ForschungKondensierte Materie
Thermal form factor expansions of the dynamical two-point functions of local operators in integrable quantum chains

Thermal form factor expansions of the dynamical two-point functions of local operators in integrable quantum chains

Frank Göhmann (Universität Wuppertal)

Ort: großer Seminarraum 268, Appelstraße 2
Zeit: 14:00 Uhr

Abstract

We have initiated a study of dynamical two-point functions of arbitrary local operators in integrable lattice models by means of thermal form factor series. These are obtained as expansions in a basis of eigenstates of an appropriately defined quantum transfer matrix. The latter is different from the transfer matrix that generates the Hamiltonian. The quantum transfer matrix rather is an abstract object that generates lattice path integral representations of the partition function and of correlation functions of quantum chains. For integrable quantum chains it can be constructed in such a way that its spectrum and eigenstates can be calculated by integrable methods such as the algebraic Bethe Ansatz. After explaining the general formalism, I shall show that thermal form factor series provide explicit representations of dynamical two-point correlation functions of the XXZ quantum spin chain in the thermodynamic limit that are efficient for numerical and asymptotic analysis. Concrete examples of spectral functions and of current-current functions that determine the transport properties of the spin chain wil be considered.