BERTHA: Implementation of a four-component Dirac–Kohn–Sham relativistic framework

2020 ◽  
Vol 152 (16) ◽  
pp. 164118 ◽  
Author(s):  
Leonardo Belpassi ◽  
Matteo De Santis ◽  
Harry M. Quiney ◽  
Francesco Tarantelli ◽  
Loriano Storchi
Keyword(s):  
Relativistic Framework

scholarly journals The Celestial Reference System in Relativistic Framework

1990 ◽  
Vol 141 ◽  
pp. 99-110
Author(s):  
Han Chun-Hao ◽  
Huang Tian-Yi ◽  
Xu Bang-Xin
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Reference System ◽  
Light Deflection ◽  
Coordinate Systems ◽  
Definition Of ◽  
Celestial Sphere ◽  
Celestial Reference System ◽  
Relativistic Framework

The concept of reference system, reference frame, coordinate system and celestial sphere in a relativistic framework are given. The problems on the choice of celestial coordinate systems and the definition of the light deflection are discussed. Our suggestions are listed in Sec. 5.

Hermann Weyl's Analysis of the “Problem of Space” and the Origin of Gauge Structures

2004 ◽  
Vol 17 (1-2) ◽  
pp. 165-197 ◽  
Author(s):  
Erhard Scholz
Keyword(s):  
General Relativity ◽  
Dirac Equation ◽  
A Priori ◽  
Group Extension ◽  
Central Idea ◽  
German Word ◽  
General Relativistic ◽  
Empirical Turn ◽  
Relativistic Framework ◽  
Internal Symmetries

Hermann Weyl (1885–1955) was one of the early contributors to the mathematics of general relativity. This article argues that in 1929, for the formulation of a general relativistic framework of the Dirac equation, he both abolished and preserved in modified form the conceptual perspective that he had developed earlier in his “analysis of the problem of space.” The ideas of infinitesimal congruence from the early 1920s were aufgehoben (in all senses of the German word) in the general relativistic framework for the Dirac equation. He preserved the central idea of gauge as a “purely infinitesimal” aspect of (internal) symmetries in a group extension schema. With respect to methodology, however, Weyl gave up his earlier preferences for relatively a-priori arguments and tried to incorporate as much empiricism as he could. This signified a clearly expressed empirical turn for him. Moreover, in this step he emphasized that the mathematical objects used for the representation of matter structures stood at the center of the construction, rather than interaction fields which, in the early 1920s, he had considered as more or less derivable from geometrico-philosophical considerations.

Pseudospin symmetry as an accidental symmetry in the relativistic framework

2008 ◽  
Vol 37 (2) ◽  
Author(s):  
S. Marcos ◽  
M. López-Quelle ◽  
R. Niembro ◽  
L. N. Savushkin
Keyword(s):  
Pseudospin Symmetry ◽  
Relativistic Framework ◽  
Accidental Symmetry

Asymmetric Neutrino Reaction from Magnetized Proto-Neutron Stars in fully Relativistic Framework including Hyperons

2010 ◽  
Author(s):  
Tomoyuki Maruyama ◽  
Nobutoshi Yasutake ◽  
Toshitaka Kajino ◽  
Myung-Ki Cheoun ◽  
Chung-Yeol Ryu ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Neutrino Reaction ◽  
Relativistic Framework

scholarly journals Astronomical Units and Constants in a Relativistic Framework

1995 ◽  
Vol 10 ◽  
pp. 201-201
Author(s):  
N. Capitaine ◽  
B. Guinot
Keyword(s):  
General Relativity ◽  
Minimum Degree ◽  
Degree Of Approximation ◽  
Theoretical Background ◽  
Point Of View ◽  
Astronomical Unit ◽  
Dynamical Astronomy ◽  
Unit Of Length ◽  
Relativistic Framework ◽  
Astronomical Constants

In 1991, IAU Resolution A4 introduced General Relativity as the theoretical background for defining celestial space-time reference sytems. It is now essential that units and constants used in dynamical astronomy be defined in the same framework, at least in a manner which is compatible with the minimum degree of approximation of the metrics given in Resolution A4.This resolution states that astronomical constants and quantities should be expressed in SI units, but does not consider the use of astronomical units. We should first evaluate the usefulness of maintaining the system of astronomical units. If this system is kept, it must be defined in the spirit of Resolution A4. According to Huang T.-Y., Han C.-H., Yi Z.-H., Xu B.-X. (What is the astronomical unit of length?, to be published in Asttron. Astrophys.), the astronomical units for time and length are units for proper quantities and are therefore proper quantities. We fully concur with this point of view. Astronomical units are used to establish the system of graduation of coordinates which appear in ephemerides: the graduation units are not, properly speaking astronomical units. Astronomical constants, expressed in SI or astronomical units, are also proper quantities.

