Search results for "Holomorphic function"
showing 10 items of 94 documents
An asymptotic holomorphic boundary problem on arbitrary open sets in Riemann surfaces
2020
Abstract We show that if U is an arbitrary open subset of a Riemann surface and φ an arbitrary continuous function on the boundary ∂ U , then there exists a holomorphic function φ ˜ on U such that, for every p ∈ ∂ U , φ ˜ ( x ) → φ ( p ) , as x → p outside a set of density 0 at p relative to U . These “solutions to a boundary problem” are not unique. In fact they can be required to have interpolating properties and also to assume all complex values near every boundary point. Our result is new even for the unit disc.
anQCD: Fortran programs for couplings at complex momenta in various analytic QCD models
2015
We provide three Fortran programs which evaluate the QCD analytic (holomorphic) couplings $\mathcal{A}_{\nu}(Q^2)$ for complex or real squared momenta $Q^2$. These couplings are holomorphic analogs of the powers $a(Q^2)^{\nu}$ of the underlying perturbative QCD (pQCD) coupling $a(Q^2) \equiv \alpha_s(Q^2)/\pi$, in three analytic QCD models (anQCD): Fractional Analytic Perturbation Theory (FAPT), Two-delta analytic QCD (2$\delta$anQCD), and Massive Perturbation Theory (MPT). The index $\nu$ can be noninteger. The provided programs do basically the same job as the Mathematica package anQCD.m in Mathematica published by us previously, Ref.[1], but are now written in Fortran.
Homomorphisms on spaces of weakly continuous holomorphic functions
1999
Let X be a Banach space and let $X^{\ast }$ be its topological dual space. We study the algebra ${\cal H}_{w^\ast}(X^{\ast})$ of entire functions on $X^{\ast }$ that are weak-star continuous on bounded sets. We prove that every m-homogeneous polynomial of finite type P on $X^*$ that is weak-star continuous on bounded sets can be written in the form $P=\textstyle\sum\limits _{j=1}^q x_{1j}\cdots x_{mj}$ where $x_{ij} \in X$ , for all i,j. As an application, we characterize convolution homomorphisms on ${\cal H}_{w^\ast}(X^{\ast})$ and on the space ${\cal H}_{wu}(X)$ of entire functions on X which are weakly uniformly continuous on bounded subsets of X, assuming that X * has the approximation…
Two Minicourses on Analytic Microlocal Analysis
2018
These notes correspond roughly to the two minicourses prepared by the authors for the workshop on Analytic Microlocal Analysis, held at Northwestern University in May 2013. The first part of the text gives an elementary introduction to some global aspects of the theory of metaplectic FBI transforms, while the second part develops the general techniques of the analytic microlocal analysis in exponentially weighted spaces of holomorphic functions.
On the structure of the similarity orbits of Jordan operators as analytic homogeneous manifolds
1989
For Jordan elementsJ in a topological algebraB with unite, an open groupB−1 of invertible elements and continuous inversion we consider the similarity orbitsS G (J)={gJg−1:g∈G} (G the groupB−1⋂{e+c:c∈I},I⊂B a bilateral continuous embedded topological ideal). We construct rational local cross sections to the conjugation mapping\(\pi ^J G \to S_G \left( J \right)\left( {\pi ^J \left( g \right) = gJg^{ - 1} } \right)\) and give to the orbitS G (J) the local structure of a rational manifold. Of particular interest is the caseB=L(H) (bounded linear operators on a separable Hilbert spaceH),I=B, for which we obtain the following: 1. If for a Hilbert space operator there exist norm continuous local…
Envelopes of open sets and extending holomorphic functions on dual Banach spaces
2010
We investigate certain envelopes of open sets in dual Banach spaces which are related to extending holomorphic functions. We give a variety of examples of absolutely convex sets showing that the extension is in many cases not possible. We also establish connections to the study of iterated weak* sequential closures of convex sets in the dual of separable spaces.
Boundary correspondence of Nevanlinna counting functions for self-maps of the unit disc
2003
Let ϕ \phi be a holomorphic self-map of the unit disc D \mathbb {D} . For every α ∈ ∂ D \alpha \in \partial \mathbb {D} , there is a measure τ α \tau _\alpha on ∂ D \partial \mathbb {D} (sometimes called Aleksandrov measure) defined by the Poisson representation Re ( α + ϕ ( z ) ) / ( α − ϕ ( z ) ) = ∫ P ( z , ζ ) d τ α ( ζ ) \operatorname {Re}(\alpha +\phi (z))/(\alpha -\phi (z)) = \int P(z,\zeta ) \,d\tau _\alpha (\zeta ) . Its singular part σ α \sigma _\alpha measures in a natural way the “affinity” of ϕ \phi for the boundary value α \alpha . The affinity for values w w inside D \mathbb {D} is provided by the Nevanlinna counting function N ( w ) N(w) of ϕ \phi . We introduce a natural …
HOLOMORPHIC SUPERPOSITION OPERATORS BETWEEN BANACH FUNCTION SPACES
2013
AbstractWe prove that for a large class of Banach function spaces continuity and holomorphy of superposition operators are equivalent and that bounded superposition operators are continuous. We also use techniques from infinite dimensional holomorphy to establish the boundedness of certain superposition operators. Finally, we apply our results to the study of superposition operators on weighted spaces of holomorphic functions and the$F(p, \alpha , \beta )$spaces of Zhao. Some independent properties on these spaces are also obtained.
Homomorphisms between Algebras of Holomorphic Functions
2014
For two complex Banach spaces X and Y, in this paper, we study the generalized spectrum M-b(X,Y) of all nonzero algebra homomorphisms from H-b(X), the algebra of all bounded type entire functions on X into H-b(Y). We endow M-b(X,Y) with a structure of Riemann domain over L(X*,Y*) whenever.. is symmetrically regular. The size of the fibers is also studied. Following the philosophy of ( Aron et al., 1991), this is a step to study the set M-b,M-infinity (X,B-Y) of all nonzero algebra homomorphisms from Hb(b) (X) into H-infinity (B-Y) of bounded holomorphic functions on the open unit ball of Y and M-infinity(B-X,B-Y) of all nonzero algebra homomorphisms from H-infinity(B-X) into H infinity (B-Y…
Hilbert-Schmidt Hankel operators on the Segal-Bargmann space
2004
This paper considers Hankel operators on the Segal-Bargmann space of holomorphic functions onCn\mathbb {C}^nthat are square integrable with respect to the Gaussian measure. It is shown that in the case of a bounded symbolg∈L∞(Cn)g \in L^{\infty }(\mathbb {C}^n)the Hankel operatorHgH_gis of the Hilbert-Schmidt class if and only ifHg¯H_{\bar {g}}is Hilbert-Schmidt. In the case where the symbol is square integrable with respect to the Lebesgue measure it is known that the Hilbert-Schmidt norms of the Hankel operatorsHgH_gandHg¯H_{\bar {g}}coincide. But, in general, if we deal with bounded symbols, only the inequality‖Hg‖HS≤2‖Hg¯‖HS\|H_g\|_{HS}\leq 2\|H_{\bar {g}}\|_{HS}can be proved. The resul…