arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0901.4152math.PRmath-phmath.MP
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树的临界Ising模型的混合时间在高度上是多项式的

Mixing time of critical Ising model on trees is polynomial in the height

Jian Ding, Eyal Lubetzky, Yuval Peres

摘要:

在格点上伊辛模型的热浴Glauber动力学中,物理学家认为连续时间链的谱隙表现出以下行为。对于某些临界逆温$β_c$,逆能隙对于$β< β_c$是有界的,对于$β= β_c$是多项式的,对于$β> β_c$是指数的.除临界状态外,这一点已在$\Z^2$中得到证明。到目前为止,唯一的基本几何中的临界行为已被证实是完全图。最近,伊辛模型的动力学在一个规则的树,也被称为贝特格,已被深入研究。建立了$β< β_c$的反能隙是有界的,$β> β_c$的反能隙是指数的事实,其中$β_c$是临界自旋玻璃参数,树高$h$起着表面积的作用.在这项工作中,我们完成了$b$ -ary树的伊辛模型的逆间隙的图片,通过显示它确实是多项式在$h$在临界。我们的多项式界的次数不依赖于$b$,而且,这个结果在任何边界条件下都成立。我们还获得了类似的边界的混合时间的链。此外,我们还研究了$β> β_c$的近临界行为,证明了它的反能隙和混合时间都是$\exp[Θ((β-β_c) h)]$。

英文摘要:

In the heat-bath Glauber dynamics for the Ising model on the lattice, physicists believe that the spectral gap of the continuous-time chain exhibits the following behavior. For some critical inverse-temperature $β_c$, the inverse-gap is bounded for $β< β_c$, polynomial in the surface area for $β= β_c$ and exponential in it for $β> β_c$. This has been proved for $\Z^2$ except at criticality. So far, the only underlying geometry where the critical behavior has been confirmed is the complete graph. Recently, the dynamics for the Ising model on a regular tree, also known as the Bethe lattice, has been intensively studied. The facts that the inverse-gap is bounded for $β< β_c$ and exponential for $β> β_c$ were established, where $β_c$ is the critical spin-glass parameter, and the tree-height $h$ plays the role of the surface area. In this work, we complete the picture for the inverse-gap of the Ising model on the $b$-ary tree, by showing that it is indeed polynomial in $h$ at criticality. The degree of our polynomial bound does not depend on $b$, and furthermore, this result holds under any boundary condition. We also obtain analogous bounds for the mixing-time of the chain. In addition, we study the near critical behavior, and show that for $β> β_c$, the inverse-gap and mixing-time are both $\exp[Θ((β-β_c) h)]$.

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