Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 65: Low-Dimensional Systems: 1D – Theory

TT 65.6: Talk

Wednesday, March 18, 2015, 16:30–16:45, H 0104

Exact calculation of thermal correlation functions of the antiferromagnetic Heisenberg chain at large distances — •Frank Göhmann and Maxime Dugave — Bergische Universität Wuppertal

Thermal correlation functions of integrable models in the thermodynamic limit can be expanded in a basis of eigenstates of the corresponding quantum transfer matrix. This provides an asymptotic expansion in which every term is determined by a correlation length and by an amplitude. We have derived exact formulae for the amplitudes for the longitudinal and transverse correlation functions of the anisotropic Heisenberg chain in the spin liquid regime as functions of temperature and magnetic field. In the zero temperature limit infinitely many correlation lengths diverge, while the amplitudes decay algebraically with temperature, with the same critical exponents that determine the spatial decay of the ground state correlation functions. We have summed up these infinitely many terms exactly and, as a result, have obtained efficient expressions for the amplitudes of the critical correlation functions, generalizing well-known formulae of Lukyanov to finite magnetic fields.