The Conformal Group of a Conformally Flat Space Time and Its Twistor Representations

1986 ◽  
pp. 5-19
Author(s):  
Ivan T. Todorov
Keyword(s):  
Flat Space ◽  
Space Time ◽  
Conformal Group ◽  
Conformally Flat

Long-range scalar field in conformally flat space-time

1978 ◽  
Vol 17 (8) ◽  
pp. 631-634 ◽  
Author(s):  
M. M. Som ◽  
N. O. Santos
Keyword(s):  
Scalar Field ◽  
Long Range ◽  
Flat Space ◽  
Space Time ◽  
Conformally Flat

Perfect fluid in a conformally flat space time

1980 ◽  
Vol 13 (1) ◽  
pp. 191-197 ◽  
Author(s):  
M M Som ◽  
N O Santos
Keyword(s):  
Perfect Fluid ◽  
Flat Space ◽  
Space Time ◽  
Conformally Flat

Fluid with heat flux in a conformally flat space-time

1982 ◽  
Vol 25 (10) ◽  
pp. 2518-2520 ◽  
Author(s):  
S. R. Maiti
Keyword(s):  
Heat Flux ◽  
Flat Space ◽  
Space Time ◽  
Conformally Flat

scholarly journals Hypersurfaces in a conformally flat space with curvature collineation

1991 ◽  
Vol 14 (3) ◽  
pp. 595-604
Author(s):  
K. L. Duggal ◽  
R. Sharma
Keyword(s):  
Fundamental Problem ◽  
Energy Condition ◽  
Shape Operator ◽  
Flat Space ◽  
Space Time ◽  
Conformally Flat ◽  
Direct Relation ◽  
Shape Operators

We classify the shape operators of Einstein and pseudo Einstein hypersurfaces in a conformally flat space with a symmetry called curvature collineation. We solve the fundamental problem of finding all possible forms of non-diagonalizable shape operators. A physical example of space-time with matter is presented to show that the energy condition has direct relation with the diagonalizability of shape operator.

scholarly journals Divergence-free quantum electrodynamics in locally conformally flat space–time

2021 ◽  
Vol 36 (13) ◽  
pp. 2150083
Author(s):  
John Mashford
Keyword(s):  
Quantum Electrodynamics ◽  
Fock Space ◽  
Grassmann Algebra ◽  
Flat Space ◽  
Space Time ◽  
Conformally Flat ◽  
Direct Sums ◽  
Spectral Regularization ◽  
Locally Conformally Flat ◽  
Divergence Free

This paper describes an approach to quantum electrodynamics (QED) in curved space–time obtained by considering infinite-dimensional algebra bundles associated to a natural principal bundle [Formula: see text] associated with any locally conformally flat space–time, with typical fibers including the Fock space and a space of fermionic multiparticle states which forms a Grassmann algebra. Both these algebras are direct sums of generalized Hilbert spaces. The requirement of [Formula: see text] covariance associated with the geometry of space–time, where [Formula: see text] is the structure group of [Formula: see text], leads to the consideration of [Formula: see text] intertwining operators between various spaces. Scattering processes are associated with such operators and are encoded in an algebra of kernels. Intertwining kernels can be generated using [Formula: see text] covariant matrix-valued measures. Feynman propagators, fermion loops and the electron self-energy can be given well-defined interpretations as such measures. Divergence-free calculations in QED can be carried out by computing the spectra of these measures and kernels (a process called spectral regularization). As an example of the approach the precise Uehling potential function for the [Formula: see text] atom is calculated without requiring renormalization from which the Uehling contribution to the Lamb shift can be calculated exactly.

Dynamics of spherical collapse in energy–momentum squared gravity

2021 ◽  
Vol 36 (01) ◽  
pp. 2150004
Author(s):  
M. Sharif ◽  
M. Zeeshan Gul
Keyword(s):  
Early Time ◽  
Flat Space ◽  
Big Bang ◽  
Space Time ◽  
Spherically Symmetric ◽  
Conformally Flat ◽  
Source Terms ◽  
Dynamical Equations ◽  
Spherical Collapse ◽  
The Impact

This paper investigates the dynamics of spherical collapse in the framework of energy–momentum squared gravity. This theory overcomes the big-bang singularity and provides viable cosmological consequences in the early time universe. We proceed our work by considering the nonstatic spherically symmetric space–time in the interior and static spherically symmetric metric in the exterior regions of the star. The Darmois junction conditions between interior and exterior geometries are derived. We construct dynamical equations through the Misner–Sharp technique to analyze the impact of matter variables and dark source terms on the collapsing phenomenon. A correlation among dark source terms, Weyl scalar and matter variables is also established. Due to the presence of multivariate function and its derivatives, space–time is no longer considered to be conformally flat. To obtain conformally flat space–time, we have considered a particular model of this gravity which yields conformally flat space–time and homogeneity of the energy density through the entire system. We conclude that positive dark source terms as well as negative pressure gradient provide the anti-gravitational behavior leading to the stability of self-gravitating objects and hence prevent the collapsing process.

Stress tensors and their trace anomalies in conformally flat space-time

1977 ◽  
Vol 16 (6) ◽  
pp. 1712-1716 ◽  
Author(s):  
Lowell S. Brown ◽  
James P. Cassidy
Keyword(s):  
Flat Space ◽  
Space Time ◽  
Conformally Flat ◽  
Stress Tensors
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