scholarly journals Integrals of subharmonic functions and their differences with weight over small sets on a ray

2020 ◽  
Vol 54 (2) ◽  
pp. 162-171
Author(s):  
B.N. Khabibullin
Keyword(s):  
Characteristic Function ◽  
Lebesgue Measure ◽  
Real Axis ◽  
Complex Plane ◽  
Measurable Subset ◽  
Positive Part ◽  
Subharmonic Functions ◽  
The Real ◽  
The Difference

Let $E$ be a measurable subset in a segment $[0,r]$ in the positive part of the real axis in the complex plane, and $U=u-v$ be the difference of subharmonic functions $u\not\equiv -\infty$ and $v\not\equiv -\infty$ on the complex plane. An integral of the maximum on circles centered at zero of $U^+:=\sup\{0,U\} $ or $|u|$ over $E$ with a function-multiplier $g\in L^p(E) $ in the integrand is estimated, respectively, in terms of the characteristic function $T_U$ of $U$ or the maximum of $u$ on circles centered at zero, and also in terms of the linear Lebesgue measure of $E$ and the $ L^p$-norm of $g$. Our main theorem develops the proof of one of the classical theorems of Rolf Nevanlinna in the case $E=[0,R]$, given in the classical monograph by Anatoly A. Goldberg and Iossif V. Ostrovsky, and also generalizes analogs of the Edrei\,--\,Fuchs Lemma on small arcs for small intervals from the works of A.\,F.~Grishin, M.\,L.~Sodin, T.\,I.~Malyutina. Our estimates are uniform in the sense that the constants in these estimates do not depend on $U$ or $u$, provided that $U$ has an integral normalization near zero or $u(0)\geq 0$, respectively.

Successive coefficients of close-to-convex functions

2020 ◽  
Vol 32 (5) ◽  
pp. 1131-1141 ◽  
Author(s):  
Paweł Zaprawa
Keyword(s):  
Real Axis ◽  
Convex Functions ◽  
Positive Direction ◽  
The Real ◽  
Coefficient Problems ◽  
The Difference

AbstractIn this paper we discuss coefficient problems for functions in the class {{\mathcal{C}}_{0}(k)}. This family is a subset of {{\mathcal{C}}}, the class of close-to-convex functions, consisting of functions which are convex in the positive direction of the real axis. Our main aim is to find some bounds of the difference of successive coefficients depending on the fixed second coefficient. Under this assumption we also estimate {|a_{n+1}|-|a_{n}|} and {|a_{n}|}. Moreover, it is proved that {\operatorname{Re}\{a_{n}\}\geq 0} for all {f\in{\mathcal{C}}_{0}(k)}.

scholarly journals Pseudo-hermitian random matrix theory: a review

2021 ◽  
Vol 2038 (1) ◽  
pp. 012009
Author(s):  
Joshua Feinberg ◽  
Roman Riser
Keyword(s):  
Real Axis ◽  
Complex Plane ◽  
Random Matrix Theory ◽  
Random Matrix ◽  
Matrix Theory ◽  
Complex Conjugate ◽  
Indefinite Metric ◽  
The Real ◽  
New Type ◽  
Diagrammatic Method

Abstract We review our recent results on pseudo-hermitian random matrix theory which were hitherto presented in various conferences and talks. (Detailed accounts of our work will appear soon in separate publications.) Following an introduction of this new type of random matrices, we focus on two specific models of matrices which are pseudo-hermitian with respect to a given indefinite metric B. Eigenvalues of pseudo-hermitian matrices are either real, or come in complex-conjugate pairs. The diagrammatic method is applied to deriving explicit analytical expressions for the density of eigenvalues in the complex plane and on the real axis, in the large-N, planar limit. In one of the models we discuss, the metric B depends on a certain real parameter t. As t varies, the model exhibits various ‘phase transitions’ associated with eigenvalues flowing from the complex plane onto the real axis, causing disjoint eigenvalue support intervals to merge. Our analytical results agree well with presented numerical simulations.

scholarly journals Global parameterization of $$\pi \pi $$ scattering up to 2 $${\mathrm {\,GeV}}$$

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
J. R. Pelaez ◽  
A. Rodas ◽  
J. Ruiz de Elvira
Keyword(s):  
Experimental Data ◽  
Partial Wave ◽  
Real Axis ◽  
Complex Plane ◽  
Dispersion Relations ◽  
The Real ◽  
Partial Waves

