Bounds on the mass gap of the ferromagnetic XXZ chain

Abstract

We prove rigorous lower and upper bounds for the mass gap of the ferromagnetic spin 1/2 XXZ chain. The two bounds coincide asymptotically in the Ising limit $\Delta \to \infty$. Near the isotropic point, $\Delta =1$, the estimates are good enough to determine the critical behaviour of the mass gap unambiguously. The derivation does not rely on exact solutions.

arXiv comment18 pages, LaTeX, 1 figure as uuencoded compressed Postscript file

Cited by in corpus (1)

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