Essential spectra of quasi-parabolic composition operators on hardy spaces of analytic functions
Gül, Uğur (2010) Essential spectra of quasi-parabolic composition operators on hardy spaces of analytic functions. (Accepted/In Press)
Official URL: http://dx.doi.org/10.1016/j.jmaa.2010.11.055
In this work we study the essential spectra of composition operators on Hardy spaces of analytic functions which might be termed as “quasi-parabolic.” This is the class of composition operators on H2 with symbols whose conjugate with the Cayley transform on the upper half-plane are of the form φ(z)=z+ψ(z), where and (ψ(z))>>0. We especially examine the case where ψ is discontinuous at infinity. A new method is devised to show that this type of composition operator fall in a C*-algebra of Toeplitz operators and Fourier multipliers. This method enables us to provide new examples of essentially normal composition operators and to calculate their essential spectra.
Available Versions of this Item
Repository Staff Only: item control page