AbstractWe provide global parameterizations of $$\pi \pi \rightarrow \pi \pi $$ππ→ππ scattering S0 and P partial waves up to roughly 2 GeV for phenomenological use. These parameterizations describe the output and uncertainties of previous partial-wave dispersive analyses of $$\pi \pi \rightarrow \pi \pi $$ππ→ππ, both in the real axis up to 1.12 $${\mathrm {\,GeV}}$$GeV and in the complex plane within their applicability region, while also fulfilling forward dispersion relations up to 1.43 $${\mathrm {\,GeV}}$$GeV. Above that energy we just describe the available experimental data. Moreover, the analytic continuations of these global parameterizations also describe accurately the dispersive determinations of the $$\sigma /f_0(500)$$σ/f0(500), $$f_0(980)$$f0(980) and $$\rho (770)$$ρ(770) pole parameters.

scholarly journals Plummeting and blinking eigenvalues of the Robin Laplacian in a cuspidal domain

2019 ◽  
Vol 150 (6) ◽  
pp. 2871-2893 ◽  
Author(s):  
Sergei A. Nazarov ◽  
Nicolas Popoff ◽  
Jari Taskinen
Keyword(s):  
Dimension Reduction ◽  
Discrete Spectrum ◽  
Spectral Theory ◽  
Real Axis ◽  
Complex Plane ◽  
Lipschitz Domain ◽  
High Rate ◽  
The Real ◽  
Robin Laplacian ◽  
Asymptotic Forms

We consider the Robin Laplacian in the domains Ω and Ωε, ε > 0, with sharp and blunted cusps, respectively. Assuming that the Robin coefficient a is large enough, the spectrum of the problem in Ω is known to be residual and to cover the whole complex plane, but on the contrary, the spectrum in the Lipschitz domain Ωε is discrete. However, our results reveal the strange behaviour of the discrete spectrum as the blunting parameter ε tends to 0: we construct asymptotic forms of the eigenvalues and detect families of ‘hardly movable’ and ‘plummeting’ ones. The first type of the eigenvalues do not leave a small neighbourhood of a point for any small ε > 0 while the second ones move at a high rate O(| ln ε|) downwards along the real axis ℝ to −∞. At the same time, any point λ ∈ ℝ is a ‘blinking eigenvalue’, i.e., it belongs to the spectrum of the problem in Ωε almost periodically in the | ln ε|-scale. Besides standard spectral theory, we use the techniques of dimension reduction and self-adjoint extensions to obtain these results.

On certain expansions of the solutions of the general Lamé equation

1942 ◽  
Vol 38 (4) ◽  
pp. 364-367 ◽  
Author(s):  
A. Erdélyi
Keyword(s):  
Real Axis ◽  
Complex Plane ◽  
Recurrence Relations ◽  
Characteristic Exponent ◽  
Periodic Functions ◽  
The Real ◽  
Lamé Equation ◽  
Arbitrary Complex ◽  
Principal Value ◽  
Image Position

1. In this paper I shall deal with the solutions of the Lamé equationwhen n and h are arbitrary complex or real parameters and k is any number in the complex plane cut along the real axis from 1 to ∞ and from −1 to −∞. Since the coefficients of (1) are periodic functions of am(x, k), we conclude ](5), § 19·4] that there is a solution of (1), y0(x), which has a trigonometric expansion of the formwhere θ is a certain constant, the characteristic exponent, which depends on h, k and n. Unless θ is an integer, y0(x) and y0(−x) are two distinct solutions of the Lamé equation.It is easy to obtain the system of recurrence relationsfor the coefficients cr. θ is determined, mod 1, by the condition that this system of recurrence relations should have a solution {cr} for whichk′ being the principal value of (1−k2)½

scholarly journals The spectra of compact operators in Hilbert spaces

1965 ◽  
Vol 7 (1) ◽  
pp. 34-38
Author(s):  
T. T. West
Keyword(s):  
Hilbert Space ◽  
Unit Circle ◽  
Real Axis ◽  
Complex Plane ◽  
Hilbert Spaces ◽  
Compact Operators ◽  
Conformal Mappings ◽  
The Real ◽  
Finite Set

In [2] a condition, originally due to Olagunju, was given for the spectra of certain compact operators to be on the real axis of the complex plane. Here, by using conformal mappings, this result is extended to more general curves. The problem divides naturally into two cases depending on whether or not the curve under consideration passes through the origin. Discussion is confined to the prototype curves C0 and C1. The case of C0, the unit circle of centre the origin, is considered in § 3; this problem is a simple one as the spectrum is a finite set. In § 4 results are given for C1 the unit circle of centre the point 1, and some results on ideals of compact operators, given in § 2, are needed. No attempt has been made to state results in complete generality (see [2]); this paper is kept within the framework of Hilbert space, and particularly simple conditions may be given if the operators are normal.

