scholarly journals The space–time torsion in the context of the exact Foldy–Wouthuysen transformation for a Dirac fermion

2016 ◽  
Vol 31 (13) ◽  
pp. 1650075 ◽  
Author(s):  
Bruno Gonçalves ◽  
Baltazar J. Ribeiro ◽  
Dante D. Pereira ◽  
Mário M. Dias
Keyword(s):  
Function Space ◽  
Experimental Analysis ◽  
Bound State ◽  
Space Time ◽  
Dirac Fermion ◽  
Dirac Field ◽  
Torsion Field

In this paper, we focus our attention in the inconsistency that appears when the semi-exact Foldy–Wouthuysen transformation for the Dirac field interacting with space–time torsion field is performed. In order to solve this problem, we present a new involution operator that makes possible to perform the exact transformation when torsion field is present. Such operator has a structure, well known in the literature, composed of the product of an operator that acts in the matrices space and another one that acts in the function space. We also present the bound state of this theory and discuss the possible experimental analysis.

Gauge-invariant formulation of axion-electrodynamics

2021 ◽  
Author(s):  
Stanley A. Bruce
Keyword(s):  
Dirac Fermion ◽  
Dirac Field ◽  
Gauge Invariant ◽  
Fermion Fields ◽  
Simple Generalization ◽  
Invariant Formulation ◽  
Em Field

In this paper, we propose a simple generalization of axion-electrodynamics (AED) for the general case in which Dirac fermion fields and scalar/pseudoscalar axion-like fields are present in the local [Formula: see text]([Formula: see text])[Formula: see text] gauge-invariant Lagrangian of the system. Our primary goal (which is not explored here) is to understand and predict novel phenomena that have no counterpart in standard (pseudoscalar) AED. With this end in view, we discuss on very general grounds, possible processes in which a Dirac field is coupled to axionic fields via the electromagnetic (EM) field.

scholarly journals SPIN GAUGE THEORY OF GRAVITY IN CLIFFORD SPACE: A REALIZATION OF KALUZA–KLEIN THEORY IN FOUR-DIMENSIONAL SPACE–TIME

2006 ◽  
Vol 21 (28n29) ◽  
pp. 5905-5956 ◽  
Author(s):  
MATEJ PAVŠIČ
Keyword(s):  
Dimensional Space ◽  
Space Time ◽  
Dirac Field ◽  
Spin Connection ◽  
Yang Mills ◽  
Object A ◽  
Klein Theory ◽  
Dimensional Space Time ◽  
The Right ◽  
Kaluza Klein

A theory in which four-dimensional space–time is generalized to a larger space, namely a 16-dimensional Clifford space (C-space) is investigated. Curved Clifford space can provide a realization of Kaluza–Klein. A covariant Dirac equation in curved C-space is explored. The generalized Dirac field is assumed to be a polyvector-valued object (a Clifford number) which can be written as a superposition of four independent spinors, each spanning a different left ideal of Clifford algebra. The general transformations of a polyvector can act from the left and/or from the right, and form a large gauge group which may contain the group U (1) × SU (2) × SU (3) of the standard model. The generalized spin connection in C-space has the properties of Yang–Mills gauge fields. It contains the ordinary spin connection related to gravity (with torsion), and extra parts describing additional interactions, including those described by the antisymmetric Kalb–Ramond fields.

scholarly journals DUALITIES, COMPOSITENESS AND SPACE–TIME STRUCTURE OF 4D EXTREME STRINGY BLACK HOLES

1999 ◽  
Vol 14 (07) ◽  
pp. 1015-1034 ◽  
Author(s):  
MARIANO CADONI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Bound States ◽  
Bound State ◽  
Space Time ◽  
Naked Singularities ◽  
Heterotic String Theory ◽  
Space Time Structure ◽  
Black Hole Solutions

We study the BPS black hole solutions of the (truncated) action for heterotic string theory compactified on a six-torus. The O (3,Z) duality symmetry of the theory, together with the bound state interpretation of extreme black holes, is used to generate the whole spectrum of the solutions. The corresponding space–time structures, written in terms of the string metric, are analyzed in detail. In particular, we show that only the elementary solutions present naked singularities. The bound states have either null singularities (electric solutions) or are regular (magnetic or dyonic solutions) with near-horizon geometries given by the product of two 2d spaces of constant curvature. The behavior of some of these solutions as supersymmetric attractors is discussed. We also show that our approach is very useful to understand some of the puzzling features of charged black hole solutions in string theory.

scholarly journals Design and experimental analysis of nonreciprocal wave propagation in a space-time modulated beam

