Covariance principle and covariance group in presence of external E.M. Fields

2008 ◽  
pp. 53-60
Author(s):  
N. Giovannini
Keyword(s):  
Covariance Principle ◽  
Covariance Group

Investigation on the Use of a Spacetime Formalism for Modeling and Numerical Simulations of Heat Conduction Phenomena

2020 ◽  
Vol 45 (3) ◽  
pp. 223-246
Author(s):  
Roula Al Nahas ◽  
Alexandre Charles ◽  
Benoît Panicaud ◽  
Emmanuelle Rouhaud ◽  
Israa Choucair ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Heat Equation ◽  
Numerical Simulations ◽  
Numerical Comparison ◽  
Thermal Models ◽  
Frame Indifference ◽  
Thermomechanical Couplings ◽  
Covariance Principle

AbstractThe question of frame-indifference of the thermomechanical models has to be addressed to deal correctly with the behavior of matter undergoing finite transformations. In this work, we propose to test a spacetime formalism to investigate the benefits of the covariance principle for application to covariant modeling and numerical simulations for finite transformations. Several models especially for heat conduction are proposed following this framework and next compared to existing models. This article also investigates numerical simulations using the heat equation with two different thermal dissipative models for heat conduction, without thermomechanical couplings. The numerical comparison between the spacetime thermal models derived in this work and the corresponding Newtonian thermal models, which adds the time as a discretized variable, is also performed through an example to investigate their advantages and drawbacks.

COVARIANCE GROUP C*-ALGEBRAS AND GALOIS CORRESPONDENCE

1991 ◽  
Vol 02 (06) ◽  
pp. 673-699 ◽  
Author(s):  
PALLE E. T. JORGENSEN ◽  
XIU-CHI QUAN
Keyword(s):  
Main Body ◽  
Normal Subgroups ◽  
C Algebra ◽  
Group System ◽  
C Algebras ◽  
Galois Correspondence ◽  
Covariance Group ◽  
The Given ◽  
The Way

The main purpose of this paper is to establish a Galois correspondence for a given covariant group system, its associated C*-algebra and Hopf C*-algebra. On the way to this, we first study covariance group C*-algebras and their representations, and prove a result which is simpler but yet very similar to the C*-algebra case in the main body of the paper. We then show that there is a Galois correspondence between the lattice of normal subgroups of the given covariant group system and a corresponding lattice of certain invariant *-subalgebras of the covariant group C*-algebra; in particular, there is a natural Galois correspondence for the group C*-algebra. We further study this Galois correspondence for the Hopf C*-algebras associated with covariant group systems.

scholarly journals Massless QFT and the Newton-Wigner Operator

2019 ◽  
Vol 6 (1) ◽  
pp. 43-63
Author(s):  
A. Much
Keyword(s):  
Scalar Field ◽  
Conformal Group ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Wigner Operator ◽  
Spatial Coordinate ◽  
Covariance Group

In this work, the second-quantized version of the spatial-coordinate operator, known as the Newton-Wigner-Pryce operator, is explicitly given w.r.t. the massless scalar field. Moreover, transformations of the conformal group are calculated on eigenfunctions of this operator in order to investigate the covariance group w.r.t. probability amplitudes of localizing particles.

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