FRACTAL IMAGES OF GENERALIZED JULIA SETS

Fractals ◽  
1996 ◽  
Vol 04 (04) ◽  
pp. 533-541 ◽  
Author(s):  
KIM-KHOON ONG ◽  
AICHYUN SHIAH ◽  
ZDZISLAW E. MUSIELAK
Keyword(s):  
Real Axis ◽  
Complex Plane ◽  
Julia Sets ◽  
Real Numbers ◽  
Positive Real ◽  
The Real ◽  
Fractal Images ◽  
Zero Values ◽  
Principal Value ◽  
Iteration Function

The iteration function [Formula: see text], where both α and β are positive real numbers, is used to generate families of the generalized Julia sets, [Formula: see text]. The calculations are restricted to the principal value of zα + iβ and the obtained results demonstrate that classical Julia sets, [Formula: see text] are significantly deformed when non-zero values of β are considered. As a result of this deformation, the area of stable regions in the complex plane changes and a process of splitting and shifting takes place along the real axis. It is shown that this process is responsible for the formation of new fractal images of generalized Julia sets.

A Geometric Representation

1918 ◽  
Vol 10 (4) ◽  
pp. 205-210
Author(s):  
E. D. Roe
Keyword(s):  
Real Axis ◽  
Complex Plane ◽  
Plane Curve ◽  
Real Plane ◽  
Geometric Representation ◽  
Independent Equation ◽  
The Real ◽  
Real Locus ◽  
Axis Parallel ◽  
Real Curves

In order to visualize the complex values of y, when such exist, of a plane curve y=f(x), or a surface y=f(x, z), and also for the purpose of representing some real curves in space by a single independent equation in x and y, I adjoin an ordinary complex plane, perpendicular to the x axis of the real xy plane, with its real axis parallel to the y axis, in fact always in the real plane and with its origin in the axis of x, so that the complex plane slides along always perpendicular to the x axis, OX, and at distance x from O the origin of the xy plane, as x changes. By this representation the equation of every curve or surface has an actual and uninterrupted locus from − ∞ to + ∞, including the usual real locus of y = f (x) or y = f (x, z), and some real curves in space can be represented by a single independent equation between two variables x and y.

scholarly journals Extending Quantum Probability from Real Axis to Complex Plane

2020 ◽  
Author(s):  
Ciann-Dong Yang ◽  
Shiang-Yi Han
Keyword(s):  
Real Axis ◽  
Complex Plane ◽  
Planck Equation ◽  
Bohmian Mechanics ◽  
Quantum Probability ◽  
Classical Probability ◽  
The Real ◽  
Guidance Law ◽  
Definition Of ◽  
Open Question

Probability is an open question in the ontological interpretation of quantum mechanics. It has been discussed in some trajectory interpretations such as Bohmian mechanics and stochastic mechanics. New questions arise when the domain of probability extends to the complex space, including the generation of complex trajectories, the definition of the complex probability, the relation of the complex probability to the real quantum probability, and so on. The complex treatment proposed here applies the optimal quantum guidance law to derive the stochastic differential (SD) equation governing the particle’s random motions in the complex plane. The ensemble of the complex quantum random trajectories (CQRTs) solved from the complex SD equation is used to construct the probability distribution ρc(t,x,y) of the particle’s position over the complex plane z=x+iy. The correctness of the obtained complex probability is confirmed by the solution of the complex Fokker-Planck equation. The significant contribution of the complex probability is that it can be used to reconstruct both quantum probability and classical probability, and to clarify their relationship. Although quantum probability and classical probability are both defined on the real axis, they are obtained by projecting complex probability onto the real axis in different ways. This difference explains why the quantum probability cannot exactly converge to the classical probability when the quantum number is large.

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