2020 ◽  
Author(s):  
Emanuele Riva ◽  
Davide E. Quadrelli ◽  
Jacopo Marconi ◽  
Gabriele Cazzulani ◽  
Francesco Braghin
Keyword(s):  
Wave Propagation ◽  
Experimental Analysis ◽  
Space Time

scholarly journals Solutions of the Schrödinger equation for pseudo-Coulomb potential plus a new improved ring-shaped potential in the cosmic string space–time

2016 ◽  
Vol 94 (5) ◽  
pp. 517-521 ◽  
Author(s):  
Akpan N. Ikot ◽  
Tamunoimi M. Abbey ◽  
Ephraim O. Chukwuocha ◽  
Michael C. Onyeaju
Keyword(s):  
Schrödinger Equation ◽  
Coulomb Potential ◽  
Cosmic String ◽  
Schrodinger Equation ◽  
State Energy ◽  
Bound State ◽  
Space Time ◽  
Minkowski Space Time ◽  
Uvarov Method ◽  
Good Agreement

In this paper, we obtain the bound state energy eigenvalues and the corresponding eigenfunctions of the Schrödinger equation for the pseudo-Coulomb potential plus a new improved ring-shaped potential within the framework of cosmic string space–time using the generalized parametric Nikiforov–Uvarov method. Our results are in good agreement with other works in the cosmic string space–time and reduced to those in the Minkowski space–time when α = 1.

scholarly journals CASIMIR EFFECT FOR THE MASSLESS DIRAC FIELD IN TWO-DIMENSIONAL REISSNER–NORDSTRÖM SPACE–TIME

2006 ◽  
Vol 15 (09) ◽  
pp. 1473-1486 ◽  
Author(s):  
XIN-QIN GAO ◽  
JIAN-YANG ZHU
Keyword(s):  
Black Hole ◽  
Stress Tensor ◽  
Casimir Effect ◽  
Vacuum Expectation ◽  
Space Time ◽  
Dirac Field ◽  
Two Dimensional ◽  
Parallel Plates ◽  
Expectation Values ◽  
Particle Current

In this paper, the two-dimensional Reissner–Nordström black hole is considered as a system of the Casimir type. In this background, the Casimir effect for the massless Dirac field is discussed. The massless Dirac field is confined between two "parallel plates" separated by a distance L and there is no particle current drilling through the boundaries. The vacuum expectation values of the stress tensor of the massless Dirac field at infinity are calculated separately in the Boulware state, the Hartle–Hawking state and the Unruh state.

Study of the Dirac oscillator in the presence of vector and scalar potentials in the cosmic string space-time

2020 ◽  
Vol 35 (21) ◽  
pp. 2050179
Author(s):  
Hao Chen ◽  
Zheng-Wen Long ◽  
Yi Yang ◽  
Chao-Yun Long
Keyword(s):  
Cosmic String ◽  
Topological Defect ◽  
Energy Levels ◽  
Bound State ◽  
Space Time ◽  
Dirac Oscillator ◽  
Ansatz Method ◽  
Cornell Potential ◽  
Scalar Potentials ◽  
Potential Parameters

In this paper, we use the functional Bethe ansatz method to solve the radial problem of the Dirac oscillator in cosmic string space-time, and its general solution under the Killingbeck potential plus isotonic oscillator potential in the limit of the spin and the pseudo-spin symmetries are further presented. Corresponding to the expressions of energies and wave function of bound state and first excited state are given. Furthermore, some particular cases including the Cornell potential, the Kratzer potential, the Killingbeck potential and the isotonic oscillator potentials are also addressed. It shows that the energy levels of the systems depend explicitly on the potential parameters [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and the angular deficit parameter [Formula: see text] which characterize topological defect.

A new length scale for quantum gravity: A resolution of the black hole information loss paradox

2017 ◽  
Vol 26 (12) ◽  
pp. 1743015 ◽  
Author(s):  
Tejinder P. Singh
Keyword(s):  
Black Hole ◽  
Information Loss ◽  
Einstein Equations ◽  
Dirac Field ◽  
Length Scale ◽  
Compton Wavelength ◽  
Information Loss Paradox ◽  
Torsion Field ◽  
Black Hole Information ◽  
Schwarzschild Radius

We show why and how Compton wavelength and Schwarzschild radius should be combined into one single new length scale, which we call the Compton–Schwarzschild length. Doing so offers a resolution of the black hole information loss paradox, and suggests Planck mass remnant black holes as candidates for dark matter. It also compels us to introduce torsion, and identify the Dirac field with a complex torsion field. Dirac equation and Einstein equations, are shown to be mutually dual limiting cases of an underlying gravitation theory which involves the Compton–Schwarzschild length scale, and includes a complex torsion field.

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