论文标题
非扰动异常阈值
Nonperturbative Anomalous Thresholds
论文作者
论文摘要
Feynman图（尤其是三角形图）涉及重量足够的颗粒的分支在物理板上包含分支 - 异常阈值 - 与正常的阈值和绑定状态杆不同，它与任何渐近$ n $ n $粒子状态都不相对应。 ``谁命令命令？''我们表明，异常的阈值是由于已建立的S-矩阵原则和两个合理的假设而出现的：低于物理区域的单位性和大规模的分析性。我们在$ d = 2 $ d = 4 $ d = 4 $ d = 4 $ d = 4 $ d = 4 $ d = 4 $ d = 4 $ d = 4 $ d = 4 $ d = 4现象学应用。
Feynman diagrams (notably the triangle diagram) involving heavy enough particles contain branch cuts on the physical sheet - anomalous thresholds - which, unlike normal thresholds and bound-state poles, do not correspond to any asymptotic $n$-particle state. ``Who ordered that?" We show that anomalous thresholds arise as a consequence of established S-matrix principles and two reasonable assumptions: unitarity below the physical region and analyticity in the mass. We find explicit nonperturbative formulas for the discontinuity across the anomalous threshold in $d=2$, and in $d = 4$, ready to be used in dispersion relations for bootstrap and phenomenological applications.