scholarly journals Relativistic Models for a GAIA-Like Astrometry Mission

2000 ◽  
Vol 180 ◽  
pp. 314-319 ◽  
Author(s):  
F. de Felice ◽  
A. Vecchiato ◽  
B. Bucciarelli ◽  
M.G. Lattanzi ◽  
M. Crosta
Keyword(s):  
Reference Frame ◽  
Fundamental Physics ◽  
Accurate Knowledge ◽  
Adopted Model ◽  
Relativistic Approach ◽  
General Relativistic ◽  
Relativistic Models ◽  
Relativistic Parameter ◽  
Relativistic Framework ◽  
Better Than

A non-perturbative general relativistic approach to global astrometry was developed by de Felice et al. (1998) to handle satellite astrometry data in a genuine relativistic framework. In this contribution, the framework above has been further exploited to account for stellar motions and parallax. Because of the relevance that accurate knowledge (to 10−5 or better) of the relativistic parameter γ has to fundamental physics, a Parametrized Post-Newtonian (PPN) model has also been implemented, which allows the direct estimation of γ along with the astrometric parameters. These models have been tested on end-to-end simulations of the mission GAIA. The results show that, within the limitation of the simulation and the assumptions of the adopted model, measurements accurate to 100 μarcsec of large arcs among stars repeated over a few years can be modelled to establish a dense reference frame with a precision of a few tens of μarcseconds. Moreover, our experiments indicate that γ can be estimated to better than 10−6.

scholarly journals The Relativistic Boltzmann Equation and Two Times

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 804
Author(s):  
L. P. Horwitz
Keyword(s):  
Boltzmann Equation ◽  
Monotonic Function ◽  
Relativistic Boltzmann Equation ◽  
Pair Annihilation ◽  
System Of Particles ◽  
Normal Particle ◽  
Invariant Parameter ◽  
Relativistic Framework

We discuss a covariant relativistic Boltzmann equation which describes the evolution of a system of particles in spacetime evolving with a universal invariant parameter τ . The observed time t of Einstein and Maxwell, in the presence of interaction, is not necessarily a monotonic function of τ . If t ( τ ) increases with τ , the worldline may be associated with a normal particle, but if it is decreasing in τ , it is observed in the laboratory as an antiparticle. This paper discusses the implications for entropy evolution in this relativistic framework. It is shown that if an ensemble of particles and antiparticles, converge in a region of pair annihilation, the entropy of the antiparticle beam may decreaase in time.

Relation between wave speeds in the crust of dense magnetic stars

1978 ◽  
Vol 364 (1719) ◽  
pp. 537-552 ◽  
Keyword(s):  
Magnetic Field ◽  
Initial Pressure ◽  
The Body ◽  
Perfect Conductor ◽  
Initial State ◽  
Wave Speeds ◽  
Magnetic Stars ◽  
Arbitrary Strength ◽  
The Magnetic Field ◽  
Relativistic Framework

By studying, within the relativistic framework, the propagation of so-called infinitesimal discontinuities throughout a magnetized elastic perfect conductor in an initial state of high hydrostatic pressure p 0 and in the presence of a magnetic field of arbitrary strength, it is proven that there hold universal relations (i. e., that do not depend on the exact equation of state of the body) between the speeds U f and U s of so-called fast and slow magnetoelastic modes. These results, which should hold true in the crust of dense magnetic stars, have the following form. If A 0 is the relativistic Alfvén number of the initial state and a 0 is the sound speed of a fictitious relativistic perfect fluid whose law of compression would yield the initial pressure p o , then (with nondimensional speeds) U 2 / f = 4/3[ U 2 s (1+ A 2 0 ]+( a 2 0 -4/3 A 2 0 ) for a propagation along the magnetic field and U 2 f (1+ A 2 0 )=4/3 U 2 s +( a 2 0 + A 2 0 ) for a propagation in a direction orthogonal to the magnetic field. These results generalize previous results obtained in relativistic elasticity by Carter and Maugin.

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