Zobrazeno 1 - 10
of 940
pro vyhledávání: '"Kamenshchik, A."'
Autor:
Kamenshchik, Alexander
Publikováno v:
General Relativity and Gravitation, 56, 133 (2024)
We discuss the problem of singularity crossing in isotropic and anisotropic universes. We study at which conditions singularities can disappear in quantum cosmology and how quantum particles behave in the vicinity of singularities. Some attempts to d
Externí odkaz:
http://arxiv.org/abs/2411.01917
We explore two-point and four-point correlation functions of a massive scalar field on the flat de Sitter background in the long-wavelength approximation. By employing the Yang-Feldman-type equation, we compute the two-point correlation function up t
Externí odkaz:
http://arxiv.org/abs/2410.16226
We study cosmological models based on the interior of the revisited Schwarzschild black hole recently reported in [Phys.~Rev.~D{\bf 109} (2024) 104032]. We find that these solutions describe a non-trivial Kantowski-Sachs universe, for which we provid
Externí odkaz:
http://arxiv.org/abs/2407.14130
Autor:
Kamenshchik, Alexander Y., Pozdeeva, Ekaterina O., Tribolet, Augustin, Tronconi, Alessandro, Venturi, Giovanni, Vernov, Sergey Yu.
The superpotential method is a reconstruction technique which has proven useful to build exact cosmological solutions. We here employ the superpotential method in order to reconstruct the features necessary for the inflaton potential to drive inflati
Externí odkaz:
http://arxiv.org/abs/2406.19762
Publikováno v:
Published in Universe, 10 (3) 137 (2024), Special Issue "The Friedmann Cosmology: A Century Later"
We apply a very simple procedure to construct non-singular cosmological models for flat Friedmann universes filled with minimally coupled scalar fields or by tachyon Born-Infeld-type fields. Remarkably, for the minimally coupled scalar field and the
Externí odkaz:
http://arxiv.org/abs/2403.08400
Autor:
Casadio, Roberto, Chataignier, Leonardo, Kamenshchik, Alexander Yu., Pedro, Francisco G., Tronconi, Alessandro, Venturi, Giovanni
Publikováno v:
Annals of Physics 470, 169783 (2024)
We make a conceptual overview of a particular approach to the initial-value problem in canonical gauge theories. We stress how the first-class phase-space constraints may be relaxed if we interpret them as fixing the values of new degrees of freedom.
Externí odkaz:
http://arxiv.org/abs/2402.12437
We present a simple analytical model for studying the collapse of an ultracompact stellar object (regular black hole mimicker with infinite redshift surface) to form a (integrable) black hole, in the framework of General Relativity. Both initial and
Externí odkaz:
http://arxiv.org/abs/2401.03980
Autor:
Dimakis, Nikolaos, Duffy, Kevin, Giacomini, Alex, Kamenshchik, Alexander Yu., Leon, Genly, Paliathanasis, Andronikos
We investigate the impact of conformal transformations on the physical properties of solution trajectories in nonmetricity gravity. Specifically, we explore the phase-space and reconstruct the cosmological history of a spatially flat Friedmann-Lema\^
Externí odkaz:
http://arxiv.org/abs/2312.11208
Publikováno v:
Phys. Rev. D 109 (2024) 2, 025005
We make an attempt to describe Carroll particles with a non-vanishing value of energy (i.e. the Carroll particles which always stay in rest) in the framework of two time physics, developed in the series of papers by I. Bars and his co-authors. In the
Externí odkaz:
http://arxiv.org/abs/2310.19050
Publikováno v:
Physical Review D 108, 084059 (2023)
We study the effects of a spatially homogenous magnetic field in Bianchi-I cosmological models. The cases of a pure magnetic field and two models with additional dust and a massless scalar field (stiff matter) are also considered. At the beginning of
Externí odkaz:
http://arxiv.org/abs/2307.12830