标题： 规范理论描述自旋链和自旋梯 显示英文标题

标题： Gauge Theory Description of Spin Chains and Ladders

摘要： 一个自旋为 S = 1/2 的反铁磁自旋链被映射到无质量的施温格模型，该模型允许无能隙模式。 在自旋梯子系统中，阶梯相互作用破坏了手征不变性。 这些系统通过玻色化得以求解。 如果循环对称梯子系统的腿数为偶数，则所有自旋链的无能隙模式都变为有能隙。 然而，如果腿数为奇数，则其中一个无能隙模式组合仍保持无能隙。 对于两腿系统，我们发现当交错链间的海森堡耦合 J' 与链内海森堡耦合相比很小时，自旋能隙约为 0.36 |J'|。 显示英文摘要

摘要： An S=1/2 anti-ferromagnetic spin chain is mapped to the two-flavor massless Schwinger model, which admits a gapless mode. In a spin ladder system rung interactions break the chiral invariance. These systems are solved by bosonization. If the number of legs in a cyclically symmetric ladder system is even, all of the gapless modes of spin chains become gapful. However, if the number of legs is odd, one combination of the gapless modes remains gapless. For a two-leg system we find that the spin gap is about .36 |J'| when the inter-chain Heisenberg coupling J' is small compared with the intra-chain Heisenberg coupling.