Bounds on the mass gap of the ferromagnetic XXZ chain
نویسنده
چکیده
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 ∆ → ∞. Near the isotropic point, ∆ = 1, the estimates are good enough to determine the critical behaviour of the mass gap unambiguously. The derivation does not rely on exact solutions.
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تاریخ انتشار 1995