标题： 威尔逊环与断弦态的重叠 显示英文标题

标题： Overlap of the Wilson loop with the broken-string state

摘要： 在大多数与物质耦合的规范理论的数值实验中，仅测量威尔逊环时未能观察到弦断裂效应。 我们表明，在相当温和的假设下，威尔逊环算符与断裂弦态的重叠遵循一个自然的上界，这意味着弦断裂的信号通常太弱，无法被传统的更新算法检测到。 为了减少三维 Z_2 规范希格斯模型中威尔逊环的方差，我们使用了一种基于卢舍尔-魏斯方法的新算法，结合非局部聚类算法，可以跟踪矩形威尔逊环的衰减至大约 10^{-24}的值。 通过这种方式，发现了弦断裂的清晰信号。 显示英文摘要

摘要： Numerical experiments on most gauge theories coupled with matter failed to observe string-breaking effects while measuring Wilson loops only. We show that, under rather mild assumptions, the overlap of the Wilson loop operator with the broken-string state obeys a natural upper bound implying that the signal of string-breaking is in general too weak to be detected by the conventional updating algorithms. In order to reduce the variance of the Wilson loops in 3-D Z_2 gauge Higgs model we use a new algorithm based on the L\"uscher-Weisz method combined with a non-local cluster algorithm which allows to follow the decay of rectangular Wilson loops up to values of the order of 10^{-24}. In this way a sharp signal of string breaking is found.