The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Peter K. F. Kuhfittig - One of the best experts on this subject based on the ideXlab platform.
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Stable wormholes on a noncommutative-geometry background admitting a one-Parameter Group of conformal motions
Indian Journal of Physics, 2015Co-Authors: Peter K. F. KuhfittigAbstract:When Morris and Thorne first proposed the possible existence of traversable wormholes, they adopted the following strategy: maintain complete control over the geometry, thereby leaving open the determination of the stress–energy tensor. In this paper we determine this tensor by starting with a noncommutative-geometry background and assuming that the static and spherically symmetric spacetime admits conformal motions. We have shown that the wormhole obtained can be made stable to linearized radial perturbations.
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wormholes with a barotropic equation of state admitting a one Parameter Group of conformal motions
Annals of Physics, 2015Co-Authors: Peter K. F. KuhfittigAbstract:The theoretical construction of a traversable wormhole proposed by Morris and Thorne maintains complete control over the geometry by assigning both the shape and redshift functions, thereby leaving open the determination of the stress–energy tensor. This paper examines the effect of introducing the linear barotropic equation of state pr=ωρ on the theoretical construction. If either the energy density or the closely related shape function is known, then the Einstein field equations do not ordinarily yield a finite redshift function. If, however, the wormhole admits a one-Parameter Group of conformal motions, then both the redshift and shape functions exist provided that −3<ω<−1. In a cosmological setting, the equation of state p=ωρ, ω<−1, is associated with phantom dark energy, which is known to support traversable wormholes. The restriction −3<ω<−1 that arises in the present wormhole setting can be attributed to the assumption of conformal symmetry.
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wormholes with a barotropic equation of state admitting a one Parameter Group of conformal motions
arXiv: General Relativity and Quantum Cosmology, 2015Co-Authors: Peter K. F. KuhfittigAbstract:The theoretical construction of a traversable wormhole proposed by Morris and Thorne maintains complete control over the geometry by assigning both the shape and redshift functions, thereby leaving open the determination of the stress-energy tensor. This paper examines the effect of introducing the linear barotropic equation of state $p_r=\omega\rho$ on the theoretical construction. If either the energy density or the closely related shape function is known, then the Einstein field equations do not ordinarily yield a finite redshift function. If, however, the wormhole admits a one-Parameter Group of conformal motions, then both the redshift and shape functions exist provided that $\omega <-1$. In a cosmological setting, the equation of state $p=\omega\rho$, $\omega <-1$, is associated with phantom dark energy, which is known to support traversable wormholes.
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Wormholes with a barotropic equation of state admitting a one-Parameter Group of conformal motions
Annals of Physics, 2015Co-Authors: Peter K. F. KuhfittigAbstract:The theoretical construction of a traversable wormhole proposed by Morris and Thorne maintains complete control over the geometry by assigning both the shape and redshift functions, thereby leaving open the determination of the stress–energy tensor. This paper examines the effect of introducing the linear barotropic equation of state pr=ωρ on the theoretical construction. If either the energy density or the closely related shape function is known, then the Einstein field equations do not ordinarily yield a finite redshift function. If, however, the wormhole admits a one-Parameter Group of conformal motions, then both the redshift and shape functions exist provided that −3
Eva A. Gallardo-gutiérrez - One of the best experts on this subject based on the ideXlab platform.
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Unitary equivalence of one-Parameter Groups of Toeplitz and composition operators
Journal of Functional Analysis, 2011Co-Authors: Carl C. Cowen, Eva A. Gallardo-gutiérrezAbstract:Abstract The composition operators on H 2 whose symbols are hyperbolic automorphisms of the unit disk fixing ±1 comprise a one-Parameter Group and the analytic Toeplitz operators coming from covering maps of annuli centered at the origin whose radii are reciprocals also form a one-Parameter Group. Using the eigenvectors of the composition operators and of the adjoints of the Toeplitz operators, a direct unitary equivalence is found between the restrictions to z H 2 of the Group of Toeplitz operators and the Group of adjoints of these composition operators. On the other hand, it is shown that there is not a unitary equivalence of the Groups of Toeplitz operators and the adjoints of the composition operators on the whole of H 2 , but there is a similarity between them.
Joachim Toft - One of the best experts on this subject based on the ideXlab platform.
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Liftings for ultra-modulation spaces, and one-Parameter Groups of Gevrey-type pseudo-differential operators
Analysis and Applications, 2019Co-Authors: Ahmed Abdeljawad, Sandro Coriasco, Joachim ToftAbstract:We deduce one-Parameter Group properties for pseudo-differential operators Op(a), where a belongs to the class Λ∗(ω0) of certain Gevrey symbols. We use this to show that there are pseudo-differenti ...
Saroj Kumbhare - One of the best experts on this subject based on the ideXlab platform.
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higher dimensional strange quark matter coupled to the string cloud with electromagnetic field admitting one Parameter Group of conformal motion
Chinese Physics Letters, 2007Co-Authors: Anirudh Pradhan, G S Khadekar, Mukesh Kumar Mishra, Saroj KumbhareAbstract:We solve Einstein's field equations in higher-dimensional spherically symmetric spacetime with strange quark matter attached to the string cloud, assuming one Parameter Group of conformal motions. The solutions match with the higher-dimensional Reissner–Nordstrom metric on the boundary at r = r0. The features of the solutions are also discussed in the framework of higher-dimensional spacetime.
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higher dimensional strange quark matter coupled to the string cloud with electromagnetic field admitting one Parameter Group of conformal motion
arXiv: General Relativity and Quantum Cosmology, 2007Co-Authors: Anirudh Pradhan, G S Khadekar, Mukesh Kumar Mishra, Saroj KumbhareAbstract:This paper has been withdrawn by arXiv administrators because of an inappropriate amount of overlap with hep-th/0505013.
Carl C. Cowen - One of the best experts on this subject based on the ideXlab platform.
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Unitary equivalence of one-Parameter Groups of Toeplitz and composition operators
Journal of Functional Analysis, 2011Co-Authors: Carl C. Cowen, Eva A. Gallardo-gutiérrezAbstract:Abstract The composition operators on H 2 whose symbols are hyperbolic automorphisms of the unit disk fixing ±1 comprise a one-Parameter Group and the analytic Toeplitz operators coming from covering maps of annuli centered at the origin whose radii are reciprocals also form a one-Parameter Group. Using the eigenvectors of the composition operators and of the adjoints of the Toeplitz operators, a direct unitary equivalence is found between the restrictions to z H 2 of the Group of Toeplitz operators and the Group of adjoints of these composition operators. On the other hand, it is shown that there is not a unitary equivalence of the Groups of Toeplitz operators and the adjoints of the composition operators on the whole of H 2 , but there is a similarity between them.