CRITICAL EXPONENTS OF MIXED QUANTUM SPIN CHAIN

Jill C. Bonner, Gerhard H. Muller

Marcel Kossow, Peter Schupp, Stefan Kettemann

Marcel Kossow, Peter Schupp, Stefan Kettemann

The Heisenberg spin 1/2 chain is revisited in the perturbative RG approach with special focus on the transition of the critical exponents. We give a compact review that first order RG in the couplings is sufficient to derive the exact transition from ν = 1 to ν = 2/3, if the boson radius obtained in the bosonization procedure is replaced by the exact radius obtained in the Bethe approach. We explain the fact, that from the bosonization procedure alone, the critical exponent can not be derived correctly in the isotropic limit Jz → J. We further state that this fact is important if we consider to bosonize the antiferromagnetic super spin chain for the quantum Hall effect.

Satoshi Takada

Joachim Stolze, Taras Verkholyak, Oleg Derzhko +1 more

Holger Frahm, V. E. Korepin

Exact Bethe Ansatz results on the spectrum of large but finite Hubbard chains in conjunction with methods from conformal quantum field theory can be used to obtain exact results for the asymptotic behaviour of correlation functions. We review this method and discuss some interesting consequences of the results.