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Fluid space–times and conharmonic symmetries

Journal of Mathematical Physics, 1998
The conharmonic curvature tensor is considered as an invariant of the conharmonic transformation defined by Ishii and the necessary and sufficient conditions for the conharmonic curvature tensor in a perfect fluid space–time to be divergence free has been obtained. Conharmonic motion, conharmonic collineation, and conharmonic curvature collineation are
Abdussattar, Dwivedi, Babita
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Concerning Space-Time and Symmetry Groups

Physical Review, 1964
Several theorems are proved which exhibit the impossibility of constructing nontrivial products of the Lorentz group with internal symmetry groups for some physically interesting examples. It is also shown that if the Lorentz group is replaced by the Galilei group, qualitatively different results are obtained; a "linear" breakdown of internal symmetry ...
Mayer, M. E.   +4 more
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Symmetries of space-time and geodesic symmetries

Journal of Mathematical Physics, 1990
It is shown how to construct symmetries of the geodesic equation starting from space-time symmetries. The constants of motion associated with space-time symmetries are recovered and a few new ones are found using non-Noetherian conservation theorems. Explicit examples are presented.
Del-Castillo-Negrete, Diego   +1 more
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Embedded Space-Time and Particle Symmetries

Reviews of Modern Physics, 1965
The bootstrap yields the strong-interactions symmetry provided the hadron currents participating in nonstrong interactions are first fed into it; the alternative course, in which the bootstrap is required to generate the entire symmetry uniquely, with no a priori information from the nonstrong interactions, seems to lie beyond the present techniques ...
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Dynamical symmetry breaking and space-time topology

Physical Review D, 1987
Vacuum polarization and spontaneous symmetry breaking in a two-dimensional massless fermion field theory with quartic interactions (the Gross-Neveu model) are studied in a cylindrical (${R}^{1}$\ifmmode\times\else\texttimes\fi{}${S}^{1}$) space-time topology. In the case of untwisted fermion fields the symmetry-breaking behavior is similar to the model
, Kim, , Namgung, , Soh, , Yee
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Internal-Symmetry Groups and Curved Space-Time

Physical Review, 1965
Some theorems are proved which exhibit the impossibility of constructing nontrivial products of the 3+2 de Sitter group with internal-symmetry groups (under physically reasonable assumptions). It is shown that either mass degeneracy, $[{E}_{\ensuremath{\alpha}},{P}_{\ensuremath{\mu}}]=0$, or simultaneous measurement of internal quantum numbers and ...
Acharya, R., Narayanaswamy, P.
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Symmetries of Space-Time

2019
Abstract This chapter discusses preliminary concepts needed for the book: relativity and relativistic kinematics, natural units, elements of group theory, discrete symmetries of space ...
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Macroscopic symmetry in space-time

Reports on Progress in Physics, 1963
Magnetic and non-magnetic crystallographic point groups may be distinguished by the different relations in which they stand to the time-inversion or anti-identity operator R. The 32 point groups of classical crystallography G may be used to generate both magnetic and non-magnetic groups.
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Invariant Approach to a Space-Time Symmetry

Journal of Mathematical Physics, 1971
A study is made of Killing vector fields in vacuum Einstein spaces with a restriction primarily to those fields whose associated bivector is nonnull. However, a well-known theorem of Robinson is modified slightly to show that if such a space admits a null bivector associated with a Killing vector, the space must be algebraically special.
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SPACE–TIME DISCRETE ℚ-SYMMETRIES IMPLEMENTED AS INTERNAL SYMMETRIES

International Journal of Geometric Methods in Modern Physics, 2006
We classify the irreducible quaternionic representations of the extensions of internal symmetry groups by the group of space–time discrete symmetries. We obtain the possible forms of time reversal violating Hamiltonians in the case that the generalized parity operator is of geometrical type.
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