radial variable
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2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Yue-Zhou Li ◽  
H. Lü ◽  
Liang Ma

Abstract It is known that the (a, c) central charges in four-dimensional CFTs are linear combinations of the three independent OPE coefficients of the stress-tensor three-point function. In this paper, we adopt the holographic approach using AdS gravity as an effect field theory and consider higher-order corrections up to and including the cubic Riemann tensor invariants. We derive the holographic central charges and OPE coefficients and show that they are invariant under the metric field redefinition. We further discover a hidden relation among the OPE coefficients that two of them can be expressed in terms of the third using differential operators, which are the unit radial vector and the Laplacian of a four-dimensional hyperbolic space whose radial variable is an appropriate length parameter that is invariant under the field redefinition. Furthermore, we prove that the consequential relation c = 1/3ℓeff∂a/∂ℓeff and its higher-dimensional generalization are valid for massless AdS gravity constructed from the most general Riemann tensor invariants.


Author(s):  
A. Alexandrov ◽  
O. Stashko ◽  
V. Zhdanov

Stationary spherically symmetric space-time in the quasi-global coordinates is considered in presence of scalar field (SF) minimally coupled to gravity, with a monomial potential V(ϕ)=ϕn, n>4. We prove convergence of an iterative method to solve the joint system of Einstein – SF equations at sufficiently large distances from the center. The result can be used for a numerical solution for the metric and SF by means of backwards integration from large values of the radial variable to smaller ones.


2018 ◽  
Vol 63 (9) ◽  
pp. 777
Author(s):  
M. V. Vavrukh ◽  
D. V. Dzikovskyi ◽  
S. V. Smerechynskyi

Using the equation of state of the electron-nuclear model at high densities and the mechanical equilibrium equation, we have investigated the influence of interparticle interactions and the axial rotation on the macroscopic characteristics (mass, surface shape) of massive degenerate dwarfs. We propose a method of solving the equilibrium equation in the case of rotation that uses the basis of universal functions of the radial variable. The conditions, under which the axial rotation can compensate for a weight loss of the mass due to the Coulomb interactions, have been established. The maximal value of the relativistic parameter, at which the stability is disturbed, is determined within the general theory of relativity (GTR).


2018 ◽  
Vol 25 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Alexey N. Karapetyants ◽  
Stefan G. Samko

Abstract Following the ideas of our previous research, in this paper we continue the study of new Bergman-type spaces on the unit disc with mixed norm in terms of Fourier coefficients. Here we deal with the case where the sequence of norms of Fourier coefficients in the Orlicz–Morrey space in radial variable belongs to {l^{q}} . We study the boundedness of the Bergman projection and provide a description of functions in these spaces via the behavior of their Taylor coefficients.


2018 ◽  
Vol 15 (07) ◽  
pp. 1850108 ◽  
Author(s):  
S. V. Bolokhov ◽  
V. D. Ivashchuk

Generalized Melvin solutions for rank-[Formula: see text] Lie algebras [Formula: see text], [Formula: see text] and [Formula: see text] are considered. Any solution contains metric, three Abelian 2-forms and three scalar fields. It is governed by three moduli functions [Formula: see text] ([Formula: see text] and [Formula: see text] is a radial variable), obeying three differential equations with certain boundary conditions imposed. These functions are polynomials with powers [Formula: see text] for Lie algebras [Formula: see text], [Formula: see text], [Formula: see text], respectively. The solutions depend upon integration constants [Formula: see text]. The power-law asymptotic relations for polynomials at large [Formula: see text] are governed by integer-valued [Formula: see text] matrix [Formula: see text], which coincides with twice the inverse Cartan matrix [Formula: see text] for Lie algebras [Formula: see text] and [Formula: see text], while in the [Formula: see text]-case [Formula: see text], where [Formula: see text] is the identity matrix and [Formula: see text] is a permutation matrix, corresponding to a generator of the [Formula: see text]-group of symmetry of the Dynkin diagram. The duality identities for polynomials and asymptotic relations for solutions at large distances are obtained. Two-form flux integrals over a two-dimensional disc of radius [Formula: see text] and corresponding Wilson loop factors over a circle of radius [Formula: see text] are presented.


2018 ◽  
Vol 8 (1) ◽  
pp. 9-15
Author(s):  
D. Dzikovskyi ◽  
M. Vavrukh ◽  
S. Smerechynskyi

Using the equation of state of electron-nuclear model at high densities and the mechanical equilibrium equation we have investigated the influence of interparticle interactions and axial rotation on the macroscopic characteristics of massive white dwarfs. The method of solving the equilibrium equation in the case of rotation, using the basis of universal functions of the radial variable has been proposed. The conditions in which the axial rotation can compensate for weight loss of mass due to the interparticle Coulomb interactions have been established.


2018 ◽  
Vol 168 ◽  
pp. 01010 ◽  
Author(s):  
Jeong-Hyuck Park

Dictated by Symmetry Principle, string theory predicts not General Relativity but its own gravity which assumes the entire closed string massless sector to be geometric and thus gravitational. In terms of R/(MG), i.e. the dimensionless radial variable normalized by mass, Stringy Gravity agrees with General Relativity toward infinity, but modifies it at short distance. At far short distance, gravitational force can be even repulsive. These may solve the dark matter and energy problems, as they arise essentially from small R/(MG) observations: long distance divided by much heavier mass. We address the pertinent differential geometry for Stringy Gravity, stringy Equivalence Principle, stringy geodesics and the minimal coupling to the Standard Model. We highlight the notion of ‘doubled-yet-gauged’ coordinate system, in which a gauge orbit corresponds to a single physical point and proper distance is defined between two gauge orbits by a path integral.


2017 ◽  
Vol 4 (8) ◽  
pp. 170484 ◽  
Author(s):  
Siyuan Bao ◽  
Shuodao Wang

A generalized solution procedure is developed for in-plane free vibration of rectangular and annular sectorial plates with general boundary conditions. For the annular sectorial plate, the introduction of a logarithmic radial variable simplifies the basic theory and the expression of the total energy. The coordinates, geometric parameters and potential energy for the two different shapes are organized in a unified framework such that a generalized solving procedure becomes feasible. By using the improved Fourier–Ritz approach, the admissible functions are formulated in trigonometric form, which allows the explicit assembly of global mass and stiffness matrices for both rectangular and annular sectorial plates, thereby making the method computationally effective, especially when analysing annular sectorial plates. Moreover, the improved Fourier expansion eliminates the potential discontinuity of the original normal and tangential displacement functions and their derivatives in the entire domain, and accelerates the convergence. The generalized Fourier–Ritz approach for both shapes has the characteristics of generality, accuracy and efficiency. These features are demonstrated via a few numerical examples.


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