Fixed point annihilation for a spin in a fluctuating field

Article

关键词: PHASE-TRANSITIONS;    QUANTUM IMPURITY;    POTTS-MODEL;    RENORMALIZATION;    DIMENSIONS;    DYNAMICS;    STATE;   

DOI  :  10.1103/PhysRevB.106.L081109

来源: SCIE

【 摘 要 】

A quantum spin impurity coupled to a gapless free field (the Bose-Kondo model) can be represented as a (0+1)-dimensional field theory with long-range-in-time interactions that decay as |t - t'|(-(2-8)). This theory is a simpler analog of nonlinear sigma models with topological Wess-Zumino-Witten terms in higher dimensions. In this Letter we show that the renormalization group (RG) flows for the impurity problem exhibit an annihilation between two nontrivial RG fixed points at a critical value delta(c) of the interaction exponent. The calculation is controlled at large spin S. This clarifies the phase diagram of the Bose-Kondo model and shows that it serves as a toy model for phenomena involving fixed point annihilation and quasiuniversalityin higher dimensions.

【 授权许可】

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