标题： 有效弦在QED$_3$ 显示英文标题

标题： Effective Strings in QED$_3$

摘要： 有效弦理论描述了在诸如杨-米尔斯理论这样的理论中长束缚弦的物理，其中质量间隙$M_{gap}^2$与弦张力$T$处在同一数量级。 在$2+1$维度中，有一类束缚理论，包括由Polyakov首次分析的带有质量的QED$_3$，对于这些理论，$M_{gap}^2\ll T$。 这些理论在能量量级为$M_{gap}$的低能下是弱耦合的，可以进行微扰分析。 在本文中，我们分析了这些理论中的弦的物理特性，重点关注QED$_3$，在约$M_{gap}$的能量下（但仍远低于$\sqrt{T}$）。 我们认为，在弦不是指数级长的情况下，这些理论中弦的宽度应为约$1/M_{gap}$，与它的长度无关。 我们还计算了在微扰理论的领先阶次下，圆环上束缚弦的基态能量，以及Nambu-Goldstone玻色子在弦世界面上的散射。 显示英文摘要

摘要： Effective string theory describes the physics of long confining strings in theories, like Yang-Mills theory, where the mass gap $M_{gap}^2$ is of the same order as the string tension $T$. In $2+1$ dimensions, there is a class of confining theories, including massive QED$_3$ as first analyzed by Polyakov, for which $M_{gap}^2\ll T$. These theories are weakly coupled at low energies of order $M_{gap}$, and may be analyzed perturbatively. In this paper, we analyze the physics of strings in such theories, focusing on QED$_3$, at energies of order $M_{gap}$ (but still well below $\sqrt{T}$). We argue that the width of the string in these theories should be of order $1/M_{gap}$ independently of its length, as long as the string is not exponentially long. We also compute at leading order in perturbation theory the ground state energy of a confining string on a circle, and the scattering of Nambu-Goldstone bosons on the string worldsheet.