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arXiv 2203.02518cond-mat.str-elcond-mat.mes-hallcond-mat.stat-mechquant-ph
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SU(2)对称自旋-玻色子模型:量子临界性、不动点湮灭与对偶性

SU(2)-Symmetric Spin-Boson Model: Quantum Criticality, Fixed-Point Annihilation, and Duality

Manuel Weber, Matthias Vojta

AI总结:

针对SU(2)对称自旋1/2自旋-玻色子模型,通过高精度量子蒙特卡罗模拟与标度分析,给出两个RG不动点在s*=0.6540(2)处湮灭的数值证据,揭示其对偶性并给出强耦合解析预言,为该现象的大规模模拟研究提供可能。

摘要:

两个中间耦合重整化群(RG)不动点的湮灭现象是统计力学到高能物理等诸多领域的研究热点,但此前仅通过微扰技术开展过研究。本文给出了SU(2)对称的自旋1/2自旋-玻色子(或称玻色-近藤)模型的高精度量子蒙特卡罗模拟结果。我们研究了具有幂律浴谱(形式为∝ω^s)的该模型,发现除微扰RG预言的临界相外,还存在稳定的强耦合相。通过细致的标度分析,我们提供了两个RG不动点在s*=0.6540(2)处碰撞并湮灭的直接数值证据,这导致s<s*时临界相消失。特别地,我们揭示了两个不动点之间出人意料的对偶性,对应RGβ函数的反射对称性,我们利用该对偶性给出了强耦合下的解析预言,且与数值结果高度吻合。我们的工作使不动点湮灭现象可通过大规模模拟开展研究,并讨论了该结果对临界磁体中杂质磁矩的影响。

英文摘要:

The annihilation of two intermediate-coupling renormalization-group (RG) fixed points is of interest in diverse fields from statistical mechanics to high-energy physics, but has so far only been studied using perturbative techniques. Here we present high-accuracy quantum Monte Carlo results for the SU(2)-symmetric $S=1/2$ spin-boson (or Bose-Kondo) model. We study the model with a power-law bath spectrum $\propto ω^s$ where, in addition to a critical phase predicted by perturbative RG, a stable strong-coupling phase is present. Using a detailed scaling analysis, we provide direct numerical evidence for the collision and annihilation of two RG fixed points at $s^\ast = 0.6540(2)$, causing the critical phase to disappear for $s<s^\ast$. In particular, we uncover a surprising duality between the two fixed points, corresponding to a reflection symmetry of the RG beta function, which we utilize to make analytical predictions at strong coupling which are in excellent agreement with numerics. Our work makes phenomena of fixed-point annihilation accessible to large-scale simulations, and we comment on the consequences for impurity moments in critical magnets.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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