) skot@aegean.gr, Miritzis, John3 (AUTHOR)
Publikováno v:
Mathematics (2227-7390). Feb2023, Vol. 11 Issue 3, p633. 6p.
We study Friedmann--Robertson--Walker models with a perfect fluid matter source and a scalar field nonminimally coupled to matter. We prove that a general class of bounded from above potentials which fall to minus infinity as the field goes to minus
Externí odkaz:
http://arxiv.org/abs/1411